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Interpretation Response #09-0229 ([Baker Petrolite Corporation] [Mr. Aubrey R. Campbell])

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

Interpretation Response Details

Response Publish Date:

Company Name: Baker Petrolite Corporation

Individual Name: Mr. Aubrey R. Campbell

Location State: TX Country: US

View the Interpretation Document

Response text:

November 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 of refrigerated liquid ethylene are then returned to the supplier. Based on its understanding of the requirements for empty packagings in § 173.29, which requires an empty packaging containing only the residue of a 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 if the 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 of the average daily pressure is used to gauge whether energy is being transferred to the lading through the insulation of the 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

liquid. The resulting increase in pressure in a tank car containing a residue does not provide an accurate indication of potential insulation problems.

I hope this information is helpful. If you have further questions, please contact this office.


Charles E. Betts

Chief, Standards Development

Office of Hazardous Materials Standards

173.319(e) 173.29

Regulation Sections

Section Subject
173.29 Empty packagings
173.319 Cryogenic liquids in tank cars