PHMSA Response Letter

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May 23, 2016

Mr. Alex McGonagle
UBH International
Orrell Lane
Burscough
L40 0SL
United Kingdom

Ref. No. 15-0155

Dear Mr. McGonagle:

This is in response to your July 22, 2015 e-mail, and follow-up  discussion with a member of my staff, in which you requested written clarification of the Hazardous Materials Regulations (HMR; 49 CFR parts 171-180) concerning transport provisions for portable tanks.  You ask for clarification of the requirements in §§ 178.275(f)(1) and 178.275(g)(1) as they relate to  vacuum-relief devices and pressure relief devices. Specifically, you ask if a portable tank is not fitted with a vacuum-relief device, does the requirement to prevent rupture of the shell due to a vacuum provided in § 178.275(g)(1) apply.   

For the purposes of functions covered by the HMR (i.e., transportation functions), the answer to your question is yes.  When the portable tank capacity is not less than 1,900 liters (501.9 gallons) section 178.275(g)(1) defines the functions of a pressure relief device.  Included is the requirement that pressure relief devices must have sufficient capacity to prevent rupture of the shell due to over pressurization or vacuum resulting from filling, discharging, heating of the contents, or fire.  Whether or not the portable tank has a vacuum relief valve, the portable tank design must protect against rupture due to vacuum per § 178.275(f)(1) of not less than 0.4 bar (40.0 kPa).

I trust this information is helpful.  Please do not hesitate to contact us if you have any questions.

Sincerely,

Duane Pfund
International Standards Coordinator
Standards and Rulemaking Division

178.275(f)(1), 178.275(g)(1)