Polar Service Centers — Hazardous Materials Safety Interpretation

Page 1US. Department of Transportation 400 Seventh Streel, S.W. Research and Washington, D.C. 20590 special Programs Administration JUL 21999 Mi. Mark Hughes Polar Service Centers Ref. No. 98-0286 120 Cedar Springs Road Spartansburg, SC 29302 Dear Mr. Hughes: This is in response to your letter dated September 21, 1998, and further clarifies our letter of September 4, 1998, MC 307 cargo tanks under the Hazardous Materials Regulations regarding a suitable corrosion allowance for sulfuric acid in (HMR; 49 CFR Parts 171-180). a certain unlined 316 SS MC 307 cargo tank approved for Specifically, you asked whether sulfuric acid in all concentrations meets the allowance specified in special provision B84 (S 172.102). concentrations up to 65.25% and does not apply to Special provision B84 applies only to sulfuric acid in metallic lining or a suitable corrosion allowance as stated in concentrations greater than 65.25%. The requirements for non- special provision B84 do not apply to sulfuric acid in concentrations above 65.25% In reference 'assumed that the original" design minimum thickness was not to the September 4, 1998 letter we sent you, we greater, than 3/16". minimum, thackness, and the designer's corrosion allowance The cargo tank designer's calculated should be used to determine whether or not the remaining corrosion allowance is suitable. i* I hope this satisfiesiyour request. Sincerely, Delmer F. BiLlings Chief, Standards Development Office of Hazardous Materials Standards 172.102 980286#