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Accident Report Detail

Rupture of a DOT-105 Rail Tank Car and Subsequent Chlorine Release at Axiall Corporation

Executive Summary

​On August 27, 2016, about 8:26 a.m. eastern daylight time, a railroad tank car sustained a 42-inch long crack in its tank shell shortly after being loaded with 178,400 pounds of liquefied compressed chlorine at the Axiall Corporation Natrium plant in New Martinsville, West Virginia. Over the next 2.5 hours, the entire 178,400-pound load of chlorine was released and formed a large vapor cloud that migrated south along the Ohio River valley. The railroad tank car, AXLX1702, built in June 1979 by ACF Industries, Incorporated, was a 17,388-gallon US Department of Transportation specification-105J500W tank car, also known as a class DOT-105 tank car, with a stenciled load limit of 178,400 pounds and a maximum gross rail load of 263,000 pounds.

Probable Cause

​The National Transportation Safety Board determines that the probable cause of the chlorine release was an undetected preexisting crack near the inboard end of the stub sill cradle pad, that propagated to failure with the changing tank shell stresses during the thermal equalization of the car after loading with low temperature chlorine. Contributing to the failure was Axiall Corporation’s insufficiently frequent stub sill inspection interval that did not detect the crack, the low fracture resistance of the nonnormalized steel used in the tank car construction, and the presence of residual stresses associated with Rescar Companies’ tank wall corrosion repairs and uncontrolled local postweld heat treatment.

Accident Location: New Martinsville , WV USA  
Accident Date: 8/27/2016
Accident ID: DCA16SH002

Date Adopted: 2/11/2019
NTSB Number: HZM1901
NTIS Number: PB2019-100294