# RNG Pro-Tech, Inc. — Hazardous Materials Safety Interpretation **Citation:** 99-0136 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2000-02-02 99-0136 response to RNG Pro-Tech, Inc. concerning 178.345. ## Document text <<>> f Transportatio S. Departmen 400 Seventh Street, S.W. Washington. D.C. 20590 Research and Idministration pecial Program: FEB 2 2000 Mr. Don Nelson Quality Assurance Manager Ref. No. 99-0136 1026 Western RNG Pro-Tech, Inc. P.O. Box 830 Drive TOM OSO Canada Crossfield, Alberta Dear Mr. Nelson: This is in response to your letter dated May 27, 1999, concerning cargo tank motor vehicles under the Hazardous Materials the factor of safety (FS) in the design of DOT specification inquire whether the FS reduction from 4:1 to 3.5:1, as authorized Regulations (HMR; 49 CFR Parts 171-180). Specifically, you in the 1999 Addenda of the 1998 ASME Code, is permissible under the HMR. The answer is no. in § 178.337-3 allow for the maximum stress value prescribed in The structural integrity requirements provided Section VIII of the ASME Code or 25 percent of the tensile strength of the material used. reference the 1992 edition of the ASME Code with addenda through The HMR currently incorporate by December 31, 1993, which mandates an FS of 4:1. In a recently published notice of proposed rulemaking (Docket No. HM-218; 64 ER 53165; September 30, 1999), we proposed to incorporate by reference the 1998 edition of the ASME Code for Section VIII, Division I, without the 1999 addenda. This proposal will maintain the currently authorized FS of 4:1. Any tank motor vehicle must be approved under the terms of a DOT deviation from this prescribed FS for a DOT specification cargo exemption. I trust this satisfies your inquiry. Please contact us if we can be of further assistance. Sincerely, Hathe z. Mitchell Hattie L. Mitchell Chief, Regulatory Review and Reinvention Office of Hazardous Materials Standards 990136 18365 <<>> Stevens RNG § 178.345 ProTech 1.0. Box 8830 Drive Phone: (403) 946-567 Crossfield, Alberta TOM OSI Fax: (403) 946-4358 May 27, 1999 99-0136 Mr. Tom Allan Deputy Director Office of Hazardous Materials U.S. Department of Transportation Phone: (202) 366-8553, Fax: (202) 366-3753 Re: Vessels designed with 3.5 safety factor for transports Dear Mr. Allan: I have just had a phone conversation with Mr. Ron Kirkpatrick of the Technology Division, regarding to my concerns as shown below. Department of Transportation. Mr. Kirkpatrick felt that you are the best person to talk to Based on the recent ASME Code Cases 2278, 2284 and 2290, the pressure vessels are allowed to be designed with a lower design safety factor of 3.5, versus the current factor of 4.0. RNG Pro-Tech Inc. is a manufacturer of pressure vessels and transports for hazardous materials such as LPG and NH3. We would like to know whether vessels designed per the Code Cases with a design safety factor of 3.5 are authorized for our transports per the Cargo Specifications 51, 56 and 57. tank Hazardous Material Regulations MC331, MC338, MC406, MC407, MC412 and Obviously, the use of a lower safety factor is very significant to our company and all the companies in this field. It will be greatly appreciated if we may have your response regarding to this at your earliest convenience. Looking forward to hearing from you. Truly yours, Lining Dal. Plant Manager ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `9ddf1d60615a46e28888c384d16e3d317fc2085c12c5549faecc5761ff4782af` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T18:12:42.253Z - Document slug: `phmsa-interpretation-99-0136` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "RNG Pro-Tech, Inc." ], "individuals": [ "Mr. Don Nelson" ], "refIds": [ "99-0136" ], "catalogDates": [ "2000-02-02" ], "catalogParts": [ 178 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/64461" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "178.345", "178.337" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/178345" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990136.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990136.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990136.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/99-0136-5d077ad71a.pdf", "pdfArtifactSha256": "986d9ae6ded860cff90af7762c8b13764e9cdfe5bafadc5f3aecf22702e5d3dd", "extractedTextPath": "data/sources/phmsa-interpretations/99-0136-5d077ad71a.v2.txt", "extractedTextSha256": "135aac4e13e740a2fb714f234f0b03c06c8fc6aef840b49135cebb19410f8713", "pageCount": 2, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```