Interpretation Response #15-0117
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
June 8, 2016
Investigator JI-hoon Chang
Intellectual Criminal Investigation Squad
Korea National Police
Reference No. 15-0117
Dear Mr. Chang:
This letter is a follow-up to a response you received from the Pipeline and Hazardous Materials Safety Administration (PHMSA; Reference Number 15-0089) on May 13, 2015 and to your June 16, 2015 email inquiry and subsequent correspondence with an Investigator of PHMSA's Field Operations Division requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to Department of Transportation (DOT) Specification 3AAX seamless steel cylinders. Your questions pertain to the specific operations of a company, NK Company LTD, and have been paraphrased and answered as follows:
A1. The answer is yes, adding thickness around the neck of a DOT-3AAX seamless steel cylinder is considered welding or brazing. Please be advised that as specified in § 178.37(e) of the HMR, welding or brazing for any purpose whatsoever is prohibited except for: (1) the attachment of neckrings and footrings which are non-pressure parts, and only to the tops and bottoms of cylinders having a service pressure of 500 psig or less; and (2) as permitted in paragraph (d) (Manufacture) of § 178.37. The neck of a cylinder is considered a pressure part.
Q2. What criteria are used to determine whether a cylinder neckring or footring is a "pressure part" or a "non-pressure part" for the purposes of § 178.37(e)(1)?
A2. Neckrings and footrings are non-pressure parts. For the purposes of § 178.37(e)(1), a neckring or footring can only be attached by welding to the top or bottom exterior of a cylinder with a service pressure of 500 psig or less. For the purposes of § 178.37(e)(1), any portion of the cylinder itself is considered a pressure part.
Q3. Is PHMSA aware of any instances of failure as a result of welding around the neck of a DOT specification 3AAX cylinder?
A3. No, we are not aware of any instances of failure as a result of welding around the neck of a DOT specification 3AAX cylinder.
Q4. For the purposes of § 178.37(d) (Manufacture), does the phrase "...the surface may be machined or otherwise treated to eliminate these defects." include welding?
A4. No, it does not include welding to eliminate a defect. For the purposes of § 178.37(d), welding refers to an end closure in the finished cylinder that is welded by spinning in the manufacturing process.
Q5. Are there similar issues with welding on other DOT cylinder specifications?
A5. The answer is yes. Each DOT cylinder specification's welding procedures are prescribed in Subpart C of Part 178. None of those specifications authorize welding to correct defects in the pre- or post-manufacturing process. This requirement is necessary to prevent a cylinder from rupturing, resulting in extensive property damage, serious injury, or death.
I hope this information is helpful. Please contact us if we can be of further assistance.
T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division
178.37(e)(1), 178.37(d), 178.37
|§ 178.37||Specification 3AA and 3AAX seamless steel cylinders|