Hazardous Materials Accident Summary Report - Failure of Tank Car TEAX 3417 and Subsequent Release of Liquefied Petroleum Gas

Pasadena, Texas
November 22, 1997

NTSB Number: HZM-98-01-SUM
NTIS Number: PB98-917007
Adopted December 1, 1998
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Executive Summary

On November 22, 1997, a frost ring that signified product leakage was discovered on the bottom center of a tank car that was being unloaded at the Georgia Gulf Corporation chemical plant in Pasadena, Texas. The tank car contained 29,054 gallons of a propylene/propane mixture, a liquefied flammable gas. The tank car had been purged with cryogenic nitrogen on October 17, about a month before the accident. No injuries or fatalities were reported as a result of the failure of the tank car. Georgia Gulf estimated that approximately 52 gallons of the cargo were released. Total damage, including the cost of the clean up, loss of product, and repair of the tank car, was estimated to be slightly less than $9,300.

Probable Cause

The National Transportation Safety Board determines that the probable cause of the thermal shock failure and the subsequent leakage of product from tank car TEAX 3417 was the failure of Bayou Railcar Services, Inc., to utilize sufficient safeguards to ensure that the nitrogen was properly warmed before it was injected into the tank car during nitrogen purging.

The safety issues discussed in this report are the need to safeguard tank cars adequately when they are being purged with nitrogen and the use of engineering analyses of the properties of tank car steels in the development of industry-recommended procedures for the purging of tank cars with nitrogen.

As a result of its investigation, the National Transportation Safety Board issued recommendations to the Compressed Gas Association, Inc., the Federal Railroad Administration, and the Association of American Railroads.

Recommendations

As a result of this accident, the National Transportation Safety Board makes the following safety recommendations:

To the Compressed Gas Association, Inc.:

In cooperation with the Federal Railroad Administration and the Association of American Railroads, revise its Recommended Procedures for Nitrogen Purging of Tank Cars to specify a minimum threshold temperature for nitrogen that is based on an engineering analysis of ductile-to-brittle transition temperatures of tank car steels. (R-98-70)

To the Federal Railroad Administration:

Cooperate with the Compressed Gas Association, Inc., in its efforts to revise its Recommended Procedures for Nitrogen Purging of Tank Cars to specify a minimum threshold temperature for nitrogen that is based on an engineering analysis of ductile-to-brittle transition temperatures of tank car steels. (R-98-71)

To the Association of American Railroads:

Cooperate with the Compressed Gas Association, Inc., in its efforts to revise its Recommended Procedures for Nitrogen Purging of Tank Cars to specify a minimum threshold temperature for nitrogen that is based on an engineering analysis of ductile-to-brittle transition temperatures of tank car steels. (R-98-72)