A Stored Energy Near Miss

01 Nov 2021 at 20:44 // under Work Safety

I am going to cover an incident from earlier in my carrier when I made a mistake that could have lead to a very significant accident and it was only luck that nobody got hurt in this case. The incident in question happened more than 10 years ago now, I am covering it here because I believe it is better to be open about these kinds of incidents and help avoid future similar incidents.

During the maintenance period, it was necessary to repair the internal surface of the fume system. The section of fume in question was covered with tiles so an external contractor was organised to replace the broken and missing tiles.

There are two pumps , used to the supply water to the various jets which flush the material around the fume system. At the start of the maintenance period, both these pumps were electrically isolated and locked out. When anyone wanted to work on the equipment down stream of this kit, someone would add another padlock to the pumps and associate it with a permit. There were a lot of padlocks added to these pumps. A permit was written to cover the task and this included padlocks on the two pumps.

Work progressed in the flumes without incident however it was not possible to complete all the work before the water trials started. This was a period towards the end of the maintenance tasks when virtually everything gets re-energised and tested to ensure all the repairs have been successful. All the permits were carefully closed out and the isolations were removed. The job in the flumes was one of these jobs, so the work was left in the best state, all the equipment was removed and the contractors who were carrying out the task left site during the trials.

The trials progressed as planned and generated a list of work that was still outstanding. As agreed the contractors returned to complete the work on the flumes. A new permit was issued to allow the work to progress within the flumes and this included locking off both the supply pumps again. The new permit was pretty much copied from the old one, after all, why reinvent the wheel. Starting from scratch would just increase the likelihood that something gets missed. Unfortunately something was missed.

While the pumps were locked off, the isolation valves in the header were shut as well, locking water and pressure within the line. When had stopped for their break they climbed out of the flume. Just after the last contractor had climbed out, one of the jets opened up and water shot down the flume with great force. An instrument technician was working on the automated valve and had opened it. The instrument technician was perfectly correct with what they were doing. The valve he was working on was not supposed to be an isolation valve. It was not supposed to be holding back anything. The line was supposed to be fully empty.

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