1501 Midpark Road
Knoxville, Tennessee 37921
Dear Mr. Bishop:
This responds to your letter asking about Standard No. 208's requirements for pressure vessels that are continuously pressurized. Section S9.1 of the standard incorporates certain provisions of the Hazardous Materials Regulations issued by DOT's Research and Special Programs Administration (RSPA). You noted that you have recently received an exemption from RSPA concerning one of those provisions, 49 CFR 178.65- 11(a). Under RSPA's regulation, you must conduct a pressure test on each cylinder before it is shipped, including holding a specified pressure for 30 seconds. Under the exemption, the hold time for testing each cylinder may be limited to "that which is adequate to show compliance." You asked whether compliance with the provisions of the exemption "satisfies the intent of paragraph S9.1, FMVSS 208."
The answer to your question is that an exemption from RSPA does not change your responsibility under Standard No. 208. However, as discussed below, Standard No. 208 does not incorporate all of the provisions of 49 CFR 178.65-11(a). In particular, Standard No. 208 does not require you to test each cylinder but instead requires you to assure that each cylinder, if tested in accordance with 49 CFR 178.65-11(a), including the 30 second hold time, would meet the specified performance requirements.
The National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, it is the responsibility of the manufacturer to certify that its vehicles or equipment comply with applicable safety standards.
Section 9.1 of Standard No. 208 states:
A pressure vessel that is continuously pressurized . . . shall not leak or evidence visible distortion when tested in accordance with ' 178.65-11(a) of this title and shall not fail in any of the ways enumerated in ' 178.65-11(b) of this title when hydrostatically tested to destruction.
You noted in your letter that 49 CFR 178.65-11(a) specifies, among other things, that "each cylinder must be tested at an internal pressure of at least the test pressure and must be held at that pressure for at least 30 seconds." Under RSPA's regulation, you must conduct the pressure test on each cylinder before it is shipped, including holding a specified pressure for 30 seconds. However, paragraph 7b(1) of the exemption RSPA granted you (DOT-E 11494) provides that "the hold time at test pressure . . . may be limited to that which is adequate to ensure compliance."
Your letter raises two issues. The first is whether NHTSA requires each cylinder to be tested. The second is whether a 30 second hold time is required to satisfy Standard 208.
Unlike RSPA=s requirements, NHTSA does not require each cylinder to be tested. The RSPA requirement to test each cylinder before it is shipped is a quality control provision. When NHTSA added the requirements for pressure vessels to Standard No. 208 (see May 6, 1972 final rule (37 FR 9222), copy enclosed), the agency adopted some, but not all of RSPA's Specification 39 (49 CFR 178.65). Notably, the "quality control" requirements of RSPA were not adopted. NHTSA stated:
A continuously pressurized vessel is required to conform to the requirements of Specification 39 concerning type, size, service pressure, and test pressure of vessels (paragraph 2 of the specification); seams (6(b)); wall thickness (7); openings and attachments (9 (a) and (b)); safety devices (10); pressure tests (11); and flattening tests (12). The reference to the latter two paragraphs are drafted to make it clear that the quality control aspects of those paragraphs are not included in the standard. The remaining portions of Specification 39 . . . are not incorporated. [Emphasis added.]
Thus, while Standard No. 208 incorporated the pressure test performance requirements of that paragraph, it did not adopt the quality control provisions. There is no requirement in the standard that each cylinder must be pressure tested. However, as explained more below, you are responsible for assuring the compliance of each cylinder with the specified performance requirements.
30-Second Hold Time.
Although the RSPA exemption permits you to test your cylinders for less than 30 seconds, an exemption from RSPA does not change your responsibility under Standard No. 208. Under Standard No. 208, you are responsible for assuring that each cylinder, if tested in accordance with 49 CFR 178.65-11(a), including the 30 second specification, would not leak or evidence visible distortion. However, nothing in Standard No. 208 requires you to test each cylinder or to test for a 30 second minimum. You may be able to provide such assurance by a variety of means, included, but not limited to, engineering analyses, computer simulations, testing each cylinder, sample testing, or a combination of these activities.
While your exemption from RSPA does not change your responsibility under Standard No. 208, you may be able to use the testing you conduct to meet RSPA responsibilities to also meet your Standard No. 208 responsibility. That is, you may be able to base your certification of compliance with Standard No. 208 on the data you already have.
If you have any other questions, please feel free to contact Edward Glancy of my staff at this address or by phone at (202) 366-2992.
Samuel J. Dubbin Chief Counsel
Enclosure ref:208 d:5/9/96