---
kind: "range"
citation: "40 C.F.R. §§ 63.164–63.166"
title: "40"
from: "63.164"
to: "63.166"
count: 3
url: "https://uscodex.org/cfr/40/63.164..63.166"
---

# §63.164. Standards: Compressors.

- (a) Each compressor shall be equipped with a seal system that includes a barrier fluid system and that prevents leakage of process fluid to the atmosphere, except as provided in [§ 63.162(b)](/cfr/40/63.162.md?p=b) of this subpart and paragraphs [(h)](#h) and [(i)](#i) of this section.
- (b) Each compressor seal system as required in [paragraph (a)](#a) of this section shall be:
  - (1) Operated with the barrier fluid at a pressure that is greater than the compressor stuffing box pressure; or
  - (2) Equipped with a barrier fluid system degassing reservoir that is routed to a process or fuel gas system or connected by a closed-vent system to a control device that complies with the requirements of [§ 63.172](/cfr/40/63.172.md) of this subpart; or
  - (3) **Equipped with a closed-loop system that purges the barrier fluid directly into a process stream.**
- (c) The barrier fluid shall not be in light liquid service.
- (d) Each barrier fluid system as described in [paragraphs (a) through (c)](#a..c) of this section shall be equipped with a sensor that will detect failure of the seal system, barrier fluid system, or both.
- (e)
  - (1) Each sensor as required in [paragraph (d)](#d) of this section shall be observed daily or shall be equipped with an alarm unless the compressor is located within the boundary of an unmanned plant site.
  - (2) The owner or operator shall determine, based on design considerations and operating experience, a criterion that indicates failure of the seal system, the barrier fluid system, or both.
- (f) If the sensor indicates failure of the seal system, the barrier fluid system, or both based on the criterion determined under [paragraph (e)(2)](#e-2) of this section, a leak is detected.
- (g)
  - (1) When a leak is detected, it shall be repaired as soon as practicable, but not later than 15 calendar days after it is detected, except as provided in [§ 63.171](/cfr/40/63.171.md) of this subpart.
  - (2) A first attempt at repair shall be made no later than 5 calendar days after each leak is detected.
- (h) A compressor is exempt from the requirements of [paragraphs (a) through (g)](#a..g) of this section if it is equipped with a system to capture and transport leakage from the compressor drive shaft seal to a process or a fuel gas system or to a closed vent system that captures and transports leakage from the compressor to a control device meeting the requirements of [§ 63.172](/cfr/40/63.172.md) of this subpart.
- (i) Any compressor that is designated, as described in [§ 63.181(b)(2)(ii)](/cfr/40/63.181.md?p=b-2-ii) of this subpart, to operate with an instrument reading of less than 500 parts per million above background, is exempt from the requirements of [paragraphs (a) through (h)](#a..h) of this section if the compressor:
  - (1) Is demonstrated to be operating with an instrument reading of less than 500 parts per million above background, as measured by the method specified in [§ 63.180(c)](/cfr/40/63.180.md?p=c) of this subpart; and
  - (2) Is tested for compliance with [paragraph (i)(1)](#i-1) of this section initially upon designation, annually, and at other times requested by the Administrator.

# §63.165. Standards: Pressure relief devices in gas/vapor service or light liquid service.

- (a) Except during pressure releases, each pressure relief device in gas/vapor service shall be operated with an instrument reading of less than 500 parts per million above background except as provided in [paragraph (b)](#b) of this section, as measured by the method specified in [§ 63.180(c)](/cfr/40/63.180.md?p=c). For each source as defined in [§ 63.101](/cfr/40/63.101.md), and for each source as defined in [§ 63.191](/cfr/40/63.191.md), beginning no later than the compliance dates specified in [§ 63.100(k)(10)](/cfr/40/63.100.md?p=k-10), this [paragraph (a)](#a) no longer applies and instead the owner or operator must comply with [paragraph (e)](#e) of this section.
- (b) Except as specified in [paragraph (e)](#e) of this section, comply with paragraphs [(b)(1)](#b-1) and [(b)(2)](#b-2) of this section.
  - (1) After each pressure release, the pressure relief device shall be returned to a condition indicated by an instrument reading of less than 500 parts per million above background, as soon as practicable, but no later than 5 calendar days after each pressure release, except as provided in [§ 63.171](/cfr/40/63.171.md).
  - (2) No later than 5 calendar days after the pressure release and being returned to organic HAP service, the pressure relief device shall be monitored to confirm the condition indicated by an instrument reading of less than 500 parts per million above background, as measured by the method specified in [§ 63.180(c)](/cfr/40/63.180.md?p=c).
- (c) Except as specified in [paragraph (e)](#e) of this section, any pressure relief device that is routed to a process or fuel gas system or equipped with a closed-vent system capable of capturing and transporting leakage from the pressure relief device to a control device as described in [§ 63.172](/cfr/40/63.172.md) is exempt from the requirements of paragraphs [(a)](#a) and [(b)](#b) of this section.
- (d) Except as specified in [paragraph (e)](#e) of this section, comply with paragraphs [(d)(1)](#d-1) and [(d)(2)](#d-2) of this section.
  - (1) Any pressure relief device that is equipped with a rupture disk upstream of the pressure relief device is exempt from the requirements of paragraphs [(a)](#a) and [(b)](#b) of this section, provided the owner or operator complies with the requirements in [paragraph (d)(2)](#d-2) of this section.
  - (2) After each pressure release, a rupture disk shall be installed upstream of the pressure relief device as soon as practicable, but no later than 5 calendar days after each pressure release, except as provided in [§ 63.171](/cfr/40/63.171.md).
- (e) For each source as defined in [§ 63.101](/cfr/40/63.101.md), and for each source as defined in [§ 63.191](/cfr/40/63.191.md), beginning no later than the compliance dates specified in [§ 63.100(k)(10)](/cfr/40/63.100.md?p=k-10), except as specified in [paragraph (e)(4)](#e-4) of this section, owners and operators must comply with the requirements specified in paragraphs [(e)(1)](#e-1) and [(2)](#e-2) of this section for pressure relief devices, such as relief valves or rupture disks, in organic HAP gas or vapor service instead of the pressure relief device requirements of [paragraph (a) through (d)](#a..d) of this section. Except as specified in paragraphs [(e)(4)](#e-4) and [(5)](#e-5) of this section, owners and operators must also comply with the requirements specified in paragraphs [(e)(3)](#e-3), [(6)](#e-6), [(7)](#e-7), and [(8)](#e-8) of this section for all pressure relief devices in organic HAP service.
  - (1) **Operating requirements.** Except during a pressure release, operate each pressure relief device in organic HAP gas or vapor service with an instrument reading of less than 500 ppm above background as measured by the method in [§ 63.180(c)](/cfr/40/63.180.md?p=c).
  - (2) **Pressure release requirements.** For pressure relief devices in organic HAP gas or vapor service, owners and operators must comply with the applicable requirements [paragraphs (e)(2)(i) through (iii)](#e-2-i..e-2-iii) of this section following a pressure release.
    - (i) If the pressure relief device does not consist of or include a rupture disk, conduct instrument monitoring, as specified in [§ 63.180(c)](/cfr/40/63.180.md?p=c), no later than 5 calendar days after the pressure relief device returns to organic HAP gas or vapor service following a pressure release to verify that the pressure relief device is operating with an instrument reading of less than 500 ppm.
    - (ii) If the pressure relief device includes a rupture disk, either comply with the requirements in [paragraph (e)(2)(i)](#e-2-i) of this section (and do not replace the rupture disk) or install a replacement disk as soon as practicable after a pressure release, but no later than 5 calendar days after the pressure release.
    - (iii) If the pressure relief device consists only of a rupture disk, install a replacement disk as soon as practicable after a pressure release, but no later than 5 calendar days after the pressure release. Owners and operators must not initiate startup of the equipment served by the rupture disk until the rupture disc is replaced.
  - (3) **Pressure release management.** Except as specified in paragraphs [(e)(4)](#e-4) and [(5)](#e-5) of this section, owners and operators must comply with the requirements specified in [paragraphs (e)(3)(i) through (v)](#e-3-i..e-3-v) of this section for all pressure relief devices in organic HAP service.
    - (i) Owners and operators must equip each affected pressure relief device with a device(s) or use a monitoring system that is capable of:
      - (A) Identifying the pressure release;
      - (B) Recording the time and duration of each pressure release; and
      - (C) **Notifying operators immediately that a pressure release is occurring.** The device or monitoring system must be either specific to the pressure relief device itself or must be associated with the process system or piping, sufficient to indicate a pressure release to the atmosphere. Examples of these types of devices and systems include, but are not limited to, a rupture disk indicator, magnetic sensor, motion detector on the pressure relief valve stem, flow monitor, or pressure monitor.
    - (ii) Owners and operators must apply at least three redundant prevention measures to each affected pressure relief device and document these measures. Examples of prevention measures include:
      - (A) Flow, temperature, liquid level and pressure indicators with deadman switches, monitors, or automatic actuators. Independent, non-duplicative systems within this category count as separate redundant prevention measures.
      - (B) Documented routine inspection and maintenance programs and/or operator training (maintenance programs and operator training may count as only one redundant prevention measure).
      - (C) **Inherently safer designs or safety instrumentation systems.**
      - (D) **Deluge systems.**
      - (E) Staged relief system where the initial pressure relief device (with lower set release pressure) discharges to a flare or other closed vent system and control device.
    - (iii) If any affected pressure relief device releases to atmosphere as a result of a pressure release event, owners and operators must perform root cause analysis and corrective action analysis according to the requirement in [paragraph (e)(6)](#e-6) of this section and implement corrective actions according to the requirements in [paragraph (e)(7)](#e-7) of this section. Owners and operators must also calculate the quantity of organic HAP released during each pressure release event and report this quantity as required in [§ 63.182(d)(2)(xviii)](/cfr/40/63.182.md?p=d-2-xviii). Calculations may be based on data from the pressure relief device monitoring alone or in combination with process parameter monitoring data and process knowledge.
    - (iv) Owners and operators must determine the total number of release events that occurred during the calendar year for each affected pressure relief device separately.
    - (v) Except for pressure relief devices described in paragraphs [(e)(4)](#e-4) and [(5)](#e-5) of this section, the following release events from an affected pressure relief device are a violation of the pressure release management work practice standards.
      - (A) Except as specified in [paragraph (e)(3)(v)(D)](#e-3-v-D) of this section, any release event for which the root cause of the event was determined to be operator error or poor maintenance.
      - (B) Except as specified in [paragraph (e)(3)(v)(D)](#e-3-v-D) of this section, a second release event from a single pressure relief device in a 3 calendar year period for the same root cause for the same equipment.
      - (C) Except as specified in [paragraph (e)(3)(v)(D)](#e-3-v-D) of this section, a third release event from a single pressure relief device in a 3 calendar year period for any reason.
      - (D) [Paragraphs (e)(3)(v)(A) through (e)(3)(v)(C)](#e-3-v-A..e-3-v-C) of this section do not apply to pressure relief devices in ethylene oxide service, as defined in [§ 63.101](/cfr/40/63.101.md); instead, any release event from an affected pressure relief device in ethylene oxide service is a violation of the pressure release management work practice standards.
  - (4) **Pressure relief devices routed to a control device, process, fuel gas system, or drain system.**
    - (i) If all releases and potential leaks from a pressure relief device are routed through a closed vent system to a control device, back into the process, to the fuel gas system, or to a drain system, then owners and operators are not required to comply with paragraph [(e)(1)](#e-1), [(2)](#e-2), or [(3)](#e-3) of this section.
    - (ii) Both the closed vent system and control device (if applicable) referenced in [paragraph (e)(4)(i)](#e-4-i) of this section must meet the applicable requirements specified in [§ 63.172](/cfr/40/63.172.md).
    - (iii) The drain system (if applicable) referenced in [paragraph (e)(4)(i)](#e-4-i) of this section must meet the applicable requirements specified in [§ 63.136(e)](/cfr/40/63.136.md?p=e).
  - (5) **Pressure relief devices exempted from pressure release management requirements.** The following types of pressure relief devices are not subject to the pressure release management requirements in [paragraph (e)(3)](#e-3) of this section.
    - (i) Pressure relief devices in heavy liquid service, as defined in [§ 63.161](/cfr/40/63.161.md).
    - (ii) **Thermal expansion relief valves.**
    - (iii) **Pressure relief devices on mobile equipment.**
    - (iv) Pilot-operated pressure relief devices where the primary release valve is routed through a closed vent system to a control device or back into the process, to the fuel gas system, or to a drain system.
    - (v) Balanced bellows pressure relief devices where the primary release valve is routed through a closed vent system to a control device or back into the process, to the fuel gas system, or to a drain system.
  - (6) **Root cause analysis and corrective action analysis.** A root cause analysis and corrective action analysis must be completed as soon as possible, but no later than 45 days after a release event. Special circumstances affecting the number of root cause analyses and/or corrective action analyses are provided in [paragraphs (e)(6)(i) through (iii)](#e-6-i..e-6-iii) of this section.
    - (i) Owners and operators may conduct a single root cause analysis and corrective action analysis for a single emergency event that causes two or more pressure relief devices installed on the same equipment to release.
    - (ii) [Reserved]
    - (iii) Except as provided in [paragraph (e)(6)(i)](#e-6-i) of this section, if more than one pressure relief device has a release during the same time period, an initial root cause analysis must be conducted separately for each pressure relief device that had a release. If the initial root cause analysis indicates that the release events have the same root cause(s), the initially separate root cause analyses may be recorded as a single root cause analysis and a single corrective action analysis may be conducted.
  - (7) **Corrective action implementation.** Owners and operators must conduct a root cause analysis and corrective action analysis as specified in paragraphs [(e)(3)(iii)](#e-3-iii) and (e)(6) of this section, and owners and operators must implement the corrective action(s) identified in the corrective action analysis in accordance with the applicable requirements in [paragraphs (e)(7)(i) through (iii)](#e-7-i..e-7-iii) of this section.
    - (i) All corrective action(s) must be implemented within 45 days of the event for which the root cause and corrective action analyses were required or as soon thereafter as practicable. If the owner or operator concludes that no corrective action should be implemented, the owner or operator must record and explain the basis for that conclusion no later than 45 days following the event.
    - (ii) For corrective actions that cannot be fully implemented within 45 days following the event for which the root cause and corrective action analyses were required, owners and operators must develop an implementation schedule to complete the corrective action(s) as soon as practicable.
    - (iii) No later than 45 days following the event for which a root cause and corrective action analyses were required, owners and operators must record the corrective action(s) completed to date, and, for action(s) not already completed, a schedule for implementation, including proposed commencement and completion dates.
  - (8) **Flowing pilot-operated pressure relief devices.** For affected sources that commenced construction or reconstruction on or before April 25, 2023, owners and operators are prohibited from installing a flowing pilot-operated pressure relief device or replacing any pressure relief device with a flowing pilot-operated pressure relief device after July 15, 2027. For affected sources that commenced construction or reconstruction after April 25, 2023, owners and operators are prohibited from installing and operating flowing pilot-operated pressure relief devices. For purpose of compliance with this paragraph, a flowing pilot-operated pressure relief device means the type of pilot-operated pressure relief device where the pilot discharge vent continuously releases emissions to the atmosphere when the pressure relief device is actuated.

# §63.166. Standards: Sampling connection systems.

- (a) Each sampling connection system shall be equipped with a closed-purge, closed-loop, or closed-vent system, except as provided in [§ 63.162(b)](/cfr/40/63.162.md?p=b) of this subpart. Gases displaced during filling of the sample container are not required to be collected or captured.
- (b) Each closed-purge, closed-loop, or closed-vent system as required in [paragraph (a)](#a) of this section shall:
  - (1) Return the purged process fluid directly to the process line; or
  - (2) Collect and recycle the purged process fluid to a process; or
  - (3) Be designed and operated to capture and transport the purged process fluid to a control device that complies with the requirements of [§ 63.172](/cfr/40/63.172.md) of this subpart; or
  - (4) Collect, store, and transport the purged process fluid to a system or facility identified in paragraph [(b)(4)(i)](#b-4-i), [(ii)](#b-4-ii), or [(iii)](#b-4-iii) of this section.
    - (i) A waste management unit as defined in [§ 63.111](/cfr/40/63.111.md) of [subpart G](/cfr/40/subpartG.md) of this part, if the waste management unit is subject to, and operated in compliance with the provisions of [subpart G](/cfr/40/subpartG.md) of this part applicable to group 1 wastewater streams. If the purged process fluid does not contain any organic HAP listed in Table 9 of [subpart G of part 63](/cfr/40/part63-subpartG.md), the waste management unit need not be subject to, and operated in compliance with the requirements of [40 CFR part 63](/cfr/40/part63.md), [subpart G](/cfr/40/subpartG.md) applicable to group 1 wastewater streams provided the facility has an NPDES permit or sends the wastewater to an NPDES permitted facility.
    - (ii) A treatment, storage, or disposal facility subject to regulation under 40 CFR part [262](/cfr/40/part262.md), [264](/cfr/40/part264.md), 265, or 266; or
    - (iii) A facility permitted, licensed, or registered by a State to manage municipal or industrial solid waste, if the process fluids are not hazardous waste as defined in [40 CFR part 261](/cfr/40/part261.md).
- (c) **In-situ—** sampling systems and sampling systems without purges are exempt from the requirements of paragraphs [(a)](#a) and [(b)](#b) of this section.