By Patrick Rucker
WASHINGTON (Reuters) - Federal investigators will examine whether pressurized gas played a role in the massive blast that followed the derailment of a train carrying crude oil through West Virginia this week, the U.S. Transportation Department said on Thursday.
Questioning the possible role of gas vapors in the West Virginia fire broadens the debate over how to ensure public safety at a time when drastically larger volumes of crude oil are being shipped by rail and roll through cities and towns.
At least two dozen oil tankers jumped a CSX Corp track about 30 miles south of the state capital, Charleston, on Monday, touching off a fireball that sent flames hundreds of feet into the sky.
The U.S. Transportation Department said it has an investigator at the site to take samples of crude once the wreckage stops burning.
"We will measure vapor pressure in the tank cars that derailed in West Virginia," said department spokeswoman Suzanne Emmerling.
Some experts say the nature of the explosion, which saw a dense cloud of smoke and flame soaring upwards, could be explained by the presence of highly pressurized gas trapped in crude oil moving in the rail cars.
"Vapor pressure could be a factor," said Andre Lemieux of the Canadian Crude Quality Technical Association, a trade group which is helping the Canadian government adopt crude oil quality tests.
The American Petroleum Institute, the leading voice for the oil industry, declined to comment on whether high vapor pressure might have played a role in West Virginia.
"What we need to do now is allow the accident investigators to do their jobs," said Brian Straessle, a spokesman for the trade group.
In the past twelve months, API and the North Dakota Petroleum Council have argued that the dangers of vapor pressure are exaggerated, citing self-funded studies that indicate vapor pressure readings are safe.
The Transportation Department did not call for regulations governing the presence of gas vapors in a national oil train safety plan it drafted last summer and is now with the White House for review.
That plan would have oil trains fitted with advanced braking systems to prevent pileups and tougher shells akin to those carrying volatile propane gas on the tracks.
The question of whether gas vapors make oil shipments more prone to detonate has been kept on the margins of the U.S. debate over transporting oil by rail.
The oil train sector has thrived in recent years, pushed by a crude oil renaissance in North Dakota's Bakken region.
(Reporting By Patrick Rucker; Ernest Scheyder contributed from Williston, North Dakota; editing by Andrew Hay)