Case 6

A group of workers were tasked to remove a defective valve on an 18" raw water pipeline. The defective valve was located at an elevation of 20 feet in a pipe rack - not readily visible to a casual observer.

The workers made their work area safe by shutting off a valve about 150 yards upstream of their location.

The maintenance workers were scheduled to finish their work by 3 PM. Unfortunately, they could not finish the work on schedule (as is very common,) and decided to work a few extra hours to finish their job.

A 4 PM, the operational shift changed.

The day before, the second operations crew had been informed that by the time they come on shift the pipe line will be back in service. That is what they were expecting.

One of the operators on the new incoming shift noticed that the isolating valve was still closed and there was no warning tag on it. He assumed that the maintenance work had all been done, and the earlier shift did not have time to put the pipe back in service.

The operator proceeded to put the pipe in service by opening the valve.

Guess what? The maintenance workers were surprised to hear pressurized water thundering their way.

In their scramble to escape, one worker fell to the ground and suffered serious injuries.

Cause: Exposure of workers to uncontrolled energy (water under pressure.)