# Alloy Custom Products — Hazardous Materials Safety Interpretation **Citation:** 06-0243 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2007-01-03 06-0243 response to Alloy Custom Products concerning 173.33, 177.834. ## Document text <<>> 95 sportions Washington, D.C. 20590 400 Seventh Street, S.W. Hazardous Materials Safety Pipeline and JAN .L.i Mr. Everett Snoeberger Ref. No.: 06-0243 9701 SR 25 North Alloy Custom Products Lafayette, IN 47905 Dear Mr. Snoeberger: This is in response to your October 19, 2006 letter and enclosed video regarding the use of MC-338 cargo tank motor vehicles as specified under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Your scenarios revolve around the shipment of hazardous materials in vacuum insulated MC-338 cargo tank motor vehicles. Your questions are paraphrased and answered as follows: Q1: Section 173.33(g) requires each liquid filling and liquid discharge line in ar MC-338 cargo tank to be provided with a remotely controlled internal self-closing stop valve except when the MC-338 cargo tank is used to transport argon, carbon dioxide, helium, krypton, neon, nitrogen, and xenon. Section 178.338-11(b) specifies that for MC-338 cargo tanks, each liquid filling and liquid discharge line must be provided with a shut-off valve located the line must also have a manual shut-off valve. This provision allows for either an as close to the tank as practicable and, unless the valve is manually operable at the valve, internal or an external stop valve placed as close to the tank as possible. We have found that most vacuum insulated MC-338 cargo tanks operate at temperatures below the reliable operating temperature of available internal self-closing stop valves, and currently no temperatures that may reach minus 452 °F. Therefore, is a MC-338 required to have a ranufacturer builds an internal self-closing stop valve that will operate reliably at remotely controlled internal self-closing stop valve as specified in § 173.33(g)? Al: The answer is no. MC-338 cargo tanks that utilize an external self-closing stop valve for compliance with the requirements in § 178.338-11(b) may be used to transport issue will be clarified in a future rulemaking. hazardous materials in commerce, notwithstanding the provisions in § 173.33(g). This (2: Section 177.834(j) requires cargo tanks to be transported with all valves and other closures in liquid discharge systems to be closed and free of leaks unless transported il accordance with 8 173.29(b)(2). This provision was added as a result of HM-222B (Ma 30, 1996; 61 FR 27166) to consolidate the closure requirements for cargo tanks transporting Class 3 (flammable liquid) materials, class 8 (corrosive) materials, and Division 6.1 (poisonous) materials. This rule did not consider the impact this provision would have on MC-338 cargo tanks that transport cryogenic liquids. These tanks have 113.33(9) 177.834 060243 <<>> external self-closing valves that are normally transported in an open position. These Subsequently, these valves require a large amount of force and effort to open. As a result, valves are designed to close with a tremendous amount of force to ensure proper closure. the potential for physical injury to employee personnel is increased and the ability of the valve system to operate is potentially compromised as a result of repeated cycling (opening, closing, and testing). Does §177.834(i) permit emergency self-closing valves on MC-338 cargo tanks to be either open or closed during transit? 42: The answer is yes. External emergency self-closing valves on MC-338 cargo tanks containing cryogenic liquids may remain either open or closed during transit. We will clarify this issue in a future rulemaking. contact this office. .. hope this information is helpful. If you have further questions, please do not hesitate to Sincerely, Hotte Moha Hattie Mitchell Chief, Regulatory Review and Reinvention Office of Hazardous Materials, Standards <<>> Satterth waite 113.359 Alloy Custom Products InC. Cargo Tank 3177.837 Mailing: P. O. Box 198, St. Rd. 25S Delphi, IN 46923-0198 Shipping: 9701 St. Rd. 25 N Lafayette, IN 47905-4394 06-0243 Engineering, Fabricating and Repair of ASME Code Pressure Vessels & Process Equipment and Cryogenic 800-359-2556 E-mail: sales@alloycusfomproducts.com FAX: 765-564-6032 WEB: www.alloycustomproducts.co Page 1 of 3 Director, Office of Hazardous Materials J.S. DOT / PHMSA (PHH-10] 10/19/2006 Washington, D.C. 20590-0001 100 7* Street S.W Mr. Edward T. Mazzullo Dear Mr. Mazzullo, requirements in 177.834(j) requiring that all valves in liquid discharge systems are closed. the requirements of 49 CFR 173.33(g) which currently require these tanks to be equipped with internal We respectfully request an interpretation that vacuum insulated MC-338 cargo tanks be excepted from self closing emergency stop valves. emergency stop valve. The design and construction requirements in 49 CFR 178.338-11( b) and (c changed to permit MC-338 cargo tanks to be equipped with either an internal or external self closing that may be open or closed during transit. Background 1. Availability of suitable components; b. a. External self closing stop valves Internal valves 2. Normal operating procedures a. External self closing stop valves are open during transit because they are extremely 3. Intent of the rules as they were originally written difficult to be reset by the driver once they are closed. a. reliably closes with authority and stops the flow of liquid from lines in the event of an The original intent of the regulation was to provide these cargo tanks with a valve tha emergency. <<>> Page 2 of 3 closing stop valve but it is impossible to comply with on all MC-338 cargo tanks. Most vacuum insulated First and foremost 49 CFR Part 173.33 (g) requires that all MC-338 cargo tanks to have an internal self internal self closing stop valves and there is currently no manufacturer building this component that will MC-338 cargo tanks operate at temperatures below the reliable operating temperature of available design of these tanks is such that access to the inside of the tank to perform repairs to an internal operate reliably at temperatures which may reach minus 452 degrees Fahreneit. Additionally, the valve is not practical. Self closing stop valves are necessary and all MC-338 cargo tanks transporting flammable cryogenic liquids are equipped with these devices, but they are located externally and as external self-closing stop valve as cited in 49 CFR 178.320(a)(8) states that valve: must be designed so close as practical to the tank in accordance with 49 CFR Part 178.338-11(b). The definition of an self-closing valves externally on that the self-stored energy source is located outside the cargo tank and the welded flange. Locating the complying with current requirements does not compromise the safe transportat on of these products. a vacuum insulated tank as close as practical to the tank and 178.338 and This definition further supports the intent of the design and construction requirements in 49 CFR closing stop valve. also enhances and facilitates preventive maintenance and testing of the external self allows for self closing stop valves on MC 338 cargo tanks to be located as close as practical to the Based on this information we are requesting that PHMSA issue an interpretation for 173.33(g) which cargo tank. In addition we recommend that 173.33(g) be changed to read as follows: "(g) Remote control of self-closing stop valves-MC 330, MC 331 and MC 338 cargo tanks. Each liquid or vapor discharge opening in an MC 330 or MC 331 cargo tank must be provided with a remotely controlled internal self-closing stop valve, except when an MC 330 or MC 331 cargo tank is marked certified before January 1, 1995, this requirement is applicable only when an MC 330 or MC 331 cargo and used exclusively to transport carbon dioxide. However, if the cargo tank motor vehicle was tank is used to transport a flammable liquid, flammable gas, hydrogen chloride (refrigerated liquid), or controlled internal or external self-closing stop valve, except when an MC 338 cargo tank is used to Each liquid filling and liquid discharge line in an MC 338 cargo tank must be provided with a remotely transport argon, carbon dioxide, helium, krypton, neon, nitrogen, and xenon. However, if the cargo tank motor vehicle was certified before January 1, 1995, this requirement is applicable only when an MO 338 cargo tank is used to transport flammable ladings." during transit. The second issue that has been identified is that 49 CFR 177.834(i) requires that all valves be closed regulations of 177.837(b), 177.839(b), and 177.841(d). These regulations pertain to Class 3 (flammable This regulation was changed as a result of HM-222B in an effort to consolidate the liquids) materials, Class 8 (corrosive) materials, and division 1 (poison) materials. When these rules were consolidated it was never the intent of the rule to apply to MC-338 cargo tanks. There was no the DOT or industry concerning the effects of this rule change on the Because these external self closing stop valves close with authority, the ability of these valves to close hese valves. Typically ball valves and swing gate valves are used for this application and are equipper vithout leaks may be compromised as a result of frequent cycling (opening, closing, and testing) o ensure the valve closes tightly in an emergency situation. Frequent cycling of these valves exerting this leopardizes he relicauses these valves to une is r, seats, and em packigan co <<>> Page 3 of 3 Based on this information we are requesting that PHMSA issue an interpretation of 49 CFR 177.834(i) ransit. In addition we recommend that 49 CFR 177.834() be changed to read as follows which will permit the external self closing stop valve to remain open on MC-3:38 cargo tanks during (i) Except for a cargo tank conforming to §173.29(b)(2) of this subchapter, a person may not drive a cargo tank motor vehicle containing a hazardous material regardless of quantity unless: (i)(1) All manhole closures are closed and secured; and (j)(2) All valves and other closures in liquid discharge systems are free of leaks; and (i) (3) All valves and other closures in the liquid discharge system must be closed, except the external closing stop valve may remain open during transit for MC-338 cargo tanks. to illustrate the practical application of these safety devices. Enclosed is a video cisc demonstrating the We have provided photos of typical applications of self closing emergency ball and swing gate valves closing force and speed of a ball valve with a spring actuator. The second video fle demonstrates the of our request and if you need any additional information please do not hesitate to contact us at (765- difficulty of resetting the spring actuator and the release mechanism. We appreciate your consideration 564-4684 ext 223) Sincerely Eith Suffer Everett Snoeberger Industry Committee David Hahn Lee Drury Russell Engineering Jack B Kelley Ron Baker 9 Dewar Street 8101 West 34th Avenue Cryogenic Vessel Alternative Dorchester, MA 02125 Amarillo, TX 79121 9528 Warren Avenue 77521 Baytown, TX 77521 Scot Nason Charles Buckley Randy Tumbrello MVE New Prague, MN 56071 407 7th Street Northwest 87 Industrial Ave E. Transgas Logistics Express Lowell, MA 01852 Orange CA 92688 1100 Town and Country Ro Alex Varghese Everett Snoeberger Liegh Valley Industrial Park 9701 SR 25 North Gardener Cryogenics Alloy Custom Products Bethlehem, PA 18020 Lafayette, IN 47905 ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `46245d3b25ac366428300e49bae36c0d49bc33eb899b5aa8b0107edf76ffac0e` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T17:21:50.593Z - Document slug: `phmsa-interpretation-06-0243` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Alloy Custom Products" ], "individuals": [ "Mr. Everett Snoeberger" ], "refIds": [ "06-0243" ], "catalogDates": [ "2007-01-03" ], "catalogParts": [ 173, 177 ], "catalogRowCount": 2, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/50931" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "173.33", "173.33(g)", "177.834", "177.834(j)", "178.338", "173.29(b)(2)", "178.320(a)(8)", "177.837(b)", "177.839(b)", "177.841(d)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/17333", "https://www.phmsa.dot.gov/regulations/title49/section/177834" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2006/060243.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2006/060243.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2006/060243.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/06-0243-18e5e35234.pdf", "pdfArtifactSha256": "76890b10356aeaada35f7f3f73c40bb2427cbd4ae9946ec01b5a963581c24121", "extractedTextPath": "data/sources/phmsa-interpretations/06-0243-18e5e35234.v2.txt", "extractedTextSha256": "874e2f2b675f97191a71316882d6e161dfb039b2400bb9bcbedd3ec81e82e4a5", "pageCount": 5, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```