Interpretation Response #07-0031 ([West-Mark] [Mr. Gary Spoelstra])

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

Interpretation Response Details

Response Publish Date: 04/29/2008

Company Name: West-Mark

Individual Name: Mr. Gary Spoelstra

Location State: CA Country: US

View the Interpretation Document

Response text:

April 29, 2008

Mr. Gary Spoelstra

Chief Engineer

West-Mark

P.O. Box 100

Ceres, California 95307

Ref. No.: 07-0031

Dear Mr. Spoelstra:

This is in response to your January 10, 2007 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to cargo tanks. Your questions are based on an interpretation issued in 1993, in which we specified that DOT 400 series tanks could be designed without considering weld efficiencies less than 100% and still meet the requirements in the HMR. You state that Section XII of the ASME Code, which we will be incorporating into the HMR, will invalidate the 1993 interpretation by mandating the use of full design stress at 70% joint efficiency on a large population of tanks. The result of this would generate heavier tanks, a situation not in keeping with the present regulations if not properly addressed. Specifically, you ask for us to allow a 20% increase in allowable compressive and tensile stress for longitudinal bending in cargo tanks when considering the extreme case of .7G as specified in § 178.337 3(c)(2)(iii)(C) for MC 331 cargo tanks and paragraphs (c)(2)(iii)(C) and (c)(2)(iv)(B) of § 178.345 3 for DOT 400 series cargo tanks.

Based on the information provided, we have determined that it is acceptable to use the long standing ASME Section VIII criteria in UG-23(d) of a 20% increase in allowable stress for certain conditions. For DOT 400 series cargo tanks, the allowable compressive and tensile stress may be increased 20% when analyzing longitudinal bending in cargo tanks when considering the extreme load case of .7G as specified in § 178.345 3 (c)(2)(iii)(C) and (c)(2)(iv)(B). We will be addressing this issue in a future rulemaking.

Please note that although ASME UG-23(d) may be an appropriate alternative criterion to use in the analysis of certain loading conditions for other cargo tank specifications, we are limiting your request to that which is directly related to the co-operative research effort

between DOT and industry for 400 series cargo tanks and the supporting documentation provided in your letter.

I hope this information is helpful. If you have further questions, please do not hesitate to contact this office.

Sincerely,

Hattie L. Mitchell

Chief, Regulatory Review and Reinvention

Office of Hazardous Materials Standards

178.345-3(c)(2)(iii)

Regulation Sections