Baker Petrolite Corporation — Hazardous Materials Safety Interpretation

Page 11200 New Jersey Ave., SE u.s. Department Washington, DC 20590 of Transportation Pipeline and Hazardous Materials Safety Administration NOV 6 2009 Mr. Aubrey R. Campbell Baker Petrolite Corporation 12645 West Airport Blvd. P.O. Box 5050 Sugarland, TX 77478-5050 Ref. No. 09-0229 Dear Mr. Campbell: This responds to your October 2, 2009 letter requesting clarification of the requirements under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) for the transportation of cryogenic liquids in tank cars. Specifically, you request clarification concerning whether the pressure test requirements for class DOT 113 tank cars under § 173.319( e) apply to tank cars containing the residue of a cryogenic liquid. According to your letter, your company offloads refrigerated liquid ethylene from DOT 113 tank cars to a minimal amount considered to be empty by industry standards. The empty tank cars containing a residue ofrefrigerated liquid ethylene are then returned to the supplier. Based on its understanding ofthe requirements for empty packagings in § 173.29, which requires an empty packaging containing only the residue ofa hazardous material to be transported in the same manner as when it previously contained a greater quantity of hazardous material, the supplier, in accordance with § 173.319( e), monitors the average daily pressure rise in the empty tank cars and conducts follow-up thermal integrity testing on the empty tank cars ifthe average daily pressure rise exceeds 3 psig (0.2 Bar). You ask if the requirements in § 173.319( e) apply to a tank car that is empty except for a residue of the hazardous material it previously contained. The answer is no. DOT 113 tank cars containing the residue of a cryogenic liquid are not subject to the requirements of § 173.319( e). Monitoring ofthe average daily pressure is used to gauge whether energy is being transferred to the lading through the insulation ofthe tank car, thus indicating a potential problem with the insulation and the need for follow-up thermal integrity testing. Monitoring of DOT 113 tank cars containing residue amounts is not effective for this purpose because the same amount of energy input will cause a greater increase in temperature and vaporization of a small amount of liquid than a large amount of#

Page 2I : ! ! I I I liquid. The resulting increase in pressure in a tank car containing a residue does not provide I an accurate indication of potential insulation problems. I I I hope this information is helpful. If you have further questions, please contact this office. I Si:r~ harles E. Betts hief, Standards Development ce of Hazardous Materials Standards#

Page 3~ ,'" ; . .' " De-r- 16 vn-deref1 ....~ ,-' ...... • 1; f" ·t f .~." , • Office ofHazardous Materials Standards ~ (13-2'1 Pipeline and Hazardous Materials Safety Administration, (PHMSA) q J 13· "31 cr Attn: PHH-10 . . .' U.S. Department of Transportation EII1~fj Pud([~jinjS East Building, 1200 New Jersey Avenue, SE Washington, DC 20590-0001.. 09-0h:Lq Re: Letter of Interpretation Dear Office ofHazardous Materials Standards: Baker Petrolite Corporation (BPC) requests a letter, of interpretation regarding the provisions specified in Title 49 Code of Federal Regulation(CFR) Part 173.29(a)~ Empty Packages, Part 173.319(a)(4)(iii), 173.319(b)(2), and 173.319(e)(l)(2), Cryogenic liquids in tank cars. BPC supplier Equistar offers for transportation by rail a hazardous materials described as UN1038, Ethylene, refrigerated liquid, 2.1, in DOT 113 tank cars. BPC owns and operates the rail cars; and is responsible to monitor each shipment to ensure the average daily pressure rise in the loaded tank car does not exceed 0.2 Bar (3 psig) during the loaded run or in a 24 hour period. Additionally, the supplier's loading procedure ensures the microns are at or below 75 microns of mercury' and the pressure reduced to less than 10 psig before the tank car is released in interchange. Therefore, we iterate that we experience no problems transporting this material in loaded tank cars. At destination, BPC offloads the Ethylene to a minimal amount, which is considered "empty" or "residue last contained" by industry standards. Furthermore, BPC procedure is to reduce the pressure in the empty tank cars to'less than 5 psig and most often to zero prior to offering the empty tank car for interchange back to the supplier. According to 173.29(a), except as otherwise provided in this section, an empty package containing only the residue of a hazardous materials shall be offered for transportation and transported in the same manner as when it previously contained a greater quantity ofthat hazardous material. Based on this requirement, the supplier makes available to BPC the average daily pressure rise on the returning empty cars with the readings occasionally exceeding 3 psig. Additionally, the supplier making the information available to BPC conducts a micron test on the empty tank cars and reports to BPC when the reading exceeds 75 microns ofmercury.#