Tank car manway nozzles
Pipeline and Hazardous Materials Safety Administration · Apr 17, 2020 · Reference No. 19-0076
Interprets: 49 CFR § 179.4, 49 CFR § 179.200-7(b)
Reggie’s quick take
Someone asked whether ASTM A 537 steel can be used for manway nozzles on general service (non-pressure) tank cars, since it has properties similar to ASTM A 516, which is an approved material. PHMSA said no. Section 179.200-7(b) does not list A 537 for these nozzles, so it is not an oversight. Using A 537 would need a special permit, which can be applied for under 49 CFR Part 107, Subpart B. Changes to tank car specifications can also come through AAR Tank Car Committee approval under § 179.4.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
April 17, 2020
Reference No. 19-0076
This letter is in response to your June 10, 2019, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to tank car manway nozzles. Specifically, you ask for clarification on the materials of construction requirements for manway nozzles in “general service cars” (i.e., non-pressure tank cars). You note that in accordance with § 179.200-7(b), ASTM A 537 is not a listed material for construction of manway nozzles though, as you note, it has similar properties as ASTM A 516, which is a listed material.
We have paraphrased and answered your questions as follows:
Q1. You ask whether this is an oversight based on the similarities between the properties of both materials of construction.
A1. The answer is no. In accordance with § 179.200-7(b), ASTM A 537 is not a listed carbon steel material of construction for manway nozzles in non-pressure tank cars.
Q2. You mention that ASTM A 537 has better elongation and yield strengths than ASTM A 516. You also provide designs for manway nozzles for tank cars constructed of ASTM A 537 and ask whether these may be used for non-pressure tank car specifications.
A2. The answer is no. Since ASTM A 537 is not an authorized material under § 179.200-7(b), a special permit would be required to authorize use of this material. Section 179.4 provides the requirements for changes in specifications for tank cars by AAR Tank Car Committee approval or special permit. To apply for a special permit, please submit an application to the Associate Administrator for Hazardous Materials Safety in conformance with the requirements prescribed in 49 CFR Part 107, Subpart B. You may
obtain information on the special permit application process from our website at https://www.phmsa.dot.gov/approvals-and-permits/hazmat/hazardous-materials-approvals-and-permits-overview, or by calling PHMSA’s Approvals and Permits Division at (202) 366-4511.
I hope this information is helpful. Please contact us if we can be of further assistance.
Sincerely,
Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division
179.200-7(b), 179.4
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.