# Thompson Tank, Inc. — Hazardous Materials Safety Interpretation **Citation:** 13-0207 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2014-02-18 13-0207 response to Thompson Tank, Inc. concerning 178.347, 178.348. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, D.C. 20590 FEB 1 8 2014 Mr. David L. Thompson Thompson Tank, Inc. P.O. Box 790 Lakewood, CA 90714-0790 RefNo.: 13-0207 Dear Mr. Thompson: This is a response to your October 24, 2013 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) with regard to the manufacture ofDOT specification cargo tanks. Specifically, you question whether it is permissible to manufacture a DOT 407, DOT 412, or dual specification DOT 407/412 cargo tank for vacuum loading without being constructed and certified in accordance with the Section VIII of the ASME Code for an external design pressure of at least 15 psig. In accordance with the general design and construction requirements applicable to cargo tanks, in§ 178.345-1(±), each DOT 412 cargo tank with a MAWP greater than 15 psig, and each DOT 407 cargo tank with a MA WP greater than 35 psig must be constructed and certified in conformance with Section VIII of the ASME Code, except as limited or modified by the applicable cargo tank specification. Specification DOT 412 cargo tanks designed to be loaded by vacuum must have a minimum external MAWP of 15 psig in accordance with§ 178.348-1(c). Any DOT 412 cargo tank with a MA WP greater than 15 psig must be designed, constructed and certified in conformance with Section VIII ofthe ASME Code per§ 178.348-1(e)(l). Unless a DOT 412 cargo tank was manufactured with a MA WP of exactly 15 psig (the minimum MA WP for vacuum load capable DOT 412 cargo tanks), it would also be required to be constructed and · certified in accordance with Section VIII of the ASME Code. Specification DOT 407 cargo tanks designed to be loaded by vacuum must have a minimum external design pressure of 15 psig and must be designed, constructed and certified in accordance with Section VIII ofthe ASME Code, in accordance with§ 178.347-1(c). Therefore, a DOT 407 cargo tank designed for vacuum loading would not be permitted to be manufactured without being constructed and certified in accordance with Section VIII of the ASMECode. A cargo tank built to a dual specification DOT 407/412, designed to be loaded by vacuum, must conform to both of the applicable specifications. Therefore since all DOT 407 cargo tanks designed for vacuum loading must be constructed and certified in accordance with <<>> Section VIII of the ASME Code and have a minimum external design pressure of 15 psig, the manufacture of this multi-specification cargo tank would not be permitted without fulfilling these requirements. I hope this information is helpful. If you have any more questions, please do not hesitate to contact this office. Sincerely, fkl3~ Robert Benedict Chief, Standards Development Standards and Rulemaking Division <<>> THOMPSON TANK, INC. ASME- D.O.T CERTIFICATION D.O.T. INSPECTION- TESTING DESIGN ENGINEERING • CONSTRUCTION THOlVIPSON VACUUlVI-PRESSURE UNITS October 24, 2013 U.S. DOT PHMSA Office of Hazardous Material Standards Attn: PHH-10 East building 1200 New Jersey Ave., SE. Washington, DC 20590-0001 Gentlemen, Is it permissible to manufacture a DOT -407 or a DOT -412, or a Dual Specification DOT -407 /DOT -412 Cargo Tank for vacuum loading without being constructed and certified in accordance with the ASME Code for an external design pressure of at least 1Spsi? Reference: 178.347-1 © 178.348-1 © 180.405 (f) (1) (i) ,'J Sincerely, David L. Thompson Tfiomyson Tank, Inc. SHIPPING: 8029 PHLOX STREET, DOWNEY, CA 90241 MAILING: POST OFFICE BOX 790, LAKEWOOD, CA 90714-0790 PHONE: (562) 869-7711 • FAX: (562) 869-7214 • OUT OF STATE: (800) 421-7545 ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `fbc399d80b3c4d65edb27d098fedbc6a1048f6f0bf373207e41996cf5b228d6e` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-25T04:14:51.962Z - Document slug: `phmsa-interpretation-13-0207` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Thompson Tank, Inc." ], "individuals": [ "Mr. David L. 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