Interpretation Response #14-0042 ([Thompson Tank Inc.] [Mr. David L. Thompson])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date: 08/22/2014

Company Name: Thompson Tank Inc.

Individual Name: Mr. David L. Thompson

Location State: CA Country: US

View the Interpretation Document

Response text:

August 22, 2014

Mr. David L. Thompson
Thompson Tank, Inc.
P.O. Box 790
Lakewood, CA 90714-0790

Ref. No. 14-0042

Dear Mr. Thompson:

This is a response to your February 26, 2014 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) with regard to the manufacture of DOT specification cargo tanks. This letter requests further clarification of a previous interpretation (Reference No. 13-0207R; see enclosed). Specifically, you seek clarification on the design, construction and certification of DOT 412 cargo tanks designed to be loaded by vacuum. You ask if a vacuum loaded DOT 412 cargo tank having a 15 psig external maximum allowable working pressure (MAWP) must be designed, constructed and certified in accordance with the ASME Code and stamped on the ASME name plate.

Specification DOT 412 cargo tanks designed to be loaded by vacuum must have a minimum external MAWP of 15 psig and a minimum internal MAWP of 25 psig in accordance with § 178.348-1(c). A DOT 412 cargo tank designed to be vacuum loaded would be required to be constructed and certified in accordance with Section VIII of the ASME Code, in accordance with § 178.348-1(e)(1) and the name plate must be stamped accordingly. This requirement does not distinguish between internal and external MAWP, therefore a DOT 412 cargo tank designed to be vacuum loaded and manufactured with an internal MAWP greater than 15 psig must be constructed and certified in accordance with the ASME Code, irrespective of the external MAWP.

I hope this information is helpful. If you have any more questions, please do not hesitate to contact this office.

Sincerely,

Robert Benedict
Chief, Standards Development
Standards and Rulemaking Division

178.34-1 (c), 1783.348-1 (e)(1)

Regulation Sections