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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #12-0176 ([Georgia Fire Protection] [Mr. W.A. Andrews])

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

Interpretation Response Details

Response Publish Date:

Company Name: Georgia Fire Protection

Individual Name: Mr. W.A. Andrews

Location State: GA Country: US

View the Interpretation Document

Response text:

This responds to your July 30, 2012 letter and September 11, 2012 email requesting further clarification of your May 25, 2012 letter of clarification under Ref. No. 12-0129 on requalification of cylinders under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you request clarification of when a cylinder may be retested under § 180.205(g)(5) due to equipment failure that results in a failed outcome. In your email and May 25 letter, you describe two types of failure scenarios that led to your request: 1) during a test of a 3AA cylinder, the test equipment failed to transfer volume from the jacket to the weight indicating device leading to the device showing minimal or no increase in weight, which results in either an aborted test or a failure at 100% expansion; and 2) during a test of a 3AL cylinder, the test adapter to the cylinder had an O-ring failure resulting in a greater than 10% permanent expansion reading. During both of these scenarios your technician became aware of the test equipment failure that you believe accounted for an erroneous permanent expansion reading.

You explain further that your company uses computerized test equipment that performs and records the test and results. Moreover, you provide information from the manufacturer of this equipment that corroborates your conclusion of equipment failure. Finally, you also provide the cylinder test result reports associated with these scenarios for our reference.

In accordance with § 180.205(g)(3) of the HMR, the retester must confirm test equipment is properly functioning before the onset of any retesting. This accuracy check of the testing system, as well as adherence to any manufacturer maintenance recommendations, is designed to make a retester aware of any testing system problem(s) prior to the onset of pressure testing. Also, in accordance with § 180.205(g)(5), a retester may perform a system check at or below 90% of the test pressure prior to a retest to look at the testing system and cylinder for any leaks. However, we understand that test equipment can and will occasionally fail during performance of a cylinder pressure test. Your questions are paraphrased and answered as follows:

Q1. Does § 180.205(i)(1)(iv) require condemnation of the 3AA cylinder in scenario 1 or does the test equipment failure invalidate the first attempt results and allow a retest under § 180.205(g)(5)?

A1. As previously stated in our response under Ref. No. 12-0129, in the case of a malfunction of the test equipment during a full retest (above 90% of the test pressure), performance of a repeat test is authorized in accordance with § 180.205(g)(5). However, a cylinder required to be condemned under § 180.205(i) is not authorized for retesting. Section 180.205(i)(1)(iv) refers to condemnation of a DOT specification cylinder experiencing permanent expansion exceeding 10% of total expansion under proper test conditions. The cylinder does not have to be condemned if it can be substantiated that the test equipment failure led to a false reading. Note that the reason for this repeat test must be included on the test record in accordance with § 180.215(b)(2). The repeat test must be performed at a pressure increased by 10% or 100 psig, whichever is less. Because of the unique circumstance of the equipment malfunction, we recommend recalibrating the test equipment before conducting the repeat test. Also, we recommend performance of a system check at or below 90% of test pressure prior to the repeat test to ensure the system is functioning properly. Finally, we caution that at no time should a cylinder retest exceed 110% of the minimum test pressure. If a cylinder is pressurized to more than 110% of the minimum test pressure, it may cause embrittlement of the cylinder"s sidewall which could result in failure of the cylinder in service.

Q2. Does § 180.205(i)(1)(iv) require the condemnation of the 3AL cylinder in scenario 2 or does the test equipment failure invalidate the first attempt results and allow a retest under § 180.205(g)(5)?

A2. See A1.

I hope this answers your inquiry and clarifies our previous response. If you need additional assistance, please contact this office at (202) 366-8553.


Robert Benedict
Chief, Standards Development Branch
Standards and Rulemaking Division


Regulation Sections

Section Subject
180.205 General requirements for requalification of specification cylinders