Crude oil aboard a BNSF train that derailed in North Dakota on Wednesday caught fire even though it was less flammable than required by a state law that took effect last month. Test results sent to federal investigators and seen by Reuters show the state’s new rule may not be stringent enough to significantly reduce the risks of fireballs after derailments of trains carrying crude. In this crash, the crude on board contained about 20 percent fewer volatile gases than regulations mandate. The oil, transported in tank cars owned by Hess Corp, had a vapor pressure of 10.83 psi, according to test results. This pressure is less than the new threshold of 13.7 psi. State regulators have used vapor pressure as a proxy for measuring the amount of flammable gases known as light-ends that are present in crude. Samples of the crude oil involved in this latest […]