scope:

Description of Driving Event:

A tube trailer was being filled with oxygen with a 1000 psi differential between the trailer and supply when a flash was observed in the area of the remotely operated control valve. A subsequent rush of gas and fire followed. The fire continued for about 40 seconds and was extinguished by the onrush of gas from the ruptured stainless steel manifold lines that had been burned off.

The investigating board concluded that the nylon seats in the valve had deteriorated to the extent that the ball was able to vibrate freely under the high flow conditions present. The vibration would most likely be severe while attempting to flow oxygen against a closed ball valve with missing or deteriorated seats. This would have generated sufficient energy through impact and heat to cause ignition.