46 CFR § 64.59 - Spring loaded pressure relief valve.

---
identifier: "/us/cfr/t46/s64.59"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 64.59 - Spring loaded pressure relief valve."
title_number: 46
title_name: "Shipping"
section_number: "64.59"
section_name: "Spring loaded pressure relief valve."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "F"
subchapter_name: "MARINE ENGINEERING"
part_number: "64"
part_name: "MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
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."
regulatory_source: "CGD 73-172, 39 FR 22950, June 25, 1974, unless otherwise noted."
cfr_part: "64"
---


# 64.59 Spring loaded pressure relief valve.

A spring loaded pressure relief valve must—

(a) Be set at a nominal pressure of 125 percent of the maximum allowable working pressure;

(b) Have a minimum normal venting capacity that is sufficient to prevent the tank pressure from exceeding 137.5 percent of the maximum allowable working pressure;

(c) Close after discharge of a pressure not lower than 115 percent of the maximum allowable working pressure; and

(d) If closed, remain closed at any pressure less than 115 percent of the maximum allowable working pressure.