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Section §178.337-9: Pressure relief devices, piping, valves, hoses, and fittings

Below are the available interpretations and guidance for the given section. To return to the list of parts, use the Parts link above. If you do not see any guidance or interpretation information below, that means there is none available for the given part/section. Return to the search page to browse additional regulations sections.

PHMSA has published several Frequently Asked Questions (FAQ) documents on regulatory topics. Please review our FAQ documents below:

Additionally PHMSA has Hazardous Materials FAQs based on letters of interpretation on the following topics:

This section of the website provides the ability to find regulations information including regulations parts, content of sections, and interpretations for regulations sections. Below is a list of parts, identified by the part number and subject. To browse sections by part, click on the subject link below. You will be taken to the eCFR website to view sections for a part.

A written regulatory interpretation, response to a question, or an opinion concerning a pipeline safety issue may be obtained by submitting a written request to the Office of Pipeline Safety (PHP–30), PHMSA, U.S. Department of Transportation, 1200 New Jersey Avenue SE., Washington, DC 20590–0001 or at the email address: In addition to email address, the requestor must include his or her return address and should also include a daytime telephone number. Requests should be submitted at least 120 days before the time the requestor needs a response.

Note: electronic submission is provided as alternative to the 49 CFR Part 190.11(b) mail-in requirement.

The regulations text of the section can be found on the eCFR website. To view the regulations text, use the link below. For assistance, please send an email to

View section 178.337-9 on the ECFR website

Interpretation Responses

Ref ID Date Company Name Individual Name Response Document
23-0035 Superior Plus Propane Mr. Tim Decker View
21-0038 Momentive Performance Materials Ms. Kirsten Pink View
19-0119 Nutrien Clayton Droste View
16-0001R Patriot Tank Lines Inc. Mark Mietz View
16-0191 Wisconsin State Patrol Karl Kronau View
17-0040 HazMat Resources, Inc. Danny Shelton View
17-0020 Keehn Service Corporation Stephen Kovacic View
11-0157 Mr. Daniel G. Shelton HazMat Resources, Inc. View
16-0001 Patriot Tank Lines Inc. Mark Mietz View
16-0001 Patriot Tank Lines Inc. Mark Mietz View
16-0090 Texas Trailer Corporation Mr. Ray Williams View
16-0033 Mr. Daniel A. Justis View
05-0195 Goodall Rubber Company Mr. Brad Ferstan View