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Interpretation Response #09-0306 ([Hazmat Resources, Inc.] [Mr. Danny Shelton])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Hazmat Resources, Inc.

Individual Name: Mr. Danny Shelton

Location State: NC Country: US

View the Interpretation Document

Response text:

November 9, 2010



Mr. Danny Shelton

Hazmat Resources, Inc.

10104 Creedmoor Road

Raleigh, NC 27615

Ref. No. 09-0306

Dear Mr. Shelton,

This responds to your letter dated December 15, 2009 requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to cargo tanks. Specifically, you describe three scenarios and ask several specific questions for each scenario. The scenarios and questions are paraphrased and answered as follows:

Scenario 1

A motor carrier offers an MC 331 cargo tank motor vehicle to a facility and requests that it perform the required annual tests.

Q1) Is the CT facility required to open the tank and inspect the inside of the cargo tank for evidence that the tank has transported lading corrosive to the tank?

A1) No. The CT facility may rely on information provided by the owner/user of the cargo tank to determine if the cargo tank was used to transport material corrosive to the tank. However, the CT facility may elect to perform examinations or tests to determine if the tank transported materials that are corrosive to the tank and/or valves.

Q2) If a motor carrier advised a CT facility that its tank (MC 331 NQT cargo tank motor vehicle constructed of SA 612 material) was used to transport compressed gas that contained hydrogen sulfide, would an internal inspection be required annually and would a thickness test be required every two years?

A2) Yes. The phrase "corrosive to the tank or valve" means that the lading has been shown through experience or test data to reduce the thickness of the material of construction of the tank wall or valve (see § 180.403). Experience and test data have shown that hydrogen sulfide is corrosive to carbon steel.

Q3) If a product causes stress corrosion cracking on the cargo tank wall is that considered corrosive to the tank? If the answer is "yes," does that mean that an internal inspection is required annually and thickness testing is required every two years?

A3) Yes, stress corrosion cracking on the cargo tank wall is considered a condition that results from material that is corrosive to the tank. All tests and inspections for cargo tanks that transport materials "corrosive to the tank" must be performed in accordance with the schedule specified in Part 180.

Scenario 2

A motor carrier offers a DOT 407 unlined cargo tank constructed of 316L Stainless to a CT facility for an annual inspection. The tank was cleaned and purged and all placards were removed before transporting the tank to the facility and it has been determined this tank transports a material that is classified as a corrosive material.

Q1) If a material is classed as a Class 8 (Corrosive) material, does this mean the material is corrosive to the material of construction of the cargo tank wall and the material of construction of the valve?

A1) No. The phrase "corrosive to the tank" is explicitly defined in § 180.403 and is not related to the definition of a Class 8 (Corrosive) material in § 173.136.

Q2) Who is responsible for making the determination that the cargo tank was transporting a material that was corrosive to the tank or valve?

A2) It is the owner and/or user"s responsibility to ensure that the cargo tank is periodically tested and inspected in accordance with Part 180. Thus, it is the responsibility of the owner and/or user to determine if the cargo tank transports material corrosive to the tank for the purpose of testing and inspection.

Q3) What tests are required to be performed to confirm the tank was transporting a material corrosive to the tank or valve? If the cargo tank was designed to transport corrosive material without a liner, is that sufficient to make the determination that the material is not corrosive to the cargo tank wall or valve?

A3) The HMR do not require the performance of specific tests to confirm that a cargo tank has transported a material corrosive to the tank or valve. The fact that a cargo tank was designed to be used without a liner does not provide enough information to conclusively determine whether the tank has been used to transport material corrosive to the tank as defined by the HMR.

Scenario 3

A welded repair is performed on a cargo tank. Section 180.413(b) states "The suitability of each repair affecting the structural integrity or lading retention capability of the cargo tank must be determined by the testing required either in the applicable manufacturing specification or in § 180.407(g)(1)(iv). Each repair of a cargo tank involving welding on the shell or head must be certified by a Registered Inspector."

Q1) What is meant by the phrase "certified by a Registered Inspector" in § 180.413(b)?

A1) The phrase "certified by a Registered Inspector" in § 180.413(b) means that a Registered Inspector has verified the suitability of the repairs and has determined that the repaired cargo tank meets the prescribed specification through testing required in either the applicable manufacturing specification or in § 180.407(g)(1)(iv) and has stated his findings in writing.

Q2) What training must a Registered Inspector have in order to certify a welded repair on a cargo tank?

A2) A Registered Inspector who certifies a welded repair on a cargo tank must meet the minimum qualifications for inspectors and testers in § 180.409 and the knowledge and ability requirements in the definition of a Registered Inspector (see definition in § 171.8).

Q3) What information must be included on the certification?

A3) A test and inspection report must include the information specified in § 180.417(b) and/or (c), as appropriate, including the location of defects found; method of repair; and dated signatures of both the Registered Inspector and the cargo tank owner.

Q4) How long must these certification documents be maintained and who is required to maintain these certification documents?

A4) Each owner of a cargo tank motor vehicle must retain at the owner's principal place of business all records of repair, modification, stretching, or rebarrelling, including notation of any tests conducted to verify the suitability of the repair, modification, stretching or rebarreling made to each cargo tank during the time the cargo tank motor vehicle is in service and for one year thereafter. Copies of these records must be retained by a motor carrier, if not the owner of the cargo tank motor vehicle, at its principal place of business during the period the cargo tank motor vehicle is in the carrier's service.

Q5) Under the HMR, the testing may be in accordance with either the applicable manufacturing specification or § 180.407(g)(1)(iv). Does this mean that one can test the repair of an MC 331 QT tank at 2 times the design pressure as required by § 178.337-16(a)?

A5) Yes. Testing an MC 331(QT) cargo tank at 2 times the design pressure is in accordance with the manufacturing specification.

Q6) If the answer to Q5 is "yes," and if a person tests the repair on an MC 331 QT tank with a MAWP of 265 psi at 530 psi, is this procedure a violation of §§ 180.407(a)(2) and 180.407(g)(1)(iv)?

A6) No. The regulations offer the option of either performing the test in accordance with the applicable manufacturing specification or § 180.407(g)(1)(iv). Section 180.407(a)(2) is not relevant to the question since testing the repair requires a pressure test.

I hope this information is helpful. If you have further questions, please contact this Office.


Ben Supko

Acting Chief, Standards Development

Office of Hazardous Materials Standards

180.403, 173.136, 180.413, 180.417(b)&(c), 180.407

Regulation Sections

Section Subject
173.136 Class 8-Definitions
180.403 Definitions
180.407 Requirements for test and inspection of specification cargo tanks
180.413 Repair, modification, stretching, rebarrelling, or mounting of specification cargo tanks