# Thompson Tank, Inc. — Hazardous Materials Safety Interpretation **Citation:** 15-0049 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2015-07-17 15-0049 response to Thompson Tank, Inc. concerning 178.320, 178.345. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Washington, DC 20590 1200 New Jersey Avenue, SE Safety Administration JUL 1 7 2015 Mr. David L. Thompson Thompson Tank, Inc. P.O. Box 790 Lakewood, CA 90714-0790 Ref No.: 15-0049 Dear Mr. Thompson: This is a response to your January 15, 2015 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) with regard to the manufacture of DOT specification cargo tanks. Specifically you ask if accident damage protection devices specified in § 178.345-8 (applicable to DOT 406, DOT 407 and DOT 412 cargo tanks) are considered an appurtenance or a structural support member. An accident damage protection device meets the definition of an appurtenance as defined in §§ 178.320 and 178.345-1. An accident damage protection device does not itself have lading retention or containment function and provides no structural support to the cargo tank. Accident damage protection devices if required for DOT 406, DOT 407 and DOT 412 cargo tanks must be attached to the cargo tank in accordance with the requirements of § 178.345-8(a)(3). Accident induced stresses resulting from the appropriate accident damage protection device requirements in combination with the stresses from the cargo tank operating at the MAWP may not result in a cargo tank wall stress greater than the ultimate strength of the material of construction using a safety factor of 1.3. I trust this information is helpful. If you have further questions, please do not hesitate to contact this office. Sincerely, I came 1771 Duane A. Pfund International Standards Coordinator Standards and Rulemaking Division <<>> 51T8,34E 81a)()(3) icadent damage proliste Dodd, Alice (PHMSA) 15-0049 From: Ciccarone, Michael CTR (PHMSA) Sent: Thursday, March 12, 2015 3:00 PM To: Subject: Hazmat Interps FW: Request for interpretation - Roll Over Guards. Shante/Alice, I'm not seeing this one either. From: Ciccarone, Michael CTR (PHMSA) To: Hazmat Interps Sent: Thursday, January 15, 2015 12:52 PM Subject: FW: Request for interpretation - Roll Over Guards. Shante/Alice, Please submit this for a formal letter of interpretation. Thanks, Mike From: D.L. Thompson [mailto:dlthompson@thompsontank.com] To: PHMSA HM InfoCenter Sent: Thursday, January 15, 2015 12:21 PM Subject: Request for interpretation - Roll Over Guards. Gentlemen Q1. Are the Accident Damage Protection Devices or Roll Over Guards specified in DOT 178.348-8 considered to be an Appurtenance / Attachment or a Structural Support Member. DOT 178.345-8 (a) (1) (3) requires that the accident induced stresses transferred to the tank shell with the tank operating at the MAWP be considered. Note: ASME considers these guards or devices to be an attachment and also requires that these stresses be considered. Thank you for your consideration. David L Thompson Thompson Tank, Inc. PO Box 790 Lakewood, CA. 90714 8029 Phlox Street, Downey, CA 90241 Phone 562-869-7711 Fax 562-869-7214 Toll Free 800-421-7545 1 ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `f749d60defc21574fdecfd53fc5cc0fa7c0ed7de54d469ff85bc67a2f370f7d7` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-23T22:07:51.415Z - Document slug: `phmsa-interpretation-15-0049` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Thompson Tank, Inc." ], "individuals": [ "Mr. David Thompson" ], "refIds": [ "15-0049" ], "catalogDates": [ "2015-07-17" ], "catalogParts": [ 178 ], "catalogRowCount": 3, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/66221" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "178.320", "178.345", "178.348" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/178320", "https://www.phmsa.dot.gov/regulations/title49/section/178345-1", "https://www.phmsa.dot.gov/regulations/title49/section/178345-8" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2015/150049.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2015/150049.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2015/150049.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/15-0049-651640ad0a.pdf", "pdfArtifactSha256": "e5102056c8ae28bcd3157f0d0fb9873b35c0850dc847615503855cfa781dfbf8", "extractedTextPath": "data/sources/phmsa-interpretations/15-0049-651640ad0a.v2.txt", "extractedTextSha256": "73be0edd7bd09215737e78ae9f172fbadb014599408976c97a14aa712fcc8b37", "pageCount": 2, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```