---
kind: "section"
citation: "46 C.F.R. § 64.63"
title: "46"
number: "64.63"
heading: "Minimum emergency venting capacity."
url: "https://uscodex.org/cfr/46/64.63"
---

# §64.63. Minimum emergency venting capacity.

- (a) The total emergency venting capacity (Q) of the relief devices of an uninsulated MPT must be in accordance with table 1 to § 64.63 or the following formula based upon the pressure relief device operating at a pressure not to exceed the test pressure:
- (b) The total emergency venting capacity (Q) of an insulated portable tank may have a reduction if—
  - (1) It is shown to the Coast Guard that the insulation reduces the heat transmission to the tank;
  - (2) The present reduction of the emergency venting capacity (Q) is limited to the percent reduction of the heat transmission to the tank or 50 percent, whichever is less; and
  - (3) **The insulation is sheathed.**

## Notes

### Amendments

[CGD 73-172, 39 FR 22950, June 25, 1974, as amended by CGD 84-043, 55 FR 37410, Sept. 11, 1990; 55 FR 47477, Nov. 14, 1990; USCG-2020-0634, 89 FR 50199, June 12, 2024]

### Authority

Authority: 46 U.S.C. 3306, 3703; 49 U.S.C. App. 1804; Department of Homeland Security Delegation No. 00170.1, Revision No. 01.3.

### Source

Source: CGD 73-172, 39 FR 22950, June 25, 1974, unless otherwise noted.

### Amendments

[CGD 73-172, 39 FR 22950, June 25, 1974, as amended by CGD 84-043, 55 FR 37410, Sept. 11, 1990; 55 FR 47477, Nov. 14, 1990; USCG-2020-0634, 89 FR 50199, June 12, 2024]