Interpretation Response #99-0136 ([RNG Pro-Tech, Inc.] [Mr. Don Nelson])
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: RNG Pro-Tech, Inc.
Individual Name: Mr. Don Nelson
Country: CA
View the Interpretation Document
Response text:
February 2, 2000
Mr. Don Nelson Ref. No. 99-0136
Quality Assurance Manager
RNG Pro-Tech, Inc.
1026 Western Drive
P.O. Box 830
Crossfield, Alberta
TOM OSO Canada
Dear Mr. Nelson:
This is in response to your letter dated May 27, 1999, concerning the factor of safety (FS) in the design of DOT specification cargo tank motor vehicles under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you inquire whether the FS reduction from 4:1 to 3.5:1, as authorized in the 1999 Addenda of the 1998 ASME Code, is permissible under the HMR.
The answer is no. The structural integrity requirements provided in § 178.337-3 allow for the maximum stress value prescribed in Section VIII of the ASME Code or 25 percent of the tensile strength of the material used. The HMR currently incorporate by reference the 1992 edition of the ASME Code with addenda through December 31, 1993, which mandates an FS of 4:1.
In a recently published notice of proposed rulemaking (Docket No. HM-218; 64 FR 53165; September 30, 1999), we proposed to incorporate by reference the 1998 edition of the ASME Code for Section VIII, Division I, without the 1999 addenda. This proposal will maintain the currently authorized FS of 4:1. Any deviation from this prescribed FS for a DOT specification cargo tank motor vehicle must be approved under the terms of a DOT exemption.
I trust this satisfies your inquiry. Please contact us if we can be of further assistance.
Sincerely,
Hattie L. Mitchell
Chief, Regulatory Review and Reinvention
Office of Hazardous Materials Standards
178.345