# Hazmat Resources, Inc. — Hazardous Materials Safety Interpretation **Citation:** 13-0147 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2013-10-23 13-0147 response to Hazmat Resources, Inc. concerning 178.345, 180.407. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, D.C. 20590 OCT 2 3 20\3 Mr. Danny Shelton President Hazmat Resources, Inc. 124 Rainbow Drive, Suite 2471 Livingston, TX 77399 Ref No.: 13-0147 Dear Mr. Shelton: This responds to your July 16, 2013 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 1 71-180) applicable to pressure relief devices on specification DOT 400 series cargo tank motor vehicles. Specifically, you ask what the requirements are for testing and inspection of specification DOT 400 series cargo tank motor vehicles pertaining to pressure relief valves and pressure relief systems. As provided in§ 180.407(d)(3), all reclosing pressure reliefvalves must be externally inspected for any corrosion or damage which might prevent safe operation. Additionally, all reclosing pressure relief valves on cargo tanks carrying lading corrosive to the valve must be removed from the cargo tank for inspection and testing. Finally, each reclosing pressure relief valve required to be removed and tested must open at no less than the required set pressure and no more than 11 0 percent of the required set pressure, and must reseat to a leak-tight condition at no less than 90 percent of the start-to-discharge pressure or the pressure prescribed for the applicable cargo tank specification. Under the general design and construction requirements applicable to specification DOT 400 series cargo tank motor vehicles (see§ 178.345), the pressure relief system requirements provided in § 178.345-1 0( d) state that the set pressure of the pressure relief system is the pressure at which it starts to open, allowing discharge. The set pressure of each primary reliefva1ve must be no less than 120 percent of the maximum allowable working pressure (MA WP), and no more than 132 percent of the MA WP. Additionally, the valve must reclose at not less than 108 percent of the MA WP and remain closed at lower pressures. Finally, the set pressure of each pressure relief valve used as a secondary relief device must be not less than 120 percent of the MA WP. This standard equally applies to original construction and requalification under parts 178 and 180 of the HMR, respectively. I hope this satisfies your inquiry. Please contact us if we can be of further assistance. T. Glenn Foster Chief, Regulatory Review and Reinvention Branch Standards and Rulemaking Division <<>> Drakeford, Carolyn (PHMSA) From: Sent: To: Cc: Subject: Attachments: Importance: Betts, Charles (PHMSA) Tuesday, July 16, 2013 7:27AM Drakeford, Carolyn (PHMSA) Billings, Delmer (PHMSA) FW: Your Information on the testing of 407 vents DOT407 vent testing revised for Field Testing.pdf; Danny Shelton.vcf High l3 -0117 Carolyn- Thanks, Charles Please log and assign to a specialist for handling. Please assigned to PHH-10's Cargo Tank subject matter expert. From: Danny Shelton [mailto:shelton10104@gmail.com] Sent: Tuesday, July 16, 2013 5:02AM To: Ford, David (FMCSA); Swedberg, Richard (FMCSA); Fleener, Arthur (FMCSA) Cc: Betts, Charles (PHMSA); Mike B Thorpe; John Cannon ; 'Peter Weis'; Solomey, Joe (PHMSA); Staniszewski, Stanley (PHMSA) Subject: FW: Your Information on the testing of 407 vents Good morning gentlemen, see the following from Girard where they have revised the bench testing guidelines for their 400 series vents. A copy of that page is attached showing a revision date of July 8, 2013. They make a comment in the last sentence they are waiting on official guidance from the competent authority regarding the bench testing requirements for 400 series vents. David and Richard, can you please run this information up your chain of command and I will do the same on the public side with PHMSA. We can at least start to get the bench testing of 400 series vents clarified after 12 years of struggle. Mr. Betts, please accept this e-mail as my request to clarify the re-testing of 400 series pressure relief devices( PRO) to clearly communicate to the reader that PRO's must perform during a re-test in the same manner as the design requirements clearly identified in 178.345-10. It is my understanding and it is industry practice that the set pressure of the pressure relief system is the pressure stamped on the vent in accordance with 178.345·10(h)(3) and is the minimum pressure at which it starts to open, allowing discharge. This should be spelled out in the requirements. Re-closing pressure relief devices must perform as follows during a bench test: Each re-closing pressure relief device must open between 120 and 132 percent of the MAWP and reseat to a leak tight condition at no less than 108% of the MAWP. In addition, each re-closing pressure relief device for a DOT 406 cargo tank motor vehicle (CTMV) must open between 110 and 138 percent of the MAWP and reclose to a leak tight condition at no less than the MAWP. Regards 1 <<>> Danny Shelton HaZM3t Resources, inc Pr!!;ident 363"'-2252 ,_ &53-2252 ~· ' She!t·::m10l04@gmait<:om 124 Rainbow Dri•te, Suite 2471 Livingston,. TX 77399-1024 From: Glen Harm [mailto:GHarm@girardeguip.com] Sent: Monday, July 08, 2013 12:05 PM To: 'Danny Shelton'; Dave Girard Subject: RE: Your Information on the testing of 407 vents Dave, I have carefully gone through the example by Mr. Shelton. I understand the point he is making. However, I do not necessarily agree with it. The 180.407 can be interpreted two different ways. The way Mr. Shelton interprets it, allows a more liberal passing of the test, where by only a lower limit is applied to the range of reseating. The example he gives is 25 MAWP would reseat > 27 PSI (that is, the test technician can not pass the valve if it is lower or less than 27 PSI). Engineering at Girard has taken an approach of interpreting the 180.407 regulation to be applied to both the upper and lower Start to Discharge Pressure. There for we have always used a range for reseating. Girard does not have any issues holding this tolerance in production. Girard would not want any debate with DOT or FMCSA, that we (Girard) have improperly interpreted the regulation. So Girard has taken the "safe" route on interpreting 180.407 I have taken the liberty of revising the test page recommendation published by Girard, per Mr. Shelton's suggestion. Please review the contents, and if satisfied we can publish this more liberal tolerance for bench testing in the field. However, I would recommend that Girard maintains the stricter interpretation during the bench test at Girard, until a ruling is made by the federal regulating agency. Best regards, Glen Harm Mechanical Engineer Girard Equipment Inc. Phone:9088626300x228 Mobile 772 626 5625 From: Danny Shelton [mailto:shelton10104@gmail.com] Sent: Monday, July 08, 2013 7:01 AM To: Dave Girard Cc: Glen Harm Subject: RE: Your Information on the testing of 407 vents 2 <<>> David, alii did was give an example of how your vent is designed to operate based on the specification. And to be brief the vent must open between 120% and 132% of the MAWP so that means for a 25 MAWP tank the vent MUST open between 30 and 33. The specification for your vent goes on to say that the vent must reseat no less than 108% of the MAWP. So 108% of 25 is 27. As an example the vent is tested and it opens at 32.9. This is within the range of 30-33 so the vent opens as designed. The vent closes at 31. The design specification says the vent must close no less than 108% of the MAWP and 31 is greater than the MAWP and the vent is functioning as designed. I refer back to your reply and I just highlighted that section that permits this vent that was designed this way to also be re- tested the same way it was designed. The key word in this section is 0 R Once again it is poorly written but the design specifications are clear and concise and as long as your customers and mine are re-testing 400 series vents in accordance with the second part of 180.407(d)(3) which states: pressure prescribed for the applicable cargo tank specification, they cannot go wrong. Under your scenario in your document you say the vent must close at a pressure no greater than 29.7 but that is not the way the vent was designed. The vent was designed to reseat at a pressure less than the open pressure and greater than 27. If the vent opened at 32.9 and closed at 31 the vent is operating as designed; It does not have to reseat between 27 and 29.7, that is not what the design specification for the vent requires. 3 <<>> DOT407 VENT BENCH TESTING As prescribed by 180.407(d)(3) of the External Visual Inspection • Remove the vent from the tank. • Make sure the vent is free from any foreign matter. • Place Vent on the tester and proceed to testing procedures: Testing Procedures 1. Close the blow down valve. 2. Slowly open air input valve until needle on the pressure gauge at the rate of the second hand on your watch (approx. 1 pound per second). 3. Place hand around vent seat area to feel any escaping air. Listen for any air escaping and watch air gauge to see when the upward movement stops. When the gauge stops record the pressure, this is the SET PRESSURE. 4. Close the inlet air valve and watch gauge. The gauge needle will back down slowly and will stop this will be RESET PRESSURE. M.A.W.P SET PRESSURE (MARKED ON VENT) 25 30 35 40 30 36 42 48 SET PRESSURE (VENT MUST OPEN BETWEEN 120% and 132% ofMAWP)1 30-33 36.39.6 42-46.2 48-52.8 RESET PRESSURE (VENT MUST RESET AT 90% OF START TO DISCHARGE)2 ~273 ~32.44 ~37.85 ~43.26 1 Per 178.345-10 2 Per 180.407(d)(3) 3 Cannot be less than 27 4 Cannot be less than 32.4 5 Cannot be less than 37.8 6 Cannot be less than 43.2 Rev.7/8/13 ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `38e5816df84d23608d030ee0df1bf908ac2dd9a9c80a7d65984a0d6d21fa6c2c` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T17:21:53.232Z - Document slug: `phmsa-interpretation-13-0147` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Hazmat Resources, Inc." ], "individuals": [ "Mr. Danny Shelton" ], "refIds": [ "13-0147" ], "catalogDates": [ "2013-10-23" ], "catalogParts": [ 178, 180 ], "catalogRowCount": 2, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/65421" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "178.345", "180.407", "180.407(d)(3)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/178345-10", "https://www.phmsa.dot.gov/regulations/title49/section/180407" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2013/130147.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2013/130147.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2013/130147.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/13-0147-e6a4f0837c.pdf", "pdfArtifactSha256": "106d0edf4056f45c9eeaeb3d1f7a93c4ba9e9a2aea5b4392069f4fe4c09df70c", "extractedTextPath": "data/sources/phmsa-interpretations/13-0147-e6a4f0837c.v2.txt", "extractedTextSha256": "c5a1fe09df921e33025fc8d0fcdb5fb96a233b1fa915ea84daf1f31996db76e4", "pageCount": 5, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```