Release at a cooling system of a polymerisation plant

While de-plugging a cooling circuit, a blockage suddenly released, causing a heavy movement of a flexible hose connected to the system. The flexible hose hit several small pipes and one employee standing nearby. Due to the broken pipework there was a release of hydrogen and butane for about five minutes. Sprinkler systems were activated, no ignition occurred.

The INITIATING cause was a mechanical failure, the root cause is not reported. However, an abnormal situation had occurred previously during the day, hinting probably at some human and/or organisation error.

cooling circuit, hose, pipes, Plastics and rubber manufacture

De-blocking of a cooler was done by using water at high pressure, but with great difficulties. During the day, a nitrogen feed had been temporarily opened out of fear for an explosive atmosphere in the receiving tank-truck. When the water pressure was put on the system again, a nitrogen plug was probably compressed. When the blockage released, the plug was ejected with great velocity, causing the connected flexible hose to move violently.

One employee standing nearby was hit by the flexible hose. Loss of hydrogen and butene for several minutes. Limited loss of polyethylene powder and hexane. Estimated production loss: 7 days.

Sprinkler systems were activated to contain hydrocarbon cloud and to prevent ignition. Leaking pipes were blocked after five minutes. The injured employee was hospitalised.

An explosion could have destroyed the entire polymerisation unit.

This is a classic case of injuries and damages caused by a whiplash of high-pressure hoses. Best practice and work procedures require the use of hose whip restraints (whip checks) to secure the hose and prevent it from whipping during a failure. It is recommended to regularly check if the hoses are securely anchored and to wear appropriate PPE. A lose, unrestrained hose shall never be operated.