# Chemical Manufacturers Association — Hazardous Materials Safety Interpretation **Citation:** 99-0313 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2000-08-25 99-0313 response to Chemical Manufacturers Association concerning 173.31. ## Document text <<>> 400 Seventh St., S.W. Washington, D.C. 20590 Research and Special Programs AUG 25 2000 Administration Mr. Randy Speight Ref. No. 99-0313 Mr. Joe J. Mayhew Chemical Manufacturers Association 1300 Wilson Boulevard Arlington, VA 22209 Dear Messrs. Speight and Mayhew: I apologize for the delay in responding to your letter concerning the requirement in 49 CFR ach hazardous material shipment. This requirement has its origins in regulations of the Intersta 3.3 1(a)(1)(V1) to carefully inspect a frangible (rupture) disc in a pressure relief device prior Commerce Commission issued in 1921. The wording of this requirement was most recently revised in a final rule published on September 21, 1995, under RSPA's Docket Nos. HM-175A and 201 (60 Fed. Reg. 49098). As the language of § 173.31(d)(1)(vi) states, the purpose of this type of inspection is to check "for corrosion or damage that may alter the intended operation of the device." For that reason, in response to a comment submitted in a separate rulemaking proceeding under Docket No. HM-216 (61 Fed. Reg. 28666, 28671; June 5, 1996), we stated in the preamble that RSPA and FRA believe in order to fully inspect a rupture disc (both top and bottom), the disc must be removed from the safety vent device. It has been FRA's experience that a rupture disc may appear normal on the top side, but be severely damaged or corroded on the bottom side. You and others have raised concerns about the language of the present rule and its application to persons that forward a loaded tank car received from another location or return a tank car with residue. We anticipate initiating a rulemaking in the near future to address these concerns. Sincerely, roman yall Director, Office of Hazardous Materials Standards 990313 173, 3) - - <<>> EMA MACK CHEMICAL MANUFACTURERS ASSOCIATION $173.31 November 5, 1999 99-0313 Director, Office of Hazardous Materials Standards U.S. Department of Transportation 400 Seventa Set, I Proérams Administration Washington, D.C. 20590 Interpretation of 49 CFR § 173.31(d)(1)(vi) Dear Mr. Mazzullo: terpretation of the regulations referenced above so as to eliminate the requirement for offero I am writing to request that the Department of Transportation DOT) modify its i residue tank cars to remove rupture discs in order to conduct an inspectio member companies represent more than 90 percent of the productive capacity for basic industrial The Chemical Manufacturers Association (CMA) is a non-profit trade association whose rear and pays $4.8 billion in rail freight costs. CMA members own and lease many of the tank hemicals in the United States. The U.S. chemical industry ships 140 million tons by rail each cars used for chemical transportation. CMA members also offer and receive many tank cars The section in question requires offerors to determine that a "tank car is in proper tems, ion and safe for transportation" through an external visual inspection" that covers several (vi) The pressure relief device, including a careful inspection of the frangible disc in non- operation of the device; closing pressure relief devices, for corrosion or damage that may alter the intender areful inspection (both top and bottom of the disc) be conducted." For three reasons, CM aspect a rupture disc, the disc must be removed from the safety vent device. It is important that urges DOT to modify its interpretation so that this requirement does not apply to residue car inspections. First and foremost, residue cars usually have 99% outage and non-accidental releases involving ruptures discs are virtually non-existent with 5% or more outage. Second, DOT's interpretation could actually result in an overall decrease in safety. Rupture disc assemblies include gaskets, specialized bolting, seals, surge protection devices and other parts. Continual disassembly and reassembly of the disc system increases the chance for human error that may damage or result in improper assembly of the overall system. APublic Commitment Responsible Care 1300 WILSON BLVD., ARLINGTON, VA 22209 • TELEPHONE 703-741-5000 • FAX 703-741-6000 <<>> expose personnel to the product and impact the environment as well as contaminate the product Third, opening a residue tank car to conduct top and bottom inspections could potentially with the atmosphere (which can lead to the corrosion that concerns DOT). As applied to residue cars, the risks of top and bottom inspections of rupture discs clearly outweigh the benefits. exemption process or for RSPA to issue a revised interpretation. CMA sees two possible ways to address this situation, either to work through the CMA is aware that DOT has granted Vulcan Chemical an exemption (DOT Exemption DOT-E11761) which authorizes transportation of tank cars containing a residue of some certair "lass 8 materials without the removal of the disc for top and bottom inspection. Under this exemption, inspection of the disc, in place in the disc holder, is all that is required. CMA does not think that is the best way to address the issue because hile other offerors can apply to become parties to this exemption or request their own • The exemption process and follow-up are cumbersome. • All customers shipping back residue cars would have to become parties to the exemption. > The exemption number would have to be painted on the tank cars used to transport the product. » An exemption only remains in force for two years, requiring a renewal. The administrative burden placed upon both the shipper and the Exemptions Branch would be overwhelming in light of the number of shipments made each lay. Further, the low level of risk of exposure from a rail tank car containing a residue does not justify the effort of maintaining an exemption for each individual shipper. applies to all offerors of rail tank cars containing residue. CMA recommends and respectfully Therefore, the more appropriate solution is for RSPA to issue a revised interpretation that requests that RSPA adopt this alternative as the best way to address the issue. F41. Joe J. Mayhew Co-Leader, Distribution Team Vice President, Regulatory Affairs Cc: E. Pritchard, FRA J. Rader, FRA ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `1428d5c7bbc1881c6490a532d1690599afc14df621ea63ca466e121ceba949a6` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T11:14:22.088Z - Document slug: `phmsa-interpretation-99-0313` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Chemical Manufacturers Association" ], "individuals": [ "Mr. Randy Speight" ], "refIds": [ "99-0313" ], "catalogDates": [ "2000-08-25" ], "catalogParts": [ 173 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/65556" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "173.31", "173.31(d)(1)(vi)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/17331" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990313.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990313.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990313.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/99-0313-b5b55372fb.pdf", "pdfArtifactSha256": "c68a1914de17425bbc4202f945c47fecd7615c6310e641bc4154ddd8804bed3b", "extractedTextPath": "data/sources/phmsa-interpretations/99-0313-b5b55372fb.v2.txt", "extractedTextSha256": "a00441274593898800b9f7c43cf4f876edd2de7e1a3a344d1a57634607458ed6", "pageCount": 3, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```