The oil tanker cars involved in Wednesday’s/last week’s train derailment near Heimdal (hyme-doll), North Dakota caught fire but did not explode. That could be because the oil met state standards designed to make it less explosive.
A spokesman for the company that owns the tank cars says the crude oil on the train had a vapor pressure well under the state standard.
In April, North Dakota began requiring companies to remove the most flammable gasses from crude oil and lower its vapor pressure before loading it onto trains. The goal was to prevent an explosion during a crash. But North Dakota Governor Jack Dalrymple says other factors are more important in preventing a derailment.
"The biggest factors are keeping the trains on the tracks first of all, and trying to make this equipment as safe as it can possibly be."
The train cars involved in the crash are set to be phased out by 2020 under new rules released by the U.S. Department of Transportation on May 1.
