40 C.F.R. §§ 63.1425–63.1430

6 sections in range

§63.1425. Process vent control requirements.

40 C.F.R. § 63.1425

(a)

Applicability of process vent control requirements. For each process vent at an affected source, the owner or operator shall comply with the provisions of this section. Owners and operators of all affected sources using epoxides in the production of polyether polyols are subject to the requirements of paragraph (b) of this section. Owners and operators subject to paragraph (b) of this section are also subject to paragraph (g) of this section for process vents in ethylene oxide service. Owners or operators are also subject to the requirements of paragraph (c) of this section only if epoxides are used in the production of polyether polyols and nonepoxide organic HAP are used to make or modify the product. Similarly, owners or operators are also subject to the requirements of paragraph (d) of this section only if epoxides are used in the production of polyether polyols and organic HAP are used in catalyst extraction. Owners and operators subject to paragraph (b), (c), (d), or (g) of this section are also subject to paragraph (h) of this section if the owner or operator chooses to designate a process vent as a maintenance vent as specified in paragraph (h) of this section. The owner or operator of an affected source where polyether polyol products are produced using tetrahydrofuran shall comply with paragraph (f) of this section.

(b)

Requirements for epoxide emissions. The owner or operator of an affected source where polyether polyol products are produced using epoxides shall reduce epoxide emissions from process vents from batch unit operations and continuous unit operations within each PMPU in accordance with either paragraph (b)(1) or (2) of this section and if applicable, paragraph (g) of this section.

(1)

For new affected sources, the owner or operator shall comply with paragraph (b)(1)(i), (ii), or (iii) this section. The owner or operator also has the option of complying with a combination of paragraphs (b)(1)(i) and (ii) of this section. If the owner or operator chooses to comply with a combination of paragraphs (b)(1)(i) and (ii) of this section, each process vent not controlled in accordance with paragraph (b)(1)(ii) of this section shall be part of the group of applicable process vents that shall then comply with paragraph (b)(1)(i) of this section.

(i)

Reduce the total epoxide emissions from the group of applicable process vents by an aggregated 99.9 percent;

(ii)

Maintain an outlet concentration of total epoxides or TOC after each combustion, recapture, or recovery device of 20 ppmv or less; or

(iii)

Maintain an emission factor of no greater than 4.43 × 10−3 kilogram epoxide emissions per megagram of product (4.43 × 10−3 pounds epoxide emissions per 1,000 pounds of product) for all process vents in the PMPU.

(2)

For existing affected sources, the owner or operator shall comply with either paragraph (b)(2)(i), (ii), (iii), or (iv) of this section. The owner or operator also has the option of complying with a combination of paragraphs (b)(2)(ii) and (iii) of this section. If the owner or operator chooses to comply with a combination of paragraphs (b)(2)(ii) and (iii) of this section, each process vent that is not controlled in accordance with paragraph (b)(2)(iii) of this section shall be part of the group of applicable process vents that shall then comply with paragraph (b)(2)(ii) of this section. The owner or operator also has the option of complying with a combination of paragraphs (b)(2)(i) and (iii) of this section.

(i)

Reduce the total epoxide emissions from each process vent using a flare;

(ii)

Reduce the total epoxide emissions from the group of applicable process vents by an aggregated 98 percent;

(iii)

Maintain an outlet concentration of total epoxides or TOC after each combustion, recapture or recovery devices of 20 ppmv or less; or

(iv)

Maintain an emission factor of no greater than 1.69 × 10−2 kilogram epoxide emissions per megagram of product (1.69 × 10−2 pounds epoxide emissions per 1,000 pounds of product) for all process vents in the PMPU.

(c)

Requirements for nonepoxide organic HAP emissions from making or modifying the product. The owner or operator of a new or existing source where polyether polyols are produced using epoxides, and where nonepoxide organic HAP are used to make or modify the product, shall comply with this paragraph. For each process vent from a continuous unit operation that is associated with the use of a nonepoxide organic HAP to make or modify the product, the owner or operator shall determine if the process vent is a Group 1 continuous process vent, as defined in § 63.1423. For the combination of process vents from batch unit operations that are associated with the use of a nonepoxide organic HAP to make or modify the product, the owner or operator shall determine if the combination of process vents is a Group 1 combination of batch process vents, as defined in § 63.1423.

(1)

Requirements for Group 1 combinations of batch process vents. For each Group 1 combination of batch process vents, as defined in § 63.1423, the owner or operator shall comply with either paragraph (c)(1)(i) or (ii) of this section.

(i)

Reduce nonepoxide organic HAP emissions using a flare.

(ii)

Reduce nonepoxide organic HAP emissions by 90 percent using a combustion, recovery, or recapture device.

(2)

Requirements for Group 2 combinations of batch process vents. For each Group 2 combination of batch process vents, as defined in § 63.1423, the owner or operator reassess the group status when process changes occur, in accordance with the provisions of § 63.1428(g). No control requirements apply to these process vents.

(3)

Requirements for Group 1 continuous process vents. For each Group 1 continuous process vent, as defined in § 63.1423, the owner or operator shall comply with either paragraph (c)(3)(i) or (ii) of this section.

(i)

Reduce nonepoxide organic HAP emissions using a flare.

(ii)

Reduce nonepoxide organic HAP emissions by 98 percent using a combustion, recovery, or recapture device.

(4)

Requirements for Group 2 continuous process vents. For each Group 2 continuous process vent, as defined in § 63.1423, the owner or operator shall comply with either paragraph (c)(4)(i) or (ii) of this section.

(i)

If the TRE for the process vent is greater than 1.0 but less than 4.0, the owner or operator shall comply with the monitoring provisions in § 63.1429, the recordkeeping provisions in § 63.1430(d), and recalculate the TRE index value when process changes occur, in accordance with the provisions in § 63.1428(h)(2).

(ii)

If the TRE for the process vent is greater than 4.0, the owner or operator shall recalculate the TRE index value when process changes occur, in accordance with the provisions in § 63.1428(h)(2).

(d)

Requirements for nonepoxide organic HAP emissions from catalyst extraction. The owner or operator of a new or existing affected source where polyether polyol products are produced using epoxide compounds shall comply with either paragraph (d)(1) or (2) of this section. A PMPU that does not use any nonepoxide organic HAP in catalyst extraction is exempt from the requirements of this paragraph.

(1)

Reduce emissions of nonepoxide organic HAP from all process vents associated with catalyst extraction using a flare; or

(2)

Reduce emissions of nonepoxide organic HAP from the sum total of all process vents associated with catalyst extraction by an aggregated 90 percent for each PMPU.

(e)

[Reserved]

(f)

Requirements for process vents at PMPUs that produce polyether polyol products using tetrahydrofuran. For each process vent in a PMPU that uses tetrahydrofuran (THF) to produce one or more polyether polyol products that is, or is part of, an affected source, the owner or operator shall comply with the HON process vent requirements in §§ 63.113 through 63.118, except as provided for in paragraphs (f)(1) through (10) of this section, and, beginning March 18, 2026, except as provided for in paragraphs (f)(11) through (15) of this section.

(1)

When December 31, 1992 is referred to in the HON process vent requirements in § 63.113, it shall be replaced with September 4, 1997, for the purposes of this subpart.

(2)

When § 63.151(f), alternative monitoring parameters, and § 63.152(e), submission of an operating permit application, are referred to in §§ 63.114(c) and 63.117(e), § 63.1439(f), alternative monitoring parameters, and § 63.1439(e)(8), submission of an operating permit application, respectively, shall apply for the purposes of this subpart.

(3)

When the Notification of Compliance Status requirements contained in § 63.152(b) are referred to in §§ 63.114, 63.117, and 63.118, the Notification of Compliance Status requirements contained in § 63.1439(e)(5) shall apply for the purposes of this subpart.

(4)

When the Periodic Report requirements contained in § 63.152(c) are referred to in §§ 63.117 and 63.118, the Periodic Report requirements contained in § 63.1439(e)(6) shall apply for the purposes of this subpart.

(5)

When the definition of excursion in § 63.152(c)(2)(ii)(A) is referred to in § 63.118(f)(2), the definition of excursion in § 63.1438(f) shall apply for the purposes of this subpart.

(6)

When § 63.114(e) specifies that an owner or operator shall submit the information required in § 63.152(b) in order to establish the parameter monitoring range, the owner or operator shall comply with the provisions of § 63.1438 for establishing the parameter monitoring level and shall comply with § 63.1439(e)(5)(ii) or § 63.1439(e)(8) for the purposes of reporting information related to the establishment of the parameter monitoring level, for the purposes of this subpart. Further, the term “level” shall apply whenever the term “range” is used in §§ 63.114, 63.117, and 63.118.

(7)

When reports of process changes are required under § 63.118(g), (h), (i), or (j), paragraphs (f)(7)(i) through (iv) of this section shall apply for the purposes of this subpart.

(i)

For the purposes of this subpart, whenever a process change, as defined in § 63.115(e), is made that causes a Group 2 process vent to become a Group 1 process vent, the owner or operator shall submit a report within 180 days after the process change is made or the information regarding the process change is known to the owner or operator. This report may be included in the next Periodic Report. A description of the process change shall be included in this report.

(ii)

Whenever a process change, as defined in § 63.115(e), is made that causes a Group 2 process vent with a TRE greater than 4.0 to become a Group 2 process vent with a TRE less than 4.0, the owner or operator shall submit a report within 180 days after the process change is made or the information regarding the process change is known to the owner or operator, unless the flow rate is less than 0.005 standard cubic meters per minute. This report may be included in the next Periodic Report. A description of the process change shall be included in this report.

(iii)

Whenever a process change, as defined in § 63.115(e), is made that causes a Group 2 process vent with a flow rate less than 0.005 standard cubic meter per minute (scmm) to become a Group 2 process vent with a flow rate of 0.005 scmm or greater and a TRE index value less than or equal to 4.0, the owner or operator shall submit a report within 180 days after the process change is made or the information regarding the process change is known to the owner or operator, unless the organic HAP concentration is less than 50 ppmv. This report may be included in the next Periodic Report. A description of the process change shall be submitted with the report.

(iv)

Whenever a process change, as defined in § 63.115(e), is made that causes a Group 2 process vent with an organic HAP concentration less than 50 parts per million by volume (ppmv) to become a Group 2 process vent with an organic HAP concentration of 50 ppmv or greater and a TRE index value less than or equal to 4.0, the owner or operator shall submit a report within 180 days after the process change is made or the information regarding the process change is known to the owner or operator, unless the flow rate is less than 0.005 standard cubic meters per minute. This report may be included in the next Periodic Report. A description of the process change shall be submitted with this report.

(8)

When § 63.118 refers to § 63.152(f), the recordkeeping requirements in § 63.1439(d) shall apply for the purposes of this subpart.

(9)

When §§ 63.115 and 63.116 refer to Table 2 of 40 CFR part 63, subpart F, the owner or operator shall only consider organic HAP as defined in this subpart.

(10)

When the provisions of § 63.116(c)(3) and (4) specify that Method 18, 40 CFR part 60, appendix A shall be used, Method 18 or Method 25A, 40 CFR part 60, appendix A may be used for the purposes of this subpart. The use of Method 25A, 40 CFR part 60, appendix A shall comply with paragraphs (f)(10)(i) and (ii) of this section.

(i)

The organic HAP used as the calibration gas for Method 25A, 40 CFR part 60, appendix A shall be the single organic HAP representing the largest percent by volume of the emissions.

(ii)

The use of Method 25A, 40 CFR part 60, appendix A is acceptable if the response from the high-level calibration gas is at least 20 times the standard deviation of the response from the zero calibration gas when the instrument is zeroed on the most sensitive scale.

(11)

In §§ 63.116(g) and 63.118(a)(5) and (f)(7) substitute “For each source as defined in § 63.101, beginning no later than the compliance dates specified in § 63.100(k)(10),” with “For each affected source as described in § 63.1420(a), beginning no later than the compliance dates specified in § 63.1422(h),”.

(12)

Substitute “as defined in § 63.101” with “as defined in § 63.1423”.

(13)

Substitute “For each source as defined in § 63.101, on and after July 15, 2027,” with “For each affected source as described in § 63.1420(a), on and after March 18, 2029,”.

(14)

Substitute “§ 63.108” with “§ 63.1436”.

(15)

Section 63.113(k)(4) does not apply.

(g)

Process vents in ethylene oxide service. Beginning no later than the compliance dates specified in § 63.1422(h), if a process vent is in ethylene oxide service then the owner or operator must comply with paragraph (g)(1), (2), or (3) of this section in addition to all other applicable requirements specified in this section.

(1)

Reduce emissions of ethylene oxide by venting emissions through a closed vent system to a flare; or

(2)

Reduce emissions of ethylene oxide by venting emissions through a closed vent system to a control device that reduces ethylene oxide by greater than or equal to 99.9 percent by weight, or to a concentration less than 1 ppmv for each process vent or to less than 100 pounds per year for all combined process vents within the process. If a combustion device is used, the ethylene oxide concentration of 1 ppmv must be corrected to 3 percent oxygen.

(3)

Reduce emissions of ethylene oxide by greater than or equal to 99.9 percent by weight or to less than 100 pounds per year for all combined process vents within the process by using ECO as a control technique or by using a combination of ECO and venting emissions through a closed vent system to a control device.

(h)

Maintenance vents. Beginning no later than the compliance dates specified in § 63.1422(h), an owner or operator may designate a process vent that is subject to the requirements in paragraph (b), (c), or (d) of this section as a maintenance vent if the vent is only used as a result of start-up, shutdown, maintenance, or inspection of equipment where equipment is emptied, depressurized, degassed, or placed into service. The owner or operator must comply with the applicable requirements in paragraphs (h)(1) through (3) of this section for each maintenance vent. Any vent designated as a maintenance vent is only subject to the maintenance vent provisions in this paragraph (h) and the associated recordkeeping and reporting requirements in § 63.1430(a) and (h)(9), respectively. The owner or operator does not need to designate a maintenance vent as a Group 1 or Group 2 process vent (for process vents associated with nonepoxide organic HAP emissions from making or modifying product and process vents associated with affected sources that produce polyether polyols using tetrahydrofuran) nor identify maintenance vents in a Notification of Compliance Status report. Note: process vents subject to the requirements in [paragraph (f) of this section may also designate a process vent as a maintenance vent; and even though those standards are the same as the standards specified in this paragraph (h), those standards are specified in the HON process vent requirements according to paragraph (f) of this section.]

(1)

Prior to venting to the atmosphere, remove process liquids from the equipment as much as practical and depressurize the equipment to either: A flare meeting the requirements of § 63.1436, as applicable, or using any combination of a non-flare combustion, recovery, and/or recapture device meeting the requirements in paragraph (b)(1)(i) or (ii), (b)(2)(ii) or (iii), (c)(1)(ii), (c)(3)(ii), or (d)(2) of this section, until one of the following conditions, as applicable, is met.

(i)

The concentration of the vapor in the equipment served by the maintenance vent is less than 10 percent of its lower explosive limit (LEL) and has an outlet concentration less than or equal to 20 ppmv hydrogen halide and halogen HAP.

(ii)

If there is no ability to measure the concentration of the vapor in the equipment based on the design of the equipment, the pressure in the equipment served by the maintenance vent is reduced to 5 pounds per square inch gauge (psig) or less. Upon opening the maintenance vent, active purging of the equipment cannot be used until the concentration of the vapors in the maintenance vent (or inside the equipment if the maintenance is a hatch or similar type of opening) is less than 10 percent of its LEL.

(iii)

The equipment served by the maintenance vent contains less than 50 pounds of total volatile organic compounds (VOC).

(iv)

If, after applying best practices to isolate and purge equipment served by a maintenance vent, none of the applicable criterion in paragraphs (h)(1)(i) through (iii) of this section can be met prior to installing or removing a blind flange or similar equipment blind, then the pressure in the equipment served by the maintenance vent must be reduced to 2 psig or less before installing or removing the equipment blind. During installation or removal of the equipment blind, active purging of the equipment may be used provided the equipment pressure at the location where purge gas is introduced remains at 2 psig or less.

(2)

Except for maintenance vents complying with paragraph (h)(1)(iii) of this section, the owner or operator must determine the concentration or, if applicable, equipment pressure using process instrumentation or portable measurement devices and follow procedures for calibration and maintenance according to manufacturer's specifications.

(3)

For maintenance vents complying with paragraph (h)(1)(iii) of this section, the owner or operator must determine mass of VOC in the equipment served by the maintenance vent based on the equipment size and contents after considering any contents drained or purged from the equipment. Equipment size may be determined from equipment design specifications. Equipment contents may be determined using process knowledge.

Notes, amendments, and revision history

Amendments

[64 FR 29439, June 1, 1999, as amended at 91 FR 13155, Mar. 18, 2026]

Source

Source: 64 FR 29439, June 1, 1999, unless otherwise noted.

Authority

Authority: 42 U.S.C. 7401 et seq.

Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.

Amendments

[64 FR 29439, June 1, 1999, as amended at 91 FR 13155, Mar. 18, 2026]

§63.1426. Process vent requirements for determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a PMPU.

40 C.F.R. § 63.1426

(a)

Use of a flare.

(1)

Except as specified in paragraph (a)(2) of this section, when a flare is used to comply with § 63.1425(b)(1)(i) (in combination with other control techniques), (b)(2)(i), (c)(1)(i), (c)(3)(i), or (d)(1), the owner or operator shall comply with § 63.1437(c), and is not required to demonstrate the control efficiency for the flare, if the owner or operator chooses to assume a 98 percent control efficiency for that flare, as allowed under paragraph (e)(2)(i) of this section. In order to use only a flare to comply with § 63.1425(b)(1)(i), or to use a flare and apply a control efficiency greater than 98 percent, an owner or operator shall submit a request in accordance with § 63.6(g) in either the Precompliance Report described in § 63.1439(e)(4), or in a supplement to the precompliance report, as described in § 63.1439(e)(4)(vii).

(2)

Beginning no later than the compliance dates specified in § 63.1422(h), paragraph (a)(1) of this section no longer applies and instead the owner or operator shall comply with § 63.1436 when a flare is used to comply with § 63.1425(b)(1)(i) (in combination with other control techniques), (b)(2)(i), (c)(1)(i), (c)(3)(i), or (d)(1). In order to use only a flare to comply with § 63.1425(b)(1)(i) or to use a flare and apply a control efficiency greater than 98 percent, an owner or operator shall submit a request in accordance with § 63.670(r), with exceptions noted in § 63.1436, and receive approval by the Administrator.

(b)

Exceptions to performance tests. An owner or operator is not required to conduct a performance test when a combustion, recovery, or recapture device specified in paragraphs (b)(1) through (6) of this section is used to comply with § 63.1425(b), (c), or (d).

(1)

A boiler or process heater with a design heat input capacity of 44 megawatts or greater.

(2)

A boiler or process heater where the process vent stream is introduced with the primary fuel or is used as the primary fuel.

(3)

A combustion, recovery, or recapture device for which a performance test was conducted within the preceding 5-year period, using the same Methods specified in this section and either no deliberate process changes have been made since the test, or the owner or operator can demonstrate that the results of the performance test, with or without adjustments, reliably demonstrate compliance despite process changes is not required to conduct an initial performance test. Subsequent performance tests shall be conducted according to § 63.1437(a). The operating parameters reported under the previous performance test shall be sufficient to meet the parameter monitoring requirements in this subpart.

(4)

A boiler or process heater burning hazardous waste for which the owner or operator—

(i)

Has been issued a final hazardous waste permit under part 270 of this chapter and complies with the requirements for hazardous waste burned in boilers and industrial furnaces in part 266, subpart H of this chapter;

(ii)

Has certified compliance with the interim status requirements for hazardous waste burned in boilers and industrial furnaces in part 266, subpart H of this chapter;

(iii)

Meets the requirement specified in paragraph (b)(4)(v) of this section, and has submitted a Notification of Compliance under § 63.1207(j) and complies with the requirements of subpart EEE of this part; or

(iv)

Meets the requirement specified in paragraph (b)(4)(v) of this section, complies with subpart EEE of this part, and will submit a Notification of Compliance under § 63.1207(j) by the date the owner or operator would have been required to submit the initial performance test report for this subpart.

(v)

The owner and operator may not waive performance testing pursuant to § 63.1207(d)(4).

(5)

A hazardous waste incinerator for which the owner or operator—

(i)

Has been issued a final permit under part 270 of this chapter and complies with the requirements for incinerators in part 264, subpart O of this chapter;

(ii)

Has certified compliance with the interim status requirements for incinerators in part 265, subpart O of this chapter;

(iii)

Meets the requirement specified in paragraph (b)(5)(v) of this section, and has submitted a Notification of Compliance under § 63.1207(j) and complies with the requirements in subpart EEE of this part; or

(iv)

Meets the requirement specified in paragraph (b)(5)(v) of this section, complies with the requirements in subpart EEE of this part, and will submit a Notification of Compliance under § 63.1207(j) by the date the owner or operator would have been required to submit the initial performance test report for this subpart.

(v)

The owner and operator may not waive performance testing pursuant to § 63.1207(d)(4).

(6)

Except as specified in paragraph (b)(7) of this section, combustion, recovery or recapture device (except for condensers) performance may be determined by using the design evaluation described in paragraph (f) of this section, provided that the combustion, recovery or recapture device receives less than 10 tons per year (9.1 megagrams per year) of uncontrolled organic HAP emissions from one or more PMPUs, determined in accordance with paragraph (d) of this section. If a combustion, recovery or recapture device exempted from testing in accordance with this paragraph receives more than 10 tons per year (9.1 megagrams per year) of uncontrolled organic HAP emissions from one or more PMPUs, the owner or operator shall comply with the performance test requirements in paragraph (c) of this section and before March 18, 2026 shall submit the test report in the next Periodic Report. Beginning March 18, 2026, the test report no longer needs to be submitted with the Periodic Report and only needs to be submitted according to § 63.1439(e)(9).

(7)

Beginning on the compliance dates specified in § 63.1422(h), paragraphs (b)(6) and (f) of this section do not apply. Instead, the owner or operator shall comply with the performance test requirements in paragraph (c) of this section.

(c)

Determination of organic HAP concentration and control efficiency. Except as provided in paragraphs (a) and (b) of this section, an owner or operator using a combustion, recovery, or recapture device to comply with an epoxide or organic HAP percent reduction efficiency requirement in § 63.1425(b)(1)(i), (b)(2)(ii), (c)(1)(ii), (c)(3)(ii), or (d)(2); an epoxide concentration limitation in § 63.1425(b)(1)(ii) or (b)(2)(ii); or an annual epoxide emission limitation in § 63.1425(b)(1)(iii) or (b)(2)(iv), shall conduct a performance test using the applicable procedures in paragraphs (c)(1) through (4) of this section. The organic HAP or epoxide concentration and percent reduction may be measured as total epoxide, total organic HAP, or as TOC minus methane and ethane according to the procedures specified. When conducting testing in accordance with this section, the owner or operator is only required to measure HAP of concern for the specific requirement for which compliance is being determined. For instance, to determine compliance with the epoxide emission requirement of § 63.1425(b), the owner or operator is only required to measure epoxide control efficiency or outlet concentration.

(1)

Sampling site location. The sampling site location shall be determined as specified in paragraphs (c)(1)(i) and (ii) of this section.

(i)

For determination of compliance with a percent reduction of total epoxide requirement in § 63.1425(b)(1)(i), (b)(2)(ii), or a percent reduction of total organic HAP requirement in § 63.1425(c)(1)(ii), (c)(3)(ii), or (d)(2), sampling sites shall be located at the inlet of the combustion, recovery, or recapture device as specified in paragraphs (c)(1)(i)(A), (B), and (C) of this section, and at the outlet of the combustion, recovery, or recapture device.

(A)

For process vents from continuous unit operations, the inlet sampling site shall be determined in accordance with either paragraph (c)(1)(i)(A)(1) or (2) of this section.

(1) To demonstrate compliance with either the provisions for epoxide emissions in § 63.1425(b) or the provisions for nonepoxide organic HAP emissions from catalyst extraction in § 63.1425(d), the inlet sampling site shall be located after the exit from the continuous unit operation but before any recovery devices, or

(2) To demonstrate compliance with the requirements for nonepoxide organic HAP emissions from the use of nonepoxide organic HAP in making or modifying the product in § 63.1425(c), the inlet sampling site shall be located after all control techniques to reduce epoxide emissions and after the final nonepoxide organic HAP recovery device.

(B)

For process vents from batch unit operations, the inlet sampling site shall be determined in accordance with either paragraph (c)(1)(i)(B)(1) or (2) of this section.

(1) To demonstrate compliance with either the provisions for epoxide emissions in § 63.1425(b) or the provisions for nonepoxide organic HAP emissions from catalyst extraction in § 63.1425(d), the inlet sampling site shall be located after the exit from the batch unit operation but before any recovery device.

(2) To demonstrate compliance with the requirements for nonepoxide organic HAP emissions in making or modifying the product in § 63.1425(c), the inlet sampling site shall be located after all control techniques to reduce epoxide emissions but before any nonepoxide organic HAP recovery device.

(C)

If a process vent stream is introduced with the combustion air or as a secondary fuel into a boiler or process heater with a design capacity less than 44 megawatts, selection of the location of the inlet sampling sites shall ensure the measurement of total organic HAP or TOC (minus methane and ethane) concentrations in all process vent streams and primary and secondary fuels introduced into the boiler or process heater.

(ii)

To determine compliance with a parts per million by volume total epoxide or TOC limit in § 63.1425(b)(1)(ii) or (b)(2)(iii), the sampling site shall be located at the outlet of the combustion, recovery, or recapture device.

(2)

Frequency. Performance tests and compliance determinations shall be conducted according to the schedule in § 63.1437(a).

(3)

Testing conditions and calculation of TOC or total organic HAP concentration.

(i)

Testing conditions shall be as specified in paragraphs (c)(3)(i)(A) through (E) of this section, as appropriate.

(A)

Testing of process vents from continuous unit operations shall be conducted at maximum representative operating conditions, as described in § 63.1437(a)(1). Each test shall consist of three 1-hour runs. Gas stream volumetric flow rates shall be measured at approximately equal intervals of about 15 minutes during each 1-hour run. The organic HAP concentration (of the HAP of concern) shall be determined from samples collected in an integrated sample over the duration of each 1-hour test run, or from grab samples collected simultaneously with the flow rate measurements (at approximately equal intervals of about 15 minutes). If an integrated sample is collected for laboratory analysis, the sampling rate shall be adjusted proportionally to reflect variations in flow rate. For gas streams from continuous unit operations, the organic HAP concentration or control efficiency used to determine compliance shall be the average organic HAP concentration or control efficiency of the three test runs.

(B)

Testing of process vents from batch unit operations shall be conducted at absolute worst-case conditions or hypothetical worst-case conditions, as defined in paragraphs (c)(3)(i)(B)(1) through (5) of this section. Worst-case conditions are limited to the maximum production allowed in a state or Federal permit or regulation and the conditions specified in § 63.1437(a)(1). Gas stream volumetric flow rates shall be measured at 15-minute intervals, or at least once during the emission episode. The organic HAP or TOC concentration shall be determined from samples collected in an integrated sample over the duration of the test, or from grab samples collected simultaneously with the flow rate measurements (at approximately equal intervals of about 15 minutes). If an integrated sample is collected for laboratory analysis, the sampling rate shall be adjusted proportionally to reflect variations in flow rate.

(1) Absolute worst-case conditions are defined by the criteria presented in paragraph (c)(3)(i)(B)(1)(i) or (ii) of this section if the maximum load is the most challenging condition for the control device. Otherwise, absolute worst-case conditions are defined by the conditions in paragraph (c)(3)(i)(B)(1)(iii) of this section.

(i) The period in which the inlet to the control device will contain at least 50 percent of the maximum HAP load (in lbs) capable of being vented to the control device over any 8-hour period. An emission profile as described in paragraph (c)(3)(i)(B)(3)(i) of this section shall be used to identify the 8-hour period that includes the maximum projected HAP load.

(ii) A period of time in which the inlet to the control device will contain the highest HAP mass loading rate capable of being vented to the control device. An emission profile as described in paragraph (c)(3)(i)(B)(3)(i) of this section shall be used to identify the period of maximum HAP loading.

(iii) The period of time when the HAP loading or stream composition (including non-HAP) is most challenging for the control device. These conditions include, but are not limited to the following: periods when the stream contains the highest combined VOC and HAP load described by the emission profiles in paragraph (c)(3)(i)(B)(3) of this section; periods when the streams contain HAP constituents that approach limits of solubility for scrubbing media; or periods when the streams contain HAP constituents that approach limits of adsorptivity for carbon adsorption systems.

(2) Hypothetical worst-case conditions are simulated test conditions that, at a minimum, contain the highest hourly HAP load of emissions that would be predicted to be vented to the control device from the emissions profile described in paragraph (c)(3)(i)(B)(3)(ii) or (iii) of this section.

(3) The owner or operator shall develop an emission profile for the vent to the control device that describes the characteristics of the vent stream at the inlet to the control device under worst case conditions. The emission profile shall be developed based on any one of the procedures described in paragraphs (c)(3)(i)(B)(3)(i) through (iii) of this section, as required by paragraph (c)(3)(i)(B) of this section.

(i) The emission profile shall consider all emission episodes that could contribute to the vent stack for a period of time that is sufficient to include all processes venting to the stack and shall consider production scheduling. The profile shall describe the HAP load to the device that equals the highest sum of emissions from the episodes that can vent to the control device in any given period, not to exceed 1 hour. Emissions per episode shall be divided by the duration of the episode only if the duration of the episode is longer than 1 hour, and emissions per episode shall be calculated using the procedures specified in the following equation:

(ii) The emission profile shall consist of emissions that meet or exceed the highest emissions that would be expected under actual processing conditions. The profile shall describe equipment configurations used to generate the emission events, volatility of materials processed in the equipment, and the rationale used to identify and characterize the emission events. The emissions may be based on using compounds more volatile than compounds actually used in the process(es), and the emissions may be generated from all equipment in the process(es) or only selected equipment.

(iii) The emission profile shall consider the capture and control system limitations and the highest emissions that can be routed to the control device, based on maximum flow rate and concentrations possible because of limitations on conveyance and control equipment (e.g., fans, LEL alarms and safety bypasses).

(4) Three runs, each at a minimum of the complete duration of the batch venting episode or 1 hour, whichever is shorter, and a maximum of 8 hours, are required for performance testing. Each run shall occur over the same worst-case conditions, as defined in paragraph (c)(3)(i)(B) of this section.

(5) If a condenser is used to control the process vent stream(s), the worst case emission episode(s) shall represent a period of time in which a process vent from the batch cycle or combination of cycles (if more than one cycle is vented through the same process vent) will require the maximum heat removal capacity, in Btu/hr, to cool the process vent stream to a temperature that, upon calculation of HAP concentration, will yield the required removal efficiency for the entire cycle. The calculation of maximum heat load shall be based on the emission profile described in paragraph (c)(3)(i)(B)(3) of this section that will allow calculation of sensible and latent heat loads.

(ii)

The concentration of either TOC (minus methane or ethane) or total organic HAP (of the HAP of concern) shall be calculated according to paragraph (c)(3)(ii)(A) or (B) of this section.

(A)

The TOC concentration (CTOC) is the sum of the concentrations of the individual components and shall be computed for each run using the following equation:

(B)

The total organic HAP concentration (CHAP) shall be computed according to Equation 2 to Paragraph (c)(3)(ii)(A) of this section, except that only the organic HAP species shall be summed.

(iii)

The concentration of TOC or total organic HAP shall be corrected to 3 percent oxygen if a combustion device is used.

(A)

The emission rate correction factor or excess air, integrated sampling and analysis procedures of Method 3B of appendix A to part 60 of this chapter or the manual method in ANSI/ASME PTC 19-10-1981—Part 10 (Incorporated by reference, see § 63.14) shall be used to determine the oxygen concentration (%02d). The samples shall be taken during the same time that the TOC (minus methane or ethane) or total organic HAP samples are taken.

(B)

The concentration corrected to 3 percent oxygen shall be computed using the following equation:

(4)

Test methods. When testing is conducted to measure emissions from an affected source, the test methods specified in paragraphs (c)(4)(i) through (iv) of this section shall be used, as applicable.

(i)

For sample and velocity traverses, Method 1 or 1A of appendix A to part 60 of this chapter shall be used, as appropriate, except that references to particulate matter in Method 1A do not apply for the purposes of this subpart.

(ii)

The velocity and gas volumetric flow rate shall be determined using Method 2, 2A, 2C, or 2D of appendix A to part 60 of this chapter, as appropriate.

(iii)

The concentration measurements shall be determined using the methods described in paragraphs (c)(4)(iii)(A) through (C) of this section.

(A)

Method 18 of appendix A-6 to part 60 of this chapter or Method 320 of appendix A to this part may be used to determine the HAP concentration in any control device efficiency determination. ASTM D6420-18 (Incorporated by reference, see § 63.14) may also be used in lieu of Method 18 or Method 320, if the target compounds are all known and are all listed in Section 1.1 of ASTM D6420-18 as measurable; ASTM D6420-18 shall not be used for methane, ethane, or as a total VOC method.

(B)

Method 25 of appendix A to part 60 of this chapter may be used to determine total gaseous nonmethane organic concentration for control efficiency determinations in combustion devices.

(C)

Method 25A of appendix A to part 60 of this chapter may be used to determine the HAP or TOC concentration for control device efficiency determinations under the conditions specified in Method 25 of appendix A to part 60 of this chapter for direct measurements of an effluent with a flame ionization detector, or in demonstrating compliance with the 20 ppmv standard. The instrument shall be calibrated on methane or the predominant HAP. If calibrating on the predominant HAP, the use of Method 25A of appendix A to part 60 of this chapter shall comply with paragraphs (c)(4)(iii)(C)(1) through (3) of this section.

(1) The organic HAP used as the calibration gas for Method 25A of appendix A to part 60 of this chapter shall be the single organic HAP representing the largest percent by volume.

(2) The use of Method 25A of appendix A to part 60 of this chapter, is acceptable if the response from the high level calibration gas is at least 20 times the standard deviation of the response from the zero calibration gas when the instrument is zeroed on the most sensitive scale.

(3) The span value of the analyzer shall be less than 100 ppmv.

(iv)

Alternatively, any other method or data that have been validated according to the applicable procedures in Method 301 of appendix A to part 63 to this part may be used.

(5)

Calculation of percent reduction efficiency. The following procedures shall be used to calculate percent reduction efficiency:

(i)

Test duration shall be as specified in paragraphs (c)(3)(i)(A) through (B) of this section, as appropriate.

(ii)

The mass rate of either TOC (minus methane and ethane) or total organic HAP of the HAP of concern (Ei, Eo) shall be computed.

(A)

The following equations shall be used:

(B)

Where the mass rate of TOC is being calculated, all organic compounds (minus methane and ethane) measured by Method 18 of appendix A-6 to part 60 of this chapter, Method 320 of appendix A to this part, or ASTM D6420-18 (Incorporated by reference, see § 63.14) are summed using Equations 4 and 5 to Paragraph (c)(5)(ii)(A) of this section.

(C)

Where the mass rate of total organic HAP is being calculated, only the organic HAP species shall be summed using Equations 4 and 5 to Paragraph (c)(5)(ii)(A) of this section.

(iii)

The percent reduction in TOC (minus methane and ethane) or total organic HAP shall be calculated using the following equation:

(iv)

If the process vent stream entering a boiler or process heater with a design capacity less than 44 megawatts is introduced with the combustion air or as a secondary fuel, the weight-percent reduction of total organic HAP or TOC (minus methane and ethane) across the device shall be determined by comparing the TOC (minus methane and ethane) or total organic HAP in all combusted process vent streams and primary and secondary fuels with the TOC (minus methane and ethane) or total organic HAP, respectively, exiting the combustion device.

(d)

Determination of uncontrolled organic HAP emissions. For each process vent at a PMPU that is complying with the process vent control requirements in § 63.1425(b)(1)(i), (b)(1)(iii), (b)(2)(ii), (b)(2)(iv), (c)(1)(ii), or (d)(2) using a combustion, recovery, or recapture device, the owner or operator shall determine the uncontrolled organic HAP emissions in accordance with the provisions of this paragraph, with the exceptions noted in paragraph (d)(1) of this section. The provisions of § 63.1427(c)(1) shall be used to calculate uncontrolled epoxide emissions prior to the onset of an extended cook out.

(1)

Exemptions. Except as specified in paragraph (d)(1)(iv) of this section, the owner or operator is not required to determine uncontrolled organic HAP emissions for process vents in a PMPU if the conditions in paragraph (d)(1)(i), (ii), or (iii) of this section are met.

(i)

For PMPUs where all process vents subject to the epoxide emission reduction requirements of § 63.1425(b) are controlled at all times using a combustion, recovery, or recapture device, or extended cookout, the owner or operator is not required to determine uncontrolled epoxide emissions.

(ii)

For PMPUs where the combination of process vents from batch unit operations associated with the use of nonepoxide organic HAP to make or modify the product is subject to the Group 1 requirements of § 63.1425(c)(1), the owner or operator is not required to determine uncontrolled nonepoxide organic HAP emissions for those process vents if every process vent from a batch unit operation associated with the use of nonepoxide organic HAP to make or modify the product in the PMPU is controlled at all times using a combustion, recovery, or recapture device.

(iii)

For PMPUs where all process vents associated with catalyst extraction that are subject to the organic emission reduction requirements of § 63.1425(d)(2) are controlled at all times using a combustion, recovery, or recapture device, the owner or operator is not required to determine uncontrolled organic HAP emissions for those process vents.

(iv)

Beginning on the compliance dates specified in § 63.1422(h), paragraphs (d)(1)(i) through (iii) of this section do not apply.

(2)

Process vents from batch unit operations. The uncontrolled organic HAP emissions from an individual batch cycle for each process vent from a batch unit operation shall be determined using the procedures in the NESHAP for Group I Polymers and Resins (40 CFR part 63, subpart U), § 63.488(b)(1) through (9). Uncontrolled emissions from process vents from batch unit operations shall be determined after the exit from the batch unit operation but before any recovery device.

(3)

Process vents from continuous unit operations. The uncontrolled organic HAP emissions for each process vent from a continuous unit operation in a PMPU shall be determined at the location specified in paragraph (d)(3)(i) of this section, using the procedures in paragraph (d)(3)(ii) of this section.

(i)

For process vents subject to either the provisions for epoxide emissions in § 63.1425(b) or the provisions for organic HAP emissions from catalyst extraction in § 63.1425(d), uncontrolled emissions shall be determined after the exit from the continuous unit operation but before any recovery device.

(ii)

The owner or operator shall determine the hourly uncontrolled organic HAP emissions from each process vent from a continuous unit operation in accordance with paragraph (c)(5)(ii) of this section, except that the emission rate shall be determined at the location specified in paragraph (d)(3)(i) of this section.

(e)

Determination of organic HAP emission reduction for a PMPU.

(1)

The owner or operator shall determine the organic HAP emission reduction for process vents in a PMPU that are complying with § 63.1425(b)(1)(i), (b)(2)(ii), (c)(1)(ii), or (d)(2) using Equation 7 to Paragraph (e)(1) of this section. The organic HAP emission reduction shall be determined for each group of process vents subject to the same paragraph (i.e., paragraph (b), (c), or (d)) of § 63.1425. For instance, process vents that emit epoxides are subject to paragraph (b) of § 63.1425. Therefore, if the owner or operator of an existing affected source is complying with the 98 percent reduction requirement in § 63.1425(b)(2)(ii), the organic HAP (i.e., epoxide) emission reduction shall be determined for the group of vents in a PMPU that are subject to this paragraph.

(2)

The control efficiency, Ri, shall be assigned as specified below in paragraph (e)(2)(i), (ii), (iii), (iv), (v), or (vi) of this section.

(i)

Except as specified in paragraph (e)(2)(v) of this section, if the process vent is controlled using a flare (and the owner or operator has not previously obtained approval to assume a control efficiency greater than 98 percent in accordance with § 63.6(g)) or a combustion device specified in paragraph (b)(1), (2), (4), or (5) of this section, and a performance test has not been conducted, the control efficiency shall be assumed to be 98 percent.

(ii)

If the process vent is controlled using a combustion, recovery, or recapture device for which a performance test has been conducted in accordance with the provisions of paragraph (c) of this section, or for which a performance test that meets the requirements of paragraph (b)(3) of this section has been previously performed, the control efficiency shall be the efficiency determined by the performance test.

(iii)

If epoxide emissions from the process vent are controlled using extended cookout, the control efficiency shall be the efficiency determined in accordance with § 63.1427(e).

(iv)

Except as specified in paragraph (e)(2)(vi) of this section, if the process vent is controlled using a flare, and the owner or operator has obtained approval to assume a control efficiency greater than 98 percent in accordance with § 63.6(g), the control efficiency shall be the efficiency approved in accordance with § 63.6(g).

(v)

Beginning no later than the compliance dates specified in § 63.1422(h), if the process vent is controlled using a flare meeting the requirements specified in § 63.1436 (and the owner or operator has not previously obtained approval to assume a control efficiency greater than 98 percent in accordance with § 63.6(g)) or a combustion device specified in paragraph (b)(1), (2), (4), or (5) of this section, and a performance test has not been conducted, the control efficiency shall be assumed to be 98 percent.

(vi)

Beginning no later than the compliance dates specified in § 63.1422(h), if the process vent is controlled using a flare, and the owner or operator has obtained approval to assume a control efficiency greater than 98 percent in accordance with § 63.670(r), with exceptions noted in § 63.1436, the control efficiency shall be that approved efficiency.

(f)

Design evaluation. Except as specified in paragraph (b)(7) of this section, a design evaluation is required for those control techniques that receive less than 10 tons per year (9.1 megagrams per year) of uncontrolled organic HAP emissions from one or more PMPU, if the owner or operator has chosen not to conduct a performance test for those control techniques in accordance with paragraph (b)(6) of this section. The design evaluation shall include documentation demonstrating that the control technique being used achieves the required control efficiency under worst-case conditions, as determined from the emission profile described in § 63.1426(c)(3)(i)(B)(3)(i).

(1)

Except for ECO whose design evaluation is presented in paragraph (f)(2) of this section, to demonstrate that a control technique meets the required control efficiency, a design evaluation shall address the composition and organic HAP concentration of the vent stream, immediately preceding the use of the control technique. A design evaluation shall also address other vent stream characteristics and control technique operating parameters, as specified in any one of paragraphs (f)(1)(i) through (vi) of this section, depending on the type of control technique that is used. If the vent stream is not the only inlet to the control technique, the owner or operator shall also account for all other vapors, gases, and liquids, other than fuels, received into the control technique from one or more PMPUs, for purposes of the efficiency determination.

(i)

For an enclosed combustion technique used to comply with the provisions of § 63.1425(b)(1), (c)(1), or (d), with a minimum residence time of 0.5 seconds and a minimum temperature of 760 °C, the design evaluation shall document that these conditions exist.

(ii)

For a combustion control technique that does not satisfy the criteria in paragraph (f)(1)(i) of this section, the design evaluation shall document the control efficiency and address the characteristics listed in paragraphs (f)(1)(ii)(A) through (C) of this section, depending on the type of control technique.

(A)

For a thermal vapor incinerator, in the design evaluation the owner or operator shall consider the autoignition temperature of the organic HAP, shall consider the vent stream flow rate, and shall establish the design minimum and average temperatures in the combustion zone and the combustion zone residence time.

(B)

For a catalytic vapor incinerator, in the design evaluation the owner or operator shall consider the vent stream flow rate and shall establish the design minimum and average temperatures across the catalyst bed inlet and outlet.

(C)

For a boiler or process heater, in the design evaluation the owner or operator shall consider the vent stream flow rate; shall establish the design minimum and average flame zone temperatures and combustion zone residence time; and shall describe the method and location where the vent stream is introduced into the flame zone.

(iii)

For a condenser, in the design evaluation the owner or operator shall consider the vent stream flow rate, relative humidity, and temperature, and shall establish the design outlet organic HAP compound concentration level, design average temperature of the exhaust vent stream, and the design average temperatures of the coolant fluid at the condenser inlet and outlet. The temperature of the gas stream exiting the condenser shall be measured and used to establish the outlet organic HAP concentration.

(iv)

For a carbon adsorption system that regenerates the carbon bed directly onsite as part of the control technique (such as a fixed-bed adsorber), in the design evaluation the owner or operator shall consider the vent stream flow rate, relative humidity, and temperature, and shall establish the design exhaust vent stream organic compound concentration level, adsorption cycle time, number and capacity of carbon beds, type and working capacity of activated carbon used for the carbon beds, design total regeneration stream mass or volumetric flow over the period of each complete carbon bed regeneration cycle, design carbon bed temperature after regeneration, design carbon bed regeneration time, and design service life of the carbon. For vacuum desorption, the pressure drop shall also be included.

(v)

For a carbon adsorption system that does not regenerate the carbon bed directly onsite as part of the control technique (such as a carbon canister), in the design evaluation the owner or operator shall consider the vent stream mass or volumetric flow rate, relative humidity, and temperature, and shall establish the design exhaust vent stream organic compound concentration level, capacity of the carbon bed, type and working capacity of activated carbon used for the carbon bed, and design carbon replacement interval based on the total carbon working capacity of the control technique and source operating schedule.

(vi)

For a scrubber, in the design evaluation the owner or operator shall consider the vent stream composition, constituent concentrations, liquid-to-vapor ratio, scrubbing liquid flow rate and concentration, temperature, and the reaction kinetics of the constituents with the scrubbing liquid. The design evaluation shall establish the design exhaust vent stream organic compound concentration level and shall include the additional information in paragraphs (f)(1)(vi)(A) and (B) of this section for trays and a packed column scrubber.

(A)

Type and total number of theoretical and actual trays.

(B)

Type and total surface area of packing for entire column and for individual packed sections, if the column contains more than one packed section.

(2)

For ECO, the design evaluation shall establish the minimum duration (time) of the ECO, the maximum pressure at the end of the ECO, or the maximum epoxide concentration in the reactor liquid at the end of the ECO for each product class.

(g)

Ethylene oxide compliance determination procedures. To demonstrate compliance with the emission limits specified in § 63.1425(g) for process vents in ethylene oxide service and establish the parameter monitoring level(s), owners and operators must meet the requirements specified either paragraph (g)(1), (2), (3), or (4) of this section.

(1)

Comply with § 63.124, except:

(i)

Substitute “§ 63.100(k)(11)” with “§ 63.1422(h)”.

(ii)

Substitute “§ 63.113(j)” with “§ 63.1425(g)”.

(iii)

Substitute “§ 63.113(j)(1)” with “§ 63.1425(g)(1)”.

(iv)

Substitute “§ 63.113(j)(2)” with “§ 63.1425(g)(2) or (3)”.

(v)

Substitute “§ 63.108” with “§ 63.1436”.

(vi)

When owners or operators conduct performance tests on batch process vents using the procedures in § 63.116(c):

(A)

Substitute “the schedule in § 63.103(b)(1) of subpart F of this part” with “§ 63.1437(a)”.

(B)

The inlet sampling site shall be located after the exit from the batch unit operation but before any recovery or control device.

(C)

The minimum sampling time for each run shall be the complete duration of the batch venting episode or 1 hour, whichever is shorter, instead of that stated in § 63.116(c)(3)(i) or (c)(4)(i).

(D)

For process vents from batch unit operations, performance tests shall be conducted either at absolute worst-case conditions or hypothetical worst-case conditions as specified in § 63.1437(a)(1).

(vii)

If § 63.124(a)(4) refers to “5 pounds per year,” then substitute it for “100 pounds per year”; otherwise, § 63.124(a)(4) applies as written.

(viii)

To demonstrate compliance with § 63.124(b)(2), in lieu of an FTIR CEMS, you may choose to use a gas chromatographic CEMS meeting the requirements of Performance Specification 9 of appendix B to part 60 of this chapter. If an owner or operator uses a gas chromatographic CEMS, then the owner or operator does not need to conduct the performance testing required in § 63.124(b)(3) or the operating parameter monitoring required in paragraphs § 63.124(b)(4) through (6).

(ix)

When § 63.124 refers to § 63.148:

(A)

Substitute “§ 63.100(k)(10)” with “§ 63.1422(h)”.

(B)

Substitute “For each source as defined in § 63.101,” with “For each affected source as described in § 63.1420(a),”.

(C)

Substitute “Except for pressure relief devices subject to § 63.165(e)(4),” with “Except for pressure relief devices subject to § 63.1434(c),”.

(2)

If a combination of ECO and a control device is used for reducing ethylene oxide emissions to meet the percent emission reduction requirement or total combined process vent mass emissions limit in § 63.1425(g)(3), then the owner or operator must comply with both the requirements specified in paragraph (g)(1) of this section and the requirements specified in § 63.1427.

(3)

If ECO alone is used to comply with § 63.1425(g)(3) (i.e., no control devices are used to further reduce ethylene oxide emissions from a process vent already controlled by ECO), then the requirements specified in paragraphs (g)(1) and (2) of this section do not apply. Instead, the owner or operator is required to meet the requirements in § 63.1427.

(4)

If an owner or operator is demonstrating compliance with the combined process vent mass emissions limit in § 63.1425(g)(2) or (3) and, within the process, some process vents are uncontrolled (i.e., neither control devices nor ECO are used to reduce ethylene oxide emissions) while others are controlled, then the owner or operator must comply with paragraph (g)(1), (2), or (3) of this section for the controlled process vents and must measure ethylene oxide from the uncontrolled process vents using the procedures specified in § 63.124(a)(2)(ii) and (iii), except:

(A)

Substitute “ethylene oxide exiting the outlet of the process vent prior to any releases to the atmosphere” for “ethylene oxide entering the control device and exiting the control device”.

(B)

When the inlet of a control device is referenced in any parameter in Equation 1 to § 63.124(a)(2)(iii), it refers to the outlet of the process vent prior to any releases to the atmosphere.

(C)

Equation 2 to § 63.124(a)(2)(iii) does not apply.

Notes, amendments, and revision history

Amendments

[91 FR 13156, Mar. 18, 2026]

Source

Source: 64 FR 29439, June 1, 1999, unless otherwise noted.

Authority

Authority: 42 U.S.C. 7401 et seq.

Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.

Amendments

[91 FR 13156, Mar. 18, 2026]

§63.1427. Process vent requirements for processes using extended cookout as an epoxide emission reduction technique.

40 C.F.R. § 63.1427

(a)

Applicability of extended cookout requirements. Owners or operators of affected sources that produce polyether polyols using epoxides, and that are using ECO as a control technique to reduce epoxide emissions in order to comply with percent emission reduction requirements in § 63.1425(b)(1)(i) or (b)(2)(ii), or the requirements in § 63.1425(g)(3), shall comply with the provisions of this section. The owner or operator that is using ECO in order to comply with the emission factor requirements in § 63.1425(b)(1)(iii) or § 63.1425(b)(2)(iv) shall demonstrate that the specified emission factor is achieved by following the requirements in § 63.1431. If additional control devices are used to further reduce the HAP emissions from a process vent already controlled by ECO, then the owner or operator shall also comply with the testing, monitoring, recordkeeping, and reporting requirements associated with the additional control device, as specified in §§ 63.1426, 63.1429, and 63.1430, respectively. For the purposes of this section, replace “epoxide” with “ethylene oxide” when ECO is used to comply with the standards in § 63.1425(g)(3).

(1)

For each product class, the owner or operator shall determine the batch cycle percent epoxide emission reduction for the most difficult to control product in the product class, where the most difficult to control product is the polyether polyol that is manufactured with the slowest pressure decay curve.

(2)

The owner or operator may determine the batch cycle percent epoxide emission reduction by directly measuring the concentration of the unreacted epoxide, or by using process knowledge, reaction kinetics, and engineering knowledge, in accordance with paragraph (a)(2)(i) of this section.

(i)

If the owner or operator elects to use any method other than direct measurement, the epoxide concentration shall be determined by direct measurement for one product from each product class and compared with the epoxide concentration determined using the selected estimation method, with the exception noted in paragraph (a)(2)(ii) of this section. If the difference between the directly determined epoxide concentration and the calculated epoxide concentration is less than 25 percent, then the selected estimation method will be considered to be an acceptable alternative to direct measurement for that class.

(ii)

Except as specified in paragraph (a)(2)(iii) of this section, if uncontrolled epoxide emissions prior to the end of the ECO are less than 10 tons per year (9.1 megagrams per year), the owner or operator is not required to perform the direct measurement required in paragraph (a)(2)(i) of this section. Uncontrolled epoxide emissions prior to the end of the ECO shall be determined by the procedures in paragraph (d)(1) of this section.

(iii)

Beginning on the compliance dates specified in § 63.1422(h), paragraph (a)(2)(ii) of this section does not apply. Instead, if uncontrolled epoxide emissions prior to the end of the ECO are less than 10 tons per year (9.1 megagrams per year) and the owner or operator elects to use any method other than direct measurement, the owner or operator must comply with either paragraph (a)(2)(iii)(A) or (B) of this section.

(A)

Comply with paragraph (a)(2)(i) of this section.

(B)

For products with the same capping epoxide (i.e., the last epoxide into the reactor before the end of the epoxide feed), verify the estimation method with direct measurement of three products representing the lowest, median, and highest estimated emissions at the end of the ECO. If the difference between the directly determined epoxide concentration and the calculated epoxide concentration is less than 25 percent for each product, then the selected estimation method will be considered to be an acceptable alternative to direct measurement for all products using that capping epoxide.

(b)

Define the end of epoxide feed. The owner or operator shall define the end of the epoxide feed in accordance with paragraph (b)(1) or (2) of this section.

(1)

The owner or operator shall determine the concentration of epoxide in the reactor liquid at the point in time when all epoxide has been added to the reactor and prior to any venting. This concentration shall be determined in accordance with the procedures in paragraph (f)(1)(i) of this section.

(2)

If the conditions in paragraphs (b)(2)(i), (ii), and (iii) of this section are met, the end of the epoxide feed may be defined by the reactor epoxide partial pressure at the point in time when all epoxide reactants have been added to the reactor. This reactor epoxide partial pressure shall be determined in accordance with the procedures in paragraph (g) of this section.

(i)

No epoxide is emitted before the end of the ECO;

(ii)

Extended cookout is the only control technique to reduce epoxide emissions; and

(iii)

The owner or operator elects to determine the percent epoxide emission reduction for the ECO using reactor epoxide partial pressure in accordance with paragraph (e)(2) of this section.

(c)

Define the onset of the ECO. The owner or operator shall calculate the uncontrolled emissions for the batch cycle by calculating the epoxide emissions, if any, prior to the onset of the ECO, plus the epoxide emissions at the onset of the ECO. The onset of the ECO is defined as the point in time when the combined unreacted epoxide concentration in the reactor liquid is equal to 25 percent of the concentration of epoxides at the end of the epoxide feed, which was determined in accordance with paragraph (b) of this section.

(1)

The uncontrolled epoxide emissions for the batch cycle shall be determined using the following equation:

(2)

If the conditions in paragraphs (b)(2)(i), (ii), and (iii) of this section are met, the owner or operator may define the onset of the ECO as the point in time when the reactor epoxide partial pressure equals 25 percent of the reactor epoxide partial pressure at the end of the epoxide feed, and is not required to determine the uncontrolled epoxide emissions in accordance with paragraph (c)(1) of this section.

(d)

Determine emissions at the end of the ECO. The owner or operator shall calculate the epoxide emissions at the end of the ECO, where the end of the ECO is defined as the point immediately before the time when the reactor contents are emptied and/or the reactor vapor space purged to the atmosphere or to a combustion, recovery, or recapture device.

(1)

The epoxide emissions at the end of the ECO shall be determined using the following equation:

(2)

If the conditions in paragraphs (b)(2)(i), (ii), and (iii) of this section are met, the owner or operator may determine the reactor epoxide partial pressure at the end of the ECO instead of determining the uncontrolled epoxide emissions at the end of the ECO in accordance with paragraph (d)(1) of this section.

(e)

Determine percent epoxide emission reduction.

(1)

The owner or operator shall determine the percent epoxide emission reduction for the batch cycle using the following equation:

(2)

If the conditions in paragraphs (b)(2)(i), (ii), and (iii) of this section are met, the owner or operator may determine the percent epoxide emission reduction for the batch cycle using reactor epoxide partial pressure and the following equation, instead of using the procedures in paragraph (e)(1) of this section.

(f)

Determination of epoxide concentrations. The owner or operator shall determine the epoxide concentrations in accordance with the procedures in this paragraph.

(1)

The owner or operator shall determine the concentration of epoxide in the reactor liquid using either direct measurement in accordance with paragraph (f)(1)(i) of this section, or reaction kinetics in accordance with paragraph (f)(1)(ii) of this section. An owner or operator may also request to use an alternative methodology in accordance with paragraph (f)(1)(iii) of this section.

(i)

The owner or operator shall submit a standard operating procedure for obtaining the liquid sample, along with the test method used to determine the epoxide concentration. This information shall be submitted in the Precompliance Report. For ethylene oxide, the test method must be as described in § 63.109(b)(1) or another alternative approved by the Administrator in accordance with § 63.7(f).

(ii)

Determine the epoxide concentration in the reactor liquid using the following equation—

(iii)

If the owner/operator deems that the methods listed in paragraphs (f)(1)(i) and (ii) of this section are not appropriate for the reaction system for a PMPU, then the owner/operator may submit a request for the use of an alternative method.

(2)

The owner or operator shall determine the concentration of epoxide in the reactor vapor space using either direct measurement in accordance with paragraph (f)(2)(i) of this section, or by engineering estimation in accordance with paragraph (f)(2)(ii) of this section. An owner or operator may also request to use an alternative methodology in accordance with paragraph (f)(2)(iii) of this section.

(i)

The owner or operator shall take two representative samples from a bleed valve off the reactor's process vent. The owner or operator shall determine the total epoxide concentration using Method 18 of appendix A to part 60 of this chapter.

(ii)

Determine the epoxide concentration in the vapor space using Raoult's Law or another appropriate phase equilibrium equation and the liquid epoxide concentration, determined in accordance with paragraph (f)(1) of this section.

(iii)

(g)

Determination of pressure. The owner or operator shall determine the total pressure of the system using standard pressure measurement devices calibrated according to the manufacturer's specifications or other written procedures that provide adequate assurance that the equipment would reasonably be expected to monitor accurately.

(h)

Determination if pressure decay curves are similar. The owner or operator shall determine the pressure decay curve as defined in § 63.1423. Products with similar pressure decay curves constitute a product class. To determine if two pressure decay curves are similar when the pressure decay curves for products have different starting and finishing pressures, the owner or operator shall determine the time when the pressure has fallen to half its total pressure by using the following equation:

(i)

ECO monitoring requirements. The owner or operator using ECO shall comply with the monitoring requirements of this paragraph to demonstrate continuous compliance with this subpart. Paragraphs (i)(1) through (3) of this section address monitoring of the extended cookout.

(1)

To comply with the provisions of this section, the owner or operator shall monitor one of the parameters listed in paragraphs (i)(1)(i) through (iii) of this section, or may utilize the provision in paragraph (i)(1)(iv) of this section.

(i)

Time from the end of the epoxide feed;

(ii)

The epoxide partial pressure in the closed reactor;

(iii)

Direct measurement of epoxide concentration in the reactor liquid at the end of the ECO, when the reactor liquid is still in the reactor, or after the reactor liquid has been transferred to another vessel; or

(iv)

An owner or operator may submit a request to the Administrator to monitor a parameter other than the parameters listed in paragraphs (i)(1)(i) through (iii) of this section, as described in § 63.1439(f).

(2)

During the determination of the percent epoxide emission reduction in paragraphs (b) through (e) of this section, the owner or operator shall establish, as a level that shall be maintained during periods of operation, one of the parameters in paragraphs (i)(2)(i) through (iii) of this section, or may utilize the procedure in paragraph (i)(2)(iv) of this section, for each product class, or for each product if complying with paragraph (a)(2)(iii)(B) of this section.

(i)

The time from the end of the epoxide feed to the end of the ECO;

(ii)

The reactor epoxide partial pressure at the end of the ECO;

(iii)

The epoxide concentration in the reactor liquid at the end of the ECO, when the reactor liquid is still in the reactor, or after the reactor liquid has been transferred to another vessel; or

(iv)

An owner or operator may submit a request to the Administrator to monitor a parameter other than the parameters listed in paragraphs (i)(2)(i) through (iii) of this section, as described in § 63.1439(f).

(3)

For each batch cycle where ECO is used to reduce epoxide emissions, the owner or operator shall record the value of the monitored parameter at the end of the ECO. This parameter is then compared with the level established in accordance with paragraph (i)(2) of this section to determine if an excursion has occurred. An ECO excursion is defined as one of the situations described in paragraphs (i)(3)(i) through (v) of this section.

(i)

When the time from the end of the epoxide feed to the end of the ECO is less than the time established in paragraph (i)(2)(i) of this section;

(ii)

When the reactor epoxide partial pressure at the end of the ECO is greater than the partial pressure established in paragraph (i)(2)(ii) of this section;

(iii)

When the epoxide concentration in the reactor liquid at the end of the ECO is greater than the epoxide concentration established in paragraph (i)(2)(iii) of this section;

(iv)

When the parameter is not measured and recorded at the end of the ECO; or

(v)

When the alternative monitoring parameter is outside the range established under § 63.1439(f) for proper operation of the ECO as a control technique.

(j)

Recordkeeping requirements.

(1)

The owner or operator shall maintain the records specified in paragraphs (j)(1)(i) and (ii) of this section, for each product class. The owner or operator shall also maintain the records related to the initial determination of the percent epoxide emission reduction specified in paragraphs (j)(1)(iii) through (xi) of this section, as applicable, for each product class.

(i)

Operating conditions of the product class, including—

(A)

Pressure decay curve;

(B)

Minimum reaction temperature;

(C)

Number of reactive hydrogens in the raw material;

(D)

Minimum catalyst concentration;

(E)

Ratio of E.O./PO at the end of the epoxide feed; and

(F)

Reaction conditions, including the size of the reactor or batch.

(ii)

A listing of all products in the product class, along with the information specified in paragraphs (j)(1)(i)(A) through (F) of this section, for each product. When complying with paragraph (a)(2)(iii)(B) of this section, note the capping epoxide for each product.

(iii)

The concentration of epoxide at the end of the epoxide feed, determined in accordance with paragraph (b)(1) of this section.

(iv)

The concentration of epoxide at the onset of the ECO, determined in accordance with paragraph (c) of this section.

(v)

The uncontrolled epoxide emissions at the onset of the ECO, determined in accordance with paragraph (c)(1) of this section. The records shall also include all the background data, measurements, and assumptions used to calculate the uncontrolled epoxide emissions.

(vi)

The epoxide emissions at the end of the ECO, determined in accordance with paragraph (d)(1) of this section. The records shall also include all the background data, measurements, and assumptions used to calculate the epoxide emissions.

(vii)

The percent epoxide reduction for the batch cycle, determined in accordance with paragraph (e)(1) of this section. The records shall also include all the background data, measurements, and assumptions used to calculate the percent reduction.

(viii)

The parameter level, established in accordance with paragraph (i)(3) of this section.

(ix)

If epoxide emissions occur before the end of the ECO, the owner or operator shall maintain records of the time and duration of all such emission episodes that occur during the initial demonstration of batch cycle efficiency.

(x)

If the conditions in paragraphs (b)(2)(i), (ii), and (iii) of this section are met, the owner or operator is not required to maintain the records specified in paragraphs (j)(1)(iii) through (iv) of this section, but shall maintain the records specified in paragraphs (j)(1)(x)(A), (B), and (C) of this section.

(A)

The reactor epoxide partial pressure at the following times— (1) At end of the epoxide feed, determined in accordance with paragraph (b)(2) of this section;

(2) At the onset of the ECO, established in accordance with paragraph (c)(2) of this section; or

(3) At the end of the ECO, determined in accordance with paragraph (d)(2) of this section.

(B)

The percent epoxide reduction for the batch cycle, determined in accordance with paragraph (e)(2) of this section. The records shall also include all the measurements and assumptions used to calculate the percent reduction.

(C)

The reactor epoxide partial pressure at the end of the ECO.

(xi)

For each product class, the product that was determined to be the most difficult to control and how that determination was made. When complying with paragraph (a)(2)(iii)(B) of this section, the three products used to verify the estimation method for each capping epoxide and how those products were chosen as representative of the lowest, median, and highest estimated emissions. For each verification, keep a record of the difference between the directly determined concentration and the calculated concentration using the estimation method.

(2)

The owner or operator shall maintain the records specified in paragraphs (j)(2)(i) through (v) of this section.

(i)

For each batch cycle, the product being produced and the product class to which it belongs. When complying with paragraph (a)(2)(iii)(B) of this section, note the capping epoxide for the product produced.

(ii)

For each batch cycle, the owner or operator shall record the value of the parameter monitored in accordance with paragraph (i)(3) of this section.

(iii)

If a combustion, recovery, or recapture device is used to reduce emission in conjunction with ECO, the owner or operator shall record the information specified in § 63.1430(d) and comply with the monitoring provisions in § 63.1429 or § 63.124 as specified in § 63.1426(g).

(iv)

[Reserved]

(v)

If epoxide emissions occur before the end of the ECO, the owner or operator shall maintain records of the time and duration of all such emission episodes.

(k)

Reporting requirements. The owner or operator shall comply with the reporting requirements in this paragraph.

(1)

The information specified in paragraphs (k)(1)(i) through (ii) of this section shall be provided in the Precompliance Report, as specified in § 63.1439(e)(4).

(i)

A standard operating procedure for obtaining the reactor liquid sample and a method that will be used to determine the epoxide concentration in the liquid, in accordance with paragraph (f)(1)(i) of this section.

(ii)

A request to monitor a parameter other than those specified in paragraph (i)(1)(i), (ii), or (iii) of this section, as provided for in paragraph (i)(1)(iv) of this section.

(2)

The information specified in paragraphs (k)(2)(i) through (iv) of this section shall be provided in the Notification of Compliance Status, as specified in § 63.1439(e)(5).

(i)

For each product class, the information specified in paragraphs (k)(2)(i)(A) through (C) of this section.

(A)

The operating conditions of this product class, as specified in paragraph (j)(1)(i) of this section.

(B)

A list of all products in the product class. When complying with paragraph (a)(2)(iii)(B) of this section, note the capping epoxide for each product.

(C)

The percent epoxide emission reduction, determined in accordance with paragraph (e) of this section.

(ii)

The parameter for each product class, as determined in accordance with paragraph (i)(2) of this section.

(iii)

If a combustion, recovery, or recapture device is used in addition to ECO to reduce emissions, the information specified in § 63.1430(g)(1).

(iv)

If epoxide emissions occur before the end of the ECO, a listing of the time and duration of all such emission episodes that occur during the initial demonstration of batch cycle efficiency.

(3)

The information specified in paragraphs (k)(3)(i) through (iii) of this section shall be provided in the Periodic Report, as specified in § 63.1439(e)(6).

(i)

Reports of each batch cycle for which an ECO excursion occurred, as defined in paragraph (i)(3) of this section. At a minimum, include an identification of the PMPU as well as the start date and time of the batch cycle and the type of excursion in the Periodic Report. When the excursion is caused by a parameter exceedance, specify the operating parameter, the applicable limit, and the value of the monitored parameter at the end of the ECO.

(ii)

Notification of each batch cycle when the time and duration of epoxide emissions before the end of the ECO, recorded in accordance with paragraph (j)(2)(v) of this section, exceed the time and duration of the emission episodes during the initial epoxide emission percentage reduction determination, as recorded in paragraph (j)(1)(viii) of this section. At a minimum, include an identification of the PMPU as well as the start date and time of the batch cycle in the Periodic Report.

(iii)

If a combustion, recovery, or recapture device is used to reduce emissions, the information specified in § 63.1430(h).

(l)

New polyether polyol products. If an owner or operator wishes to utilize ECO as a control option for a polyether polyol not previously assigned to a product class and reported to the Agency in accordance with either paragraph (k)(2)(i)(B), (l)(1)(ii), or (l)(2)(iii) of this section, the owner or operator shall comply with the provisions of paragraph (l)(1) or (2) of this section.

(1)

If the operating conditions of the new polyether polyol are consistent with the operating conditions for an existing product class, the owner or operator shall comply with the requirements in paragraphs (l)(1)(i) and (ii) of this section.

(i)

The owner or operator shall update the list of products for the product class required by paragraph (j)(1)(ii) of this section, and shall record the information in paragraphs (j)(1)(i)(A) through (F) of this section for the new product.

(ii)

Within 180 days after the production of the new polyether polyol, the owner or operator shall submit a report updating the product list previously submitted for the product class. This information may be submitted along with the next Periodic Report.

(2)

If the operating conditions of the new polyether polyol do not conform with the operating characteristics of an existing product class, the owner or operator shall establish a new product class and shall comply with provisions of paragraphs (l)(2)(i) through (iii) of this section.

(i)

The owner or operator shall establish the batch cycle percent epoxide emission reduction in accordance with paragraphs (b) through (g) of this section for the product class.

(ii)

The owner or operator shall establish the records specified in paragraph (j)(1) of this section for the product class.

(iii)

Within 180 days of the production of the new polyether polyol, the owner or operator shall submit a report containing the information specified in paragraphs (k)(2)(i) and (ii) of this section.

(m)

Polyether polyol product changes. If a change in operation, as defined in paragraph (m)(1) of this section, occurs for a polyether polyol that has been assigned to a product class and reported to the Agency in accordance with paragraph (k)(2)(i)(B), (l)(1)(ii), or (l)(2)(iii) of this section, the owner or operator shall comply with the provisions of paragraphs (m)(2) through (3) of this section.

(1)

A change in operation for a polyether polyol is defined as a change in any one of the parameters listed in paragraphs (m)(1)(i) through (ix) of this section.

(i)

A significant change in reaction kinetics;

(ii)

Use of a different oxide reactant;

(iii)

Use of a different E.O./PO ratio;

(iv)

A lower reaction temperature;

(v)

A lower catalyst feed on a mole/mole fraction OH basis;

(vi)

A shorter cookout;

(vii)

A lower reactor pressure;

(viii)

A different type of reaction, (e.g., a self-catalyzed vs. catalyzed reaction); or

(ix)

A marked change in reaction conditions (e.g., a markedly different liquid level).

(2)

If the operating conditions of the product after the change in operation remain within the operation conditions of the product class to which the product was assigned, the owner or operator shall update the records specified in paragraphs (j)(1)(i)(A) through (F) of this section for the product.

(3)

If the operating conditions of the product after the change in operation are outside of the operating conditions of the product class to which the product was assigned, the owner or operator shall comply with the requirements in paragraph (m)(3)(i) or (ii) of this section, as appropriate.

(i)

If the new operating conditions of the polyether polyol are consistent with the operating conditions for another existing product class, the owner or operator shall comply with the requirements in paragraphs (m)(3)(i)(A) and (B) of this section.

(A)

The owner or operator shall update the list of products for the product class that the product is leaving, and for the product class that the product is entering, and shall record the new information in paragraphs (j)(1)(i)(A) through (F) of this section for the product.

(B)

Within 180 days after the change in operating conditions for the polyether polyol product, the owner or operator shall submit a report updating the product lists previously submitted for the product class. This information may be submitted along with the next Periodic Report.

(ii)

If the new operating conditions of the polyether polyol product do not conform with the operating characteristics of an existing product class, the owner or operator shall establish a new product class and shall comply with provisions of paragraphs (m)(3)(ii)(A) through (C) of this section.

(A)

The owner or operator shall establish the batch cycle percent epoxide emission reduction in accordance with paragraphs (b) through (g) of this section for the product class.

(B)

The owner or operator shall establish the records specified in paragraph (j)(1) of this section for the product class.

(C)

Within 180 days of the change in operating conditions for the polyether polyol, the owner or operator shall submit a report containing the information specified in paragraphs (k)(2)(i) and (ii) of this section.

Notes, amendments, and revision history

Amendments

[91 FR 13163, Mar. 18, 2026]

Source

Source: 64 FR 29439, June 1, 1999, unless otherwise noted.

Authority

Authority: 42 U.S.C. 7401 et seq.

Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.

Amendments

[91 FR 13163, Mar. 18, 2026]

§63.1428. Process vent requirements for group determination of PMPUs using a nonepoxide organic HAP to make or modify the product.

40 C.F.R. § 63.1428

(a)

Process vents from batch unit operations. The owner or operator shall determine, for each PMPU located at an affected source, if the combination of all process vents from batch unit operations that are associated with the use of nonepoxide organic HAP to make or modify the product is a Group 1 combination of batch process vents, as defined in § 63.1423. The annual uncontrolled nonepoxide organic HAP emissions, determined in accordance with paragraph (b) of this section, and annual average flow rate, determined if applicable in accordance with paragraph (c) of this section, shall be determined for all process vents from batch unit operations associated with the use of a nonepoxide organic HAP to make or modify the product, with the exception of those vents specified in paragraph (i) of this section, at the location after all applicable control techniques have been applied to reduce epoxide emissions in accordance with paragraph (a)(1) or (2) of this section.

(1)

If the owner or operator is using a combustion, recovery, or recapture device to reduce epoxide emissions, this location shall be at the exit of the combustion, recovery, or recapture device.

(2)

If the owner or operator is using ECO to reduce epoxide emissions, this location shall be at the exit from the batch unit operation. For the purpose of these determinations, the primary condenser operating as a reflux condenser on a reactor or distillation column shall be considered part of the unit operation.

(b)

Determination of annual nonepoxide organic HAP emissions. The owner or operator shall determine, for each PMPU, the total annual nonepoxide organic HAP emissions from the combination of all process vents from batch unit operations that are associated with the use of a nonepoxide organic HAP to make or modify the product in accordance with paragraphs (b)(1) and (2) of this section.

(1)

The annual nonepoxide organic HAP emissions for each process vent from a batch unit operation associated with the use of a nonepoxide organic HAP to make or modify the product shall be determined using the batch process vent procedures in the NESHAP for Group I Polymers and Resins (40 CFR part 63, subpart U), § 63.488(b).

(2)

The owner or operator shall sum the annual nonepoxide organic HAP emissions from all individual process vents from batch unit operations in a PMPU, determined in accordance with paragraph (b)(1) of this section, to obtain the total nonepoxide organic HAP emissions from the combination of process vents associated with the use of a nonepoxide organic HAP to make or modify the product, for the PMPU.

(c)

Minimum emission level exemption.

(1)

Except as specified in paragraph (c)(2) of this section, if the annual emissions of TOC or nonepoxide organic HAP from the combination of process vents from batch unit operations that are associated with the use of nonepoxide organic HAP to make or modify a polyether polyol for a PMPU are less than 11,800 kg/yr, the owner or operator of that PMPU is not required to comply with the provisions in paragraphs (d) and (e) of this section.

(2)

Beginning no later than the compliance dates specified in § 63.1422(h), paragraph (c)(1) of this section no longer applies.

(d)

Determination of average flow rate and annual average flow rate. Except as specified in paragraph (d)(3) of this section, the owner or operator shall determine, for each PMPU, the total annual average flow rate for the combination of all process vents from batch unit operations that are associated with the use of a nonepoxide organic HAP to make or modify a product in accordance with paragraphs (d)(1) and (2) of this section.

(1)

The annual average flow rate for each process vent from batch unit operations that is associated with the use of nonepoxide organic HAP to make or modify the product shall be determined using the batch process vent procedures in the NESHAP for Group I Polymers and Resins (40 CFR part 63, subpart U), § 63.488(e).

(2)

The owner or operator shall sum the annual average flow rates from the individual process vents from batch unit operations in a PMPU, determined in accordance with paragraph (d)(1) of this section, to obtain the total annual average flow rate for the combination of process vents associated with the use of a nonepoxide organic HAP to make or modify the product, for the PMPU.

(3)

Beginning no later than the compliance dates specified in § 63.1422(h), paragraphs (d)(1) and (2) of this section no longer apply.

(e)

Determination of cutoff flow rate.

(1)

Except as specified in paragraph (e)(2) of this section, for each PMPU at an affected source that uses nonepoxide organic HAP to make or modify the product, the owner or operator shall calculate the cutoff flow rate using the following equation:

(2)

Beginning no later than the compliance dates specified in § 63.1422(h), paragraph (e)(1) of this section no longer applies.

(f)

[Reserved]

(g)

Process changes affecting Group 2 combinations of process vents in a PMPU that are from batch unit operations. Whenever process changes, as described in paragraph (g)(1) of this section, are made that affect a Group 2 combination of batch process vents and that could reasonably be expected to change the group status from Group 2 to Group 1, the owner or operator shall comply with paragraphs (g)(2) and (3) of this section.

(1)

Examples of process changes include, but are not limited to, increases in production capacity or production rate, changes in feedstock type or catalyst type; or whenever there is replacement, removal, or modification of recovery equipment considered part of the batch unit operation. Any change that results in an increase in the annual nonepoxide organic HAP emissions from the estimate used in the previous group determination constitutes a process change for the purpose of these provisions. Process changes do not include: process upsets; unintentional, temporary process changes; and changes that are within the margin of variation on which the original group determination was based.

(2)

For each process affected by a process change, the owner or operator shall redetermine the group status by repeating the procedures specified in paragraphs (b) through (e) of this section, as applicable, and determining if the combination of process vents is a Group 1 combination of batch process vents, as defined in § 63.1423. Alternatively, engineering assessment, as described in § 63.488(b)(6)(i), may be used to determine the effects of the process change.

(3)

Based on the results of paragraph (g)(2) of this section, the owner or operator shall comply with either paragraph (g)(3)(i) or (ii) of this section.

(i)

If the redetermination described in paragraph (g)(2) of this section indicates that the group status of the combination of process vents from batch unit operations in a PMPU that are associated with the use of nonepoxide organic HAP to make or modify the product changes from Group 2 to Group 1 as a result of the process change, the owner or operator shall submit a report as specified in § 63.1439(e)(6)(iii)(D)(1) and shall comply with Group 1 combination of batch process vents provisions in this subpart, as specified in § 63.1425(c)(1).

(ii)

If the redetermination described in paragraph (g)(2) of this section indicates no change in group status, the owner or operator is not required to submit a report.

(h)

Process vents from continuous unit operations.

(1)

The owner or operator shall determine the total resource effectiveness (TRE) index value for each process vent from a continuous unit operation that is associated with the use of nonepoxide organic HAP to make or modify the product. To determine the TRE index value, the owner or operator shall conduct a TRE determination and calculate the TRE index value according to the HON process vent group determination procedures in § 63.115(d)(1) or (2) and the TRE equation in § 63.115(d)(3). The TRE index value shall be determined at the location after all applicable control techniques have been applied to reduce epoxide emissions in accordance with paragraph (h)(1)(i), (ii), or (iii) of this section.

(i)

If the owner or operator uses one or more nonepoxide recovery devices after all control techniques to reduce epoxide emissions, this location shall be after the last nonepoxide recovery device.

(ii)

If the owner or operator does not use a nonepoxide recovery device after a combustion, recovery, or recapture device to reduce epoxide emissions, this location shall be at the exit of the combustion, recovery, or recapture device.

(iii)

If the owner or operator does not use a nonepoxide recovery device after extended cookout to reduce epoxide emissions, this location shall be at the exit from the continuous unit operation. For the purpose of these determinations, the primary condenser operating as a reflux condenser on a reactor or distillation column shall be considered part of the unit operation.

(2)

The owner or operator of a Group 2 continuous process vent shall recalculate the TRE index value as necessary to determine whether the process vent is Group 1 or Group 2, whenever process changes are made that could reasonably be expected to change the process vent to Group 1. Examples of process changes include, but are not limited to, increases in production capacity or production rate, changes in feedstock type or catalyst type, or whenever there is replacement, removal, or addition of recovery equipment. For purposes of this paragraph, process changes do not include: process upsets; unintentional, temporary process changes; and changes that are within the range on which the original TRE calculation was based.

(i)

The TRE index value shall be recalculated based on measurements of process vent stream flow rate, TOC, and nonepoxide organic HAP concentrations, and heating values as specified in the HON process vent group determination procedures in § 63.115(a), (b), (c), and (d), as applicable, or on best engineering assessment of the effects of the change. Engineering assessments shall meet the specifications in § 63.115(d)(1).

(ii)

Where the recalculated TRE index value is less than or equal to 1.0, or, where the TRE index value before the process change was greater than 4.0 and the recalculated TRE index value is less than or equal to 4.0 but greater than 1.0, the owner or operator shall submit a report as specified in the process vent reporting and recordkeeping provisions in § 63.1430(i) or (j), and shall comply with the appropriate provisions in the process vent control requirements in § 63.1425 by the dates specified in § 63.1422 (the section describing compliance dates for sources subject to this subpart).

(iii)

Where the recalculated TRE index value is greater than 4.0, the owner or operator is not required to submit a report.

(i)

Combination of process vents from batch unit operations and process vents from continuous unit operations. If an owner or operator combines a process vent from a batch unit operation that is associated with the use of a nonepoxide organic HAP to make or modify the product with a process vent from a continuous unit operation that is associated with the use of a nonepoxide prior to the epoxide control technique, or prior to a nonepoxide recovery device that is after the epoxide control technique, then the provisions in paragraphs (i)(1) and (2) of this section shall apply.

(1)

The process vent from the batch unit operation is not required to be included in the group determination required by paragraphs (a) through (e) of this section.

(2)

The TRE index value of the combined stream shall be determined in accordance with paragraph (h) of this section, and the TRE index value shall be calculated during a period when nonepoxide organic HAP emissions are being generated by the batch unit operation.

Notes, amendments, and revision history

Amendments

[64 FR 29439, June 1, 1999, as amended at 65 FR 26501, May 8, 2000; 79 FR 17377, Mar. 27, 2014; 91 FR 13167, Mar. 18, 2026]

Source

Source: 64 FR 29439, June 1, 1999, unless otherwise noted.

Authority

Authority: 42 U.S.C. 7401 et seq.

Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.

Amendments

[64 FR 29439, June 1, 1999, as amended at 65 FR 26501, May 8, 2000; 79 FR 17377, Mar. 27, 2014; 91 FR 13167, Mar. 18, 2026]

§63.1429. Process vent monitoring requirements.

40 C.F.R. § 63.1429

(a)

Monitoring equipment requirements. The owner or operator of a process vent that uses a combustion, recovery, or recapture device to comply with the process vent control requirements in § 63.1425(b)(1), (b)(2), (c)(1), (c)(3), or (d) shall install monitoring equipment specified in paragraph (a)(1), (2), (3), (4), (5), (6), or (7) of this section, depending on the type of device used. Also, the owner or operator that uses a recovery or recapture device to comply with § 63.1425(c)(4) shall install monitoring equipment as specified in paragraph (a)(4), (5), (6), or (7) of this section. All monitoring equipment shall be installed, calibrated, maintained, and operated according to manufacturers' specifications or other written procedures that provide adequate assurance that the equipment would reasonably be expected to monitor accurately.

(1)

Where an incinerator is used, a temperature monitoring device equipped with a continuous recorder is required.

(i)

Where an incinerator other than a catalytic incinerator is used, a temperature monitoring device shall be installed in the firebox or in the ductwork immediately downstream of the firebox in a position before any substantial heat exchange occurs.

(ii)

Where a catalytic incinerator is used, temperature monitoring devices shall be installed in the gas stream immediately before and after the catalyst bed.

(2)

Except as specified in paragraph (a)(8) of this section, where a flare is used, the following monitoring equipment is required: a device (including but not limited to a thermocouple, ultraviolet beam sensor, or infrared sensor) capable of continuously detecting the presence of a pilot flame.

(3)

Where a boiler or process heater of less than 44 megawatts design heat input capacity is used, the following monitoring equipment is required: a temperature monitoring device in the firebox equipped with a continuous recorder. Any boiler or process heater in which all process vent streams are introduced with primary fuel or are used as the primary fuel is exempt from this requirement.

(4)

Where an absorber is used, a scrubbing liquid flow rate meter or a pressure monitoring device is required and should be equipped with a continuous recorder. If an acid or base absorbent is used, a pH monitoring device to monitor scrubber effluent is also required. If two or more absorbers in series are used, a scrubbing liquid flow rate meter, or a pressure monitoring device, equipped with a continuous recorder, is required for each absorber in the series. An owner or operator may submit a request to instead install the scrubbing liquid flow rate meter, or a pressure monitoring device, equipped with a continuous recorder, on only the final absorber in a series, in accordance with the alternative parameter monitoring reporting requirements in § 63.1439(f).

(5)

Where a condenser is used, a condenser exit temperature (product side) monitoring device equipped with a continuous recorder is required.

(6)

Except as specified in paragraph (a)(9) of this section, where a carbon adsorber is used, an integrating regeneration stream flow monitoring device having an accuracy of +10 percent or better, capable of recording the total regeneration stream mass or volumetric flow for each regeneration cycle, and a carbon bed temperature monitoring device, capable of recording the carbon bed temperature after each regeneration and within 15 minutes of completing any cooling cycle are required.

(7)

As an alternative to paragraphs (a)(4) through (6) of this section, the owner or operator may install an organic monitoring device equipped with a continuous recorder.

(8)

Beginning no later than the compliance dates specified in § 63.1422(h), paragraph (a)(2) of this section no longer applies and instead the owner or operator of the affected source shall comply with § 63.1436 for the flare.

(9)

Beginning no later than the compliance dates specified in § 63.1422(h), if the owner or operator vents emissions through a closed vent system to an adsorber(s) that cannot be regenerated or a regenerative adsorber(s) that is regenerated offsite, then the owner or operator shall install a system of two or more adsorber units in series and comply with the requirements specified in paragraphs (a)(9)(i) through (iii) of this section.

(i)

Conduct an initial performance test or design evaluation of the adsorber and establish the breakthrough limit and adsorber bed life.

(ii)

Monitor the HAP or TOC concentration through a sample port at the outlet of the first adsorber bed in series according to the schedule in paragraph (a)(9)(iii)(B) of this section. The owner or operator shall measure the concentration of HAP or TOC using either a portable analyzer, in accordance with Method 21 of appendix A-7 to part 60 of this chapter using methane, propane, isobutylene, or the primary HAP being controlled as the calibration gas or Method 25A of appendix A-7 to part 60 of this chapter using methane, propane, or the primary HAP being controlled as the calibration gas.

(iii)

Comply with paragraph (a)(9)(iii)(A) of this section, and comply with the monitoring frequency according to paragraph (a)(9)(iii)(B) of this section.

(A)

The first adsorber in series shall be replaced immediately when breakthrough, as defined in § 63.1423, is detected between the first and second adsorber. The original second adsorber (or a fresh canister) will become the new first adsorber and a fresh adsorber will become the second adsorber. For purposes of this paragraph (a)(9)(iii)(A), “immediately” means within eight hours of the detection of a breakthrough for adsorbers of 55 gallons or less, and within 24 hours of the detection of a breakthrough for adsorbers greater than 55 gallons. The owner or operator shall monitor at the outlet of the first adsorber within three days of replacement to confirm it is performing properly.

(B)

Based on the adsorber bed life established according to paragraph (a)(9)(i) of this section and the date the adsorbent was last replaced, conduct monitoring to detect breakthrough at least monthly if the adsorbent has more than two months of life remaining, at least weekly if the adsorbent has between two months and two weeks of life remaining, and at least daily if the adsorbent has two weeks or less of life remaining.

(b)

Alternative parameters. An owner or operator of a process vent may request approval to monitor parameters other than those listed in paragraph (a) of this section. The request shall be submitted according to the procedures specified in the process vent reporting and recordkeeping requirements in § 63.1430(j) and the alternative parameter monitoring reporting requirements in § 63.1439(f). Approval shall be requested if the owner or operator:

(1)

Uses a combustion device other than an incinerator, boiler, process heater, or flare; or

(2)

For a Group 2 continuous process vent, maintains a TRE greater than 1.0 but less than or equal to 4.0 without a recovery device or with a recovery device other than the recovery devices listed in paragraph (a) of this section; or

(3)

Uses one of the combustion, recovery, or recapture devices listed in paragraph (a) of this section, but seeks to monitor a parameter other than those specified in paragraph (a) of this section.

(c)

Monitoring of bypass lines. The owner or operator of a process vent using a process vent system that contains bypass lines that could divert a process vent stream away from the combustion, recovery, or recapture device used to comply with the process vent control requirements in § 63.1425(b), (c), or (d) shall comply with paragraphs (c)(1) or (2), and (3) of this section. Except as specified in paragraph (c)(3) of this section, equipment such as low leg drains, high point bleeds, analyzer vents, open-ended valves or lines, and pressure relief devices needed for safety purposes are not subject to paragraph (c)(1) or (2) of this section.

(1)

Properly install, maintain, and operate a flow indicator that takes a reading at least once at approximately equal intervals of about 15 minutes. Records shall be generated as specified in the process vent reporting and recordkeeping provisions in § 63.1430(d)(3). The flow indicator shall be installed at the entrance to any bypass line that could divert emissions away from the combustion, recovery, or recapture device and to the atmosphere; or

(2)

Secure the bypass line valve in the non-diverting position with a car-seal or a lock-and-key type configuration. A visual inspection of the seal or closure mechanism shall be performed at least once every month to ensure that the valve is maintained in the non-diverting position and emissions are not diverted through the bypass line. Records shall be generated as specified in the process vent reporting and recordkeeping provisions in § 63.1430(d)(4)(i).

(3)

Beginning no later than the compliance dates specified in § 63.1422(h):

(i)

The use of a bypass line at any time on a closed vent system to divert emissions (subject to the emission standards in § 63.1425) to the atmosphere or to a control device not meeting the requirements specified in this subpart is an emissions standards violation.

(ii)

The last sentence in paragraph (c) of this section no longer applies. Instead, the exemptions specified in paragraphs (c)(3)(ii)(A) and (B) of this section apply.

(A)

Except for pressure relief devices subject to § 63.1434(c), equipment such as low leg drains and equipment subject to the requirements of subpart H of this part are not subject to paragraph (c) of this section.

(B)

Open-ended valves or lines that use a cap, blind flange, plug, or second valve and follow the requirements specified in § 60.482-6(a)(2), (b), and (c) or follow requirements codified in another regulation that are the same as § 60.482-6(a)(2), (b), and (c) are not subject to paragraph (c) of this section.

(d)

Establishment of parameter monitoring levels. Parameter monitoring levels for process vents from continuous or batch unit operations using a combustion, recovery, or recapture device to comply with the process vent control requirements in § 63.1425(b), (c), or (d) shall be established as specified in paragraphs (d)(1) through (3) of this section.

(1)

For each parameter monitored under paragraphs (a) or (b) of this section, the owner or operator shall establish a level, defined as either a maximum or minimum operating parameter as denoted in Table 7 of this subpart (the table listing the operating parameters for which monitoring levels are required to be established for process vent streams), that indicates that the combustion, recovery, or recapture device is operated in a manner to ensure compliance with the provisions of this subpart. The level shall be established in accordance with the procedures specified in § 63.1438(a) through (d), as applicable. The level may be based upon a prior performance test conducted for determining compliance with a regulation promulgated by the EPA, and the owner or operator is not required to conduct a performance test under the process vent requirements for determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reductions in § 63.1426, provided that the prior performance test meets the conditions of § 63.1426(b)(3).

(2)

The established level, along with supporting documentation, shall be submitted in the Notification of Compliance Status or the operating permit application as required in the Notification of Compliance Status requirements in § 63.1439(e)(5) or in the operating permit application requirements in § 63.1439(e)(8), respectively.

(3)

The operating day shall be defined as part of establishing the parameter monitoring level and shall be submitted with the information in paragraph (d)(2) of this section. The definition of operating day shall specify the time(s) at which an operating day begins and ends.

Notes, amendments, and revision history

Amendments

[64 FR 29439, June 1, 1999, as amended at 79 FR 17377, Mar. 27, 2014; 91 FR 13168, Mar. 18, 2026]

Source

Source: 64 FR 29439, June 1, 1999, unless otherwise noted.

Authority

Authority: 42 U.S.C. 7401 et seq.

Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.

Amendments

[64 FR 29439, June 1, 1999, as amended at 79 FR 17377, Mar. 27, 2014; 91 FR 13168, Mar. 18, 2026]

§63.1430. Process vent reporting and recordkeeping requirements.

40 C.F.R. § 63.1430

(a)

Maintenance vent compliance records. For each maintenance vent opening subject to the requirements of § 63.1425(h), owners and operators must keep the applicable records specified in paragraphs (a)(1) through (5) of this section.

(1)

Owners and operators must maintain standard site procedures used to deinventory equipment for safety purposes (e.g., hot work or vessel entry procedures) to document the procedures used to meet the requirements in § 63.1425(h). The current copy of the procedures must be retained and available on-site at all times. Previous versions of the standard site procedures, as applicable, must be retained for five years.

(2)

If complying with the requirements of § 63.1425(h)(1)(i), and the lower explosive limit at the time of the vessel opening exceeds 10 percent, identification of the maintenance vent, the process units or equipment associated with the maintenance vent, the date of maintenance vent opening, and the lower explosive limit at the time of the vessel opening.

(3)

If complying with the requirements of § 63.1425(h)(1)(ii), and either the vessel pressure at the time of the vessel opening exceeds 5 psig or the lower explosive limit at the time of the active purging was initiated exceeds 10 percent, identification of the maintenance vent, the process units or equipment associated with the maintenance vent, the date of maintenance vent opening, the pressure of the vessel or equipment at the time of discharge to the atmosphere and, if applicable, the lower explosive limit of the vapors in the equipment when active purging was initiated.

(4)

If complying with the requirements of § 63.1425(h)(1)(iii), records of the estimating procedures used to determine the total quantity of VOC in the equipment and the type and size limits of equipment that contain less than 50 pounds of VOC at the time of maintenance vent opening. For each maintenance vent opening that contains greater than 50 pounds of VOC for which the deinventory procedures specified in paragraph (a)(1) of this section are not followed or for which the equipment opened exceeds the type and size limits established in the records specified in this paragraph (a)(4), records that identify the maintenance vent, the process units or equipment associated with the maintenance vent, the date of maintenance vent opening, and records used to estimate the total quantity of VOC in the equipment at the time the maintenance vent was opened to the atmosphere.

(5)

If complying with the requirements of § 63.1425(h)(1)(iv), identification of the maintenance vent, the process units or equipment associated with the maintenance vent, records documenting actions taken to comply with other applicable alternatives and why utilization of this alternative was required, the date of maintenance vent opening, the equipment pressure and lower explosive limit of the vapors in the equipment at the time of discharge, an indication of whether active purging was performed and the pressure of the equipment during the installation or removal of the blind if active purging was used, the duration the maintenance vent was open during the blind installation or removal process, and records used to estimate the total quantity of VOC in the equipment at the time the maintenance vent was opened to the atmosphere for each applicable maintenance vent opening.

(b)

Records to demonstrate compliance. The owner or operator complying with the process vent control requirements in § 63.1425(b), (c), or (d) shall keep the following records, as applicable, readily accessible:

(1)

For flares complying with § 63.11(b) to comply with the process vent control requirements in § 63.1425(b)(2)(i), (c)(1)(i), (c)(3)(i), or (d)(1), the owner or operator shall keep the records specified in paragraphs (b)(1)(i) through (iii) of this section. For flares complying with § 63.1436, the owner or operator shall comply with the recordkeeping requirements specified therein.

(i)

The flare design (i.e., steam-assisted, air-assisted, or non-assisted);

(ii)

All visible emission readings, heat content determinations, flow rate determinations, and exit velocity determinations made during the flare specification determination required by § 63.1437(c); and

(iii)

All periods during the flare specification determination required by § 63.1437(c) when all pilot flames are absent.

(2)

The following information when using a combustion, recovery, or recapture device (other than a flare) to achieve compliance with the process vent control requirements in § 63.1425(b), (c), or (d):

(i)

For a combustion, recovery, or recapture device being used to comply with a percent reduction requirement of § 63.1425(b)(1)(i), (b)(2)(ii), (c)(1)(ii), (c)(3)(ii), or (d)(2), or the annual epoxide emission limitation in § 63.1425(b)(1)(iii) or (b)(2)(iv), the percent reduction of organic HAP or TOC achieved, as determined using the procedures specified in the process vent requirements in § 63.1426;

(ii)

For a combustion device being used to comply with an outlet concentration limitation of § 63.1425(b)(1)(ii) or (b)(2)(iii), the concentration of organic HAP or TOC outlet of the combustion device, as determined using the procedures specified in the process vent requirements in § 63.1426;

(iii)

For a boiler or process heater, a description of the location at which the process vent stream is introduced into the boiler or process heater;

(iv)

For a boiler or process heater with a design heat input capacity of less than 44 megawatts and where the process vent stream is introduced with combustion air or is used as a secondary fuel and is not mixed with the primary fuel, the percent reduction of organic HAP or TOC achieved, as determined using the procedures specified in § 63.1426.

(c)

Records related to the establishment of parameter monitoring levels. For each parameter monitored according to the process vent monitoring requirements in § 63.1429(a) and either table 5 or 6 to this subpart, or for alternate parameters and/or parameters for alternate control techniques monitored according to the alternative parameter monitoring reporting requirements in § 63.1439(f) as allowed under § 63.1429(b), maintain documentation showing the establishment of the level that indicates that the combustion, recovery, or recapture device is operated in a manner to ensure compliance with the provisions of this subpart, as required by the process vent monitoring requirements in § 63.1429(d).

(d)

Records to demonstrate continuous compliance. The owner or operator that uses a combustion, recovery, or recapture device to comply with the process vent control requirements in § 63.1425(b), (c), or (d) shall keep the following records readily accessible:

(1)

Continuous records of the equipment operating parameters specified to be monitored under the process vent monitoring requirements in § 63.1429(a) as applicable, and listed in table 5 or 6 to this subpart, as applicable, or specified by the Administrator in accordance with the alternative parameter monitoring reporting requirements in § 63.1439(f), as allowed under § 63.1429(b). These records shall be kept as specified under § 63.1439(d), except as specified in paragraphs (d)(1)(i) and (ii) of this section.

(i)

For flares, the records specified in table 5 or 6 to this subpart shall be maintained in place of continuous records.

(ii)

For carbon adsorbers used for process vents from batch unit operations, the records specified in table 5 of this subpart shall be maintained in place of daily averages.

(2)

Records of the daily average value for process vents from continuous unit operations or batch unit operations of each continuously monitored parameter, except as provided in paragraphs (d)(2)(i) and (ii) of this section.

(i)

Monitoring data recorded during periods of monitoring system breakdowns, repairs, calibration checks, and zero (low-level) and high-level adjustments shall not be included in computing the daily averages. In addition, monitoring data recorded during periods of non-operation of the process (or specific portion thereof) resulting in cessation of organic HAP emissions shall not be included in computing the daily averages.

(ii)

If all recorded values for a monitored parameter during an operating day are above the minimum or below the maximum parameter monitoring level established in accordance with the process vent monitoring requirements in § 63.1429(d), the owner or operator may record that all values were above the minimum or below the maximum level established, rather than calculating and recording a daily average for that operating day.

(3)

Except as specified in paragraph (d)(6) of this section, hourly records of whether the flow indicator for bypass lines specified under § 63.1429(c)(1) was operating and whether a diversion was detected at any time during the hour. Also, records of the time(s) of all periods when the process vent was diverted from the combustion, recovery, or recapture device, or the flow indicator specified in § 63.1429(c)(1) was not operating.

(4)

Except as specified in paragraph (d)(6) of this section, where a seal or closure mechanism is used to comply with the process vent monitoring requirements for bypass lines in § 63.1429(c)(2), hourly records of flow are not required. For compliance with § 63.1429(c)(2), the owner or operator shall record whether the monthly visual inspection of the seals or closure mechanism has been done, and shall record the occurrence of all periods when the seal mechanism is broken, the bypass line valve position has changed, or the key for a lock-and-key type configuration has been checked out, and records of any car-seal that has been broken.

(5)

Records specifying the times and duration of periods of monitoring system breakdowns, repairs, calibration checks, and zero (low-level) and high level adjustments. In addition, records specifying any other periods of process or combustion, recovery, or recapture device operation when monitors are not operating.

(6)

For each flow event from a bypass line subject to the requirements in § 63.1429(c), beginning no later than the compliance dates specified in § 63.1422(h), the owner or operator shall maintain records sufficient to determine whether or not the detected flow included flow requiring control. For each flow event from a bypass line requiring control that is released either directly to the atmosphere or to a control device not meeting the requirements in this subpart, the owner or operator shall include an estimate of the volume of gas, the concentration of organic HAP in the gas, and the resulting emissions of organic HAP that bypassed the control device using process knowledge and engineering estimates.

(7)

For process vents in ethylene oxide service subject to the requirements of § 63.1426(g), owners and operators shall keep the records specified in paragraphs (d)(7)(i) and (ii) of this section in addition to those records specified elsewhere in this section.

(i)

For process vents, include all uncontrolled, undiluted ethylene oxide concentration measurements, and the calculations used to determine the total uncontrolled ethylene oxide mass emissions rate for the sum of all vent gas streams.

(ii)

If emissions are vented through a closed vent system to a non-flare control device, then the owner or operator shall keep records of all periods during which operating values are outside of the applicable operating limits specified in § 63.124(b)(4) through (6) when regulated material is being routed to the non-flare control device. The record shall specify the identification of the control device, the operating parameter, the applicable limit, and the highest (for maximum operating limits) or lowest (for minimum operating limits) value recorded during the period.

(e)

Records related to the group determination for process vents that are associated with the use of nonepoxide organic HAP to make or modify the product—

(1)

Process vents from batch unit operations. Except as provided in paragraphs (e)(1)(vi) and (vii) of this section, the owner or operator of an affected source shall maintain the records specified in paragraphs (e)(1)(i) through (v) of this section for each PMPU that uses a nonepoxide organic HAP to make or modify the product in batch unit operations. The records required to be maintained by this paragraph are limited to the information developed and used to make the group determination under the process vent requirements for processes using a nonepoxide organic HAP to make or modify the product in § 63.1428(a) through (e), as appropriate. If an owner or operator did not need to develop certain information (e.g., annual average flow rate) to determine the group status, the owner or operator is not required to develop additional information. The owner or operator may elect Group 1 status for process vents without making a Group 1/Group 2 determination. In such event, none of the records specified in paragraphs (e)(1)(i) through (v) are required.

(i)

A description of, and an emission estimate for, each batch emission episode, and the total emissions associated with one batch cycle for each unique product class made in the PMPU.

(ii)

Total annual uncontrolled TOC or nonepoxide organic HAP emissions from the combination of process vents from batch unit operations associated with the use of nonepoxide organic HAP to make or modify the product, as determined in accordance with the process vent requirements for group determinations in § 63.1428(b).

(iii)

The annual average flow rate for the combination of process vents from batch unit operations associated with the use of organic HAP to make or modify the product, as determined in accordance with the process vent requirements for group determinations in § 63.1428(d).

(iv)

The cutoff flow rate, determined in accordance with the process vent requirements for group determinations in § 63.1428(e).

(v)

The results of the PMPU group determination (i.e., whether the combination of process vents is Group 1 or Group 2).

(vi)

If the combination of all process vents from batch unit operations associated with the use of an organic HAP to make or modify the product is subject to the Group 1 batch process vent control requirements for nonepoxide HAP emissions from making or modifying the product in § 63.1425((c)(1), none of the records in paragraphs (e)(1)(i) through (v) of this section are required.

(vii)

If the total annual emissions from the combination of process vents from batch unit operations associated with the use of an organic HAP to make or modify the product are less than the thresholds specified in the definition of Group 1 combination of batch process vents in § 63.1423, only the records in paragraphs (e)(1)(i) and (ii) of this section are required.

(2)

Process vents from continuous unit operations. The owner or operator of an affected source that uses nonepoxide organic HAP to make or modify the product in continuous unit operations shall keep records regarding the measurements and calculations performed to determine the TRE index value of each process vent stream. The owner or operator of Group 1 continuous process vents that are subject to the control requirements of § 63.1425(c)(3) is not required to keep these records.

(f)

Records for Group 2 process vents that are associated with the use of nonepoxide organic HAP to make or modify the product. The following records shall be maintained for PMPUs with a Group 2 combination of batch process vents and/or one or more Group 2 continuous process vents.

(1)

Process vents from batch unit operations—emission records. The owner or operator shall maintain records of the combined total annual nonepoxide organic HAP emissions from process vents associated with the use of nonepoxide organic HAP to make or modify the product for each PMPU where the combination of these process vents is classified as Group 2.

(2)

Process vents from continuous unit operations—monitoring records for vents with TRE between 1.0 and 4.0. The owner or operator using a recovery device or other means to achieve and maintain a TRE index value greater than 1.0 but less than 4.0 as specified in the HON process vent requirements in § 63.113(a)(3) or (d) shall keep the following records readily accessible:

(i)

Continuous records of the equipment operating parameters specified to be monitored under § 63.114(b) and listed in table 5 to this subpart or specified by the Administrator in accordance with §§ 63.114(c) and 63.117(e); and

(ii)

Records of the daily average value of each continuously monitored parameter for each operating day determined according to the procedures specified in § 63.152(f). If carbon adsorber regeneration stream flow and carbon bed regeneration temperature are monitored, the records specified in table 5 to this subpart shall be kept instead of the daily averages.

(3)

Process vents from continuous unit operations—records related to process changes. The owner or operator subject to the provisions of this subpart who has elected to demonstrate compliance with the TRE index value greater than 4.0 under § 63.113(e) or greater than 1.0 under § 63.113(a)(3) or (d) shall keep readily accessible records of:

(i)

Any process changes as defined in § 63.115(e); and

(ii)

Any recalculation of the TRE index value pursuant to § 63.115(e).

(4)

Process vents from continuous unit operations—records for vents with a flow rate less than 0.005 standard cubic meter per minute. The owner or operator who elects to comply by maintaining a flow rate less than 0.005 standard cubic meter per minute under § 63.113(f), shall keep readily accessible records of:

(i)

Any process changes as defined in § 63.115(e) that increase the process vent stream flow rate;

(ii)

Any recalculation or measurement of the flow rate pursuant to § 63.115(e); and

(iii)

If the flow rate increases to 0.005 standard cubic meter per minute or greater as a result of the process change, the TRE determination performed according to the procedures of § 63.115(d).

(5)

Process vents from continuous unit operations—records for vents with an organic HAP concentration less than 50 parts per million. The owner or operator who elects to comply by maintaining an organic HAP concentration less than 50 parts per million by volume organic HAP concentration under § 63.113(g) shall keep readily accessible records of:

(i)

Any process changes as defined in § 63.115(e) that increase the organic HAP concentration of the process vent stream;

(ii)

Any recalculation or measurement of the concentration pursuant to § 63.115(e); and

(iii)

If the organic HAP concentration increases to 50 parts per million by volume or greater as a result of the process change, the TRE determination performed according to the procedures of § 63.115(d).

(g)

Notification of Compliance Status. The owner or operator of an affected source shall submit the information specified in paragraphs (g)(1) through (3) of this section, as appropriate, as part of the Notification of Compliance Status specified in § 63.1439(e)(5).

(1)

For the owner or operator complying with the process vent control requirements in § 63.1425(b), (c)(1), (c)(3), or (d), the information specified in paragraph (b) of this section related to the compliance demonstration, and the information specified in paragraph (c) of this section related to the establishment of parameter monitoring levels,

(2)

For each PMPU where the combination of process vents from batch unit operations that are associated with the use of nonepoxide organic HAP to make or modify the product is Group 2, the information related to the group determination specified in paragraph (e)(1) of this section.

(3)

For each process vent from a continuous unit operation that is associated with the use of nonepoxide organic HAP to make or modify the product that is Group 2, the information related to the group determination specified in paragraph (e)(2) of this section.

(h)

Periodic Reports. The owner or operator of an affected source shall submit Periodic Reports of the recorded information specified in paragraphs (h)(1) through (9) of this section, as appropriate, according to the schedule for submitting Periodic Reports in § 63.1439(e)(6)(i).

(1)

Reports of daily average values of monitored parameters for all operating days when the daily average values recorded under paragraph (d)(2) of this section were above the maximum, or below the minimum, level established in the Notification of Compliance Status or operating permit.

(2)

Reports of the duration of periods when monitoring data are not collected for each excursion caused by insufficient monitoring data as defined in § 63.1438(f)(1)(iv), (f)(2)(i)(B), or (f)(3)(ii).

(3)

Reports of the times and durations of all periods recorded under paragraph (d)(3) of this section when the process vent stream is diverted from the combustion, recovery, or recapture device through a bypass line and if applicable, the information in paragraph (h)(7) of this section. Include the start date, start time, and duration in hours of each period.

(4)

Reports of all periods recorded under paragraph (d)(4) of this section in which the seal mechanism is broken, the bypass line valve position has changed, or the key to unlock the bypass line valve was checked out and if applicable, the information in paragraph (h)(7) of this section. Include the start date, start time, and duration in hours of each period.

(5)

Except as specified in § 63.1436(a), reports of the times and durations of all periods recorded under paragraph (d)(1)(i) of this section in which all pilot flames of a flare were absent. Include the start date, start time, and duration in hours of each period.

(6)

Reports of all carbon bed regeneration cycles during which the parameters recorded under paragraph (d)(1)(ii) of this section were above the maximum, or below the minimum, levels established in the Notification of Compliance Status or operating permit. Include the identification of the carbon bed, the monitored parameter that was outside the established range, and the start date, start time, and duration in hours of the regeneration cycle.

(7)

Beginning no later than the compliance dates specified in § 63.1422(h), the owner or operator shall comply with this paragraph (h)(7) in addition to the requirements in paragraphs (h)(3) and (4) of this section. For bypass lines subject to the requirements in § 63.1429(c), the Periodic Report shall include the start date, start time, duration in hours, estimate of the volume of gas in standard cubic feet, the concentration of organic HAP in the gas in parts per million by volume, and the resulting mass emissions of organic HAP in pounds that bypass a control device. For periods when the flow indicator is not operating, report the start date, start time, and duration in hours.

(8)

For process vents in ethylene oxide service subject to the requirements of § 63.1426(g), the Periodic Report shall include the records for periods specified in paragraph (d)(7)(ii) of this section. Indicate the start date and time and end date and time for each period.

(9)

For any maintenance vent release exceeding the applicable limits in § 63.1425(h)(1), the Periodic Report shall include the information specified in paragraphs (h)(9)(i) through (iv) of this section. For the purposes of this reporting requirement, if an owner or operator complies with § 63.1425(h)(1)(iv), then the owner or operator shall report each venting event conducted under those provisions and include an explanation for each event as to why utilization of this alternative was required.

(i)

Identification of the maintenance vent and the equipment served by the maintenance vent.

(ii)

The date and time the maintenance vent was opened to the atmosphere.

(iii)

The LEL in percent, vessel pressure in psig, or mass in pounds of VOC in the equipment, as applicable, at the start of atmospheric venting. If the 5-psig vessel pressure option in § 63.1425(h)(1)(ii) was used and active purging was initiated while the concentration of the vapor was 10 percent or greater of its LEL, also include the concentration of the vapors at the time active purging was initiated.

(iv)

An estimate of the mass in pounds of organic HAP released during the entire atmospheric venting event.

(i)

Reports of process changes. Whenever a process change, as defined in § 63.1420(g)(3), is made that causes a Group 2 combination of batch process vents at a PMPU that are associated with the use of nonepoxide organic HAP to make or modify the product to become Group 1, the owner or operator shall submit a report within 180 days after the process change is made or the information regarding the process change is known to the owner or operator. This report may be included in the next Periodic Report or in a separate submittal to the Administrator, as specified in § 63.1439(e)(6)(iii)(D)(1). A description of the process change shall be submitted with the report.

(j)

Reporting requirements for Group 2 continuous process vents.

(1)

Whenever a process change, as defined in § 63.1420(g)(3), is made that causes a Group 2 continuous process vent with a TRE greater than 4.0 to become a Group 2 continuous process vent with a TRE less than 4.0, the owner or operator shall submit a report within 180 calendar days after the process change is made or the information regarding the process change is known, unless the flow rate is less than 0.005 standard cubic meters per minute. The report may be submitted as part of the next periodic report. The report shall include:

(i)

A description of the process change;

(ii)

The results of the recalculation of the TRE index value required under § 63.1428(h)(2), and recorded under paragraph (f)(3) of this section; and

(iii)

A statement that the owner or operator will comply with the process vent monitoring requirements specified in § 63.1429, as appropriate.

(2)

Whenever a process change, as defined in § 63.1420(g)(3), is made that causes a Group 2 continuous process vent with a flow rate less than 0.005 standard cubic meters per minute to become a Group 2 continuous process vent with a flow rate of 0.005 standard cubic meters per minute or greater, the owner or operator shall submit a report within 180 calendar days after the process change is made or the information regarding the process change is known, unless the organic HAP concentration is less than 50 ppmv. The report may be submitted as part of the next periodic report. The report shall include:

(i)

A description of the process change;

(ii)

The results of the calculation of the TRE index value required under § 63.1428(h)(2), and recorded under paragraph (f)(3) of this section; and

(iii)

A statement that the owner or operator will comply with the process vent monitoring requirements specified in § 63.1429, as appropriate.

(3)

Whenever a process change, as defined in § 63.1420(g)(3), is made that causes a Group 2 continuous process vent with an organic HAP concentration less than 50 ppmv to become a Group 2 continuous process vent with an organic HAP concentration of 50 ppmv or greater and a TRE index value less than 4.0, the owner or operator shall submit a report within 180 calendar days after the process change is made or the information regarding the process change is known, unless the flow rate is less than 0.005 standard cubic meters per minute. The report may be submitted as part of the next periodic report. The report shall include:

(i)

A description of the process change;

(ii)

The results of the calculation of the TRE index value required under § 63.1428(h)(2), and recorded under paragraph (f)(3) of this section; and

(iii)

A statement that the owner or operator will comply with the process vent monitoring requirements specified in § 63.1429, as appropriate.

(k)

Alternative requests. If an owner or operator uses a combustion, recovery, or recapture device other than those specified in the process vent monitoring requirements in § 63.1429(a)(1) through (7) and listed in table 5 or 6 to this subpart; requests approval to monitor a parameter other than those specified in § 63.1429(a)(1) through (7) and listed in table 5 or 6 to this subpart; or uses ECO and requests to monitor a parameter other than those listed in § 63.1427(i)(1)(i) through (iii), as allowed under § 63.1427(i)(1)(iv), the owner or operator shall submit a description of planned reporting and recordkeeping procedures, as specified in § 63.1439(f)(3), as part of the Precompliance Report as required under § 63.1439(e)(4), or to the Administrator as a separate submittal. The Administrator will specify appropriate reporting and recordkeeping requirements as part of the review of the Precompliance Report.

Notes, amendments, and revision history

Amendments

[91 FR 13169, Mar. 18, 2026]

Source

Source: 64 FR 29439, June 1, 1999, unless otherwise noted.

Authority

Authority: 42 U.S.C. 7401 et seq.

Source

Source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.

Amendments

[91 FR 13169, Mar. 18, 2026]

40 C.F.R. §§ 63.1425–63.1430

§63.1425. Process vent control requirements.

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§63.1426. Process vent requirements for determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a PMPU.

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§63.1427. Process vent requirements for processes using extended cookout as an epoxide emission reduction technique.

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§63.1428. Process vent requirements for group determination of PMPUs using a nonepoxide organic HAP to make or modify the product.

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§63.1429. Process vent monitoring requirements.

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§63.1430. Process vent reporting and recordkeeping requirements.

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Cite this provision

Incoming references