The crude oil aboard the Montreal, Maine & Atlantic Railway train that derailed and exploded July 6 in a small town in Quebec was mislabeled and more explosive than previously thought, Canadian officials said Wednesday.

Officials with the Transportation Safety Board of Canada said their discovery of the error – on a document intended to help railroad workers properly handle dangerous cargo – helps explain why the derailment caused so much damage.

The investigators said any errors ultimately are the responsibility of the oil’s buyer and importer, Irving Oil, but they did not say who originally underestimated the oil’s volatility or whether the mislabeling was intentional.

In a safety advisory letter issued Wednesday, Canadian authorities said the volatility of the oil likely was a factor in the explosion that occurred when an unmanned train rolled downhill into Lac-Megantic and derailed.

“The lower flash point of the crude oil explains in part why it ignited so quickly once the Class 111 tank cars were breached,” the advisory said. “Since product characteristics are one of the factors when selecting a container, this also brings into question the adequacy of Class 111 tank cars for use in transporting large quantities of low-flash flammable liquids.”

Officials with Irving Oil did not return calls for comment, nor did officials with Montreal, Maine & Atlantic. The Maine-based railroad has filed for bankruptcy protection in both the U.S. and Canada.

Canadian authorities questioned whether stronger rail cars should have been used to transport the light crude from the Bakken formation in North Dakota and Montana through Canada and Maine.

Still, they said the derailment, which killed 47 people and destroyed 40 buildings in Lac-Megantic, might have been just as deadly if the oil had been classified properly, given the train’s estimated speed of more than 60 mph when it derailed.

The oil was classified “packing group three,” representing the lowest risk of explosion for a Class 3 flammable liquid, Donald Ross, an official with the Transportation Safety Board of Canada, said at a news conference Wednesday in Ottawa.

But an analysis of the oil that was in the train’s 72 tank cars revealed that it should have been classified in packing group two, which represents a higher degree of volatility. Gasoline, for instance, is a packing group two liquid, Ross said.

Liquids classified as packing group two often are transported in rail cars with added safety features to reduce the possibility of an explosion, he said, although neither U.S. nor Canadian safety regulations require it.

Ross was not prepared to say whether proper classification of the oil’s explosive properties would have prevented or mitigated the disaster.

“We’re still investigating,” he said. “It’s a possibility that it had no effect.”

Class 111 tank cars, commonly referred to as U.S. DOT-111 cars in this country and CTC-111A cars in Canada, are the standard cars for transporting crude oil.

They have come under criticism repeatedly for their tendency to rupture in serious derailments. Sturdier, Class 112 tank cars are used to transport highly explosive gases such as propane and butane.

Class 112 tank cars are designed to remain intact in derailments at speeds up to about 20 mph, so the type of rail car likely would not have mattered in the high-speed derailment in Lac-Megantic.

Authorities said proper classification of the oil’s flammability was the responsibility of its buyer, Irving Oil. They did not say whether an Irving employee or someone else filled out the document incorrectly.

Ross said the oil, bound for Irving’s oil refinery in Saint John, New Brunswick, by way of central Maine, came from 10 suppliers along the Bakken formation.

Each supplier is responsible for testing the volatility of its own oil and classifying it on what is called a material safety data sheet.

Ross said the 10 sheets from the suppliers contained packing groups ranging from one (most volatile) to three (least volatile).

Two sheets were left blank and did not indicate any packing groups, he said.

A subsidiary of Miami-based World Fuel Services was the broker between the oil suppliers and Irving, but Canadian authorities did not specify whether the broker changed the volatility ratings to packing group three for the entire shipment.

A spokesman for World Fuel Services said in an email Wednesday evening that the fuel was “properly categorized as a Class 3 hazardous and flammable liquid and, as confirmed by TSB earlier today, the packing group assigned to this cargo would not have changed the manner in which it was handled, transported, routed or responded to by emergency personnel upon MMA’s derailment.”

U.S. Sen. Susan Collins issued a statement Wednesday about the investigation.

“We must look at regulations to make sure we are undertaking every precaution to save lives and to protect interstate commerce. Operational safety changes, however, are not enough to address these concerns,” she said in the release. “I will also work with the DOT Pipeline and Hazardous Materials Safety Administration as it begins to examine the existing fleets of tank cars used in shipping crude oil, which will include a thorough review of tank car design and making sure hazardous material shipments are properly identified.” 

J. Craig Anderson can be contacted at 791-6390 or at:

canderson@pressherald.com

Twitter: @jcraiganderson