Trinity Industries, Inc. — Hazardous Materials Safety Interpretation

Page 1of Transportation U.S. Department AUG 29 2007 Washington, D.C. 20590 400 Seventh Street, S.W. peline an Administration azardous Materials Safe Mr. Greg McRae Ref. No. 06-0020 Engineering and Technical Director Trinity Industries, Inc. P.O. Box 56887 2525 Stemmons Freeway Dallas, TX 75356 Dear Mr. McRae: This responds to your letter regarding the repair of MC 331 cargo tanks under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). I apologize for the delay in responding and for any inconvenience it may have caused. Specifically, you inquire whether a dye penetrant examination is an acceptable alternative to a radiographed examination. Your questions are paraphrased and answered below. Q1. Is a dye penetrant (liquid penetrant, PT) examination of a welded joint containing a backing bar in the shell or alternative to Radiographic (RT) examination of a full hemispherical head of an MC 331 cargo tank an acceptable penetration weld? A1. NO. The basis for this determination is the original construction requirements for an MC 331 cargo tank under construction and certification of an MC 331 cargo tank be $ 178.337-1. This section mandates that the design, in accordance with the ASME Code which in turn requires Section VIII, Div 1, radiographic examination of this type of weld. See ASME Part UW-11; UW-12: Table UW-12. Further, because this action is considered a repair, the requirements for such a repair are mandated by § 180.413 and the National Board Inspection Code (NBIC) . performed in accordance with the original code of See NBIC RC 1090 and RD 2060. NBIC requires welding to be received construction, that is, if the original pressure vessel an RT examination, the repaired pressure vessel would also need an RT examination. Any deviation from this 180.407 060020#

Page 2requirement would be subject to the approval of the which allows for welding methods as alternatives to post- Inspector. Additional guidance is provided in RD 1020, weld heat treatment. In addition, this guidance specifies that if it is not practical to RT the weld, a successful (defect free) PT examination must be conducted and the maximum allowable working pressure (MAWP) of the pressure vessel must be re-evaluated by the jurisdiction. Q2. If a repaired MC 331 cargo tank was fully radiographed when originally constructed and the repair weld is not based on lower joint efficiency? radiographed, should the MAWP of the cargo tank be reduced A2. parties involved. Yes, provided prior agreement is obtained from all See reasoning in Al above. we cam be of further assistance. I trust this satisfies your inquiry. Please contact us if Sincere Hattie L. Mitchell Office of Hazardous Materials Standards Chief, Regulatory Review and Reinvention 180.407#

Page 3Stevens § 180.407 Cargo Tank TRINITY INDUSTRIES, INC. 06 - 0020 January 26th , 2006 Research and Special Programs Administrator Office of Hazardous Material Safety Attn: DHM-10, 400 7th Street SW U.S. Department of Transportation Washington, DC 20509-0001 Re: Title 49 CFR, Part 180. 407 Request for Interpretation When making internal repairs to an MC-331 Cargo Tank constructed without a Background: opening, in either, the shell or hemispherical head. After internal repairs are manway, the process for making such repairs involves cutting an access completed a backing bar is welded to the inside the cargo tank and the access opening plate welded in place, followed by dye penetrant examination of the weld. Question 1: Is Dye Penetrant examination of the weld surface an acceptable alternative for Radiographic examination inspection of a full penetration weld? If, in the original cargo tank design and construction, the cargo tank is fully Question 2: radiographed and stamped in accordance with ASME code requirements, should a non radiographed repair weld cause the MAWP to be reduced accordingly for a cargo tank with a lower joint efficiency. Respectively, Greg McRae Engineering and Technical Director Trinity Industries Inc. 2525 Stemmons Freeway, Dallas Tx. 75356 P.O. Box 568887 75356-8887#