A worker has received burns during routine maintenance work on a processing plant in Western Australia.
The worker was cleaning a screen box connected to pipework below a thickener tank when the incident occurred, according to the WA DMP.
They first opened the drain valve to verify isolation before underdoing four bolts to open the screen box (inline filter) door.
“On opening the screen box door, the operator found the screen full of material; as he pulled the screen out of its housing a blockage upstream of the screen box dislodged,” the DMP stated.
“The operator was engulfed in 95 degree Celsius caustic solution, receiving thermal and caustic burns to his body and face.”
The report went on to state an emergency responder found the main isolation valve was open.
This was listed as the direct cause of the incident, as the screen box and associated valves were not isolated from the system, and that the process operator was directly in front of the screen box when the blockage dislodged.
There were also a number of issues contributing to the incident, the report explained.
“The isolation of valves was not verified through either a second and independent method of ensuring all valves were closed, or checking the effectiveness of each isolation point by separately observing a “change of state”,” it said.
Additionally, the operator mistakenly thought he had closed the main isolation valve but its function was actually being performed by a blocked pipe, while excessive scale had also built up inside the vessel after scheduled maintenance was delayed.
The report said It was difficult to determine the position of the main isolation valve (i.e. open versus closed), and that this was compounded as operators were not required to lock or tag isolation points for routine work.
It recommended better plant design in the future, and modification of the current plant to include facilities for proving an isolation point, as well as the installation of flushing systems to verify pipework.