Written by Mark Latino, President, Reliability Center, Inc.
The incident took place in a chemical plant during a scheduled outage. A catalyst bed had a number of broken welds that needed repair. The maintenance supervisor, planner, and operations supervisor met and hammered out all of the specifics of the job. The job was scheduled and work began on the morning of October 12th. All the permits were in order and all the special equipment was in place to perform the work. People were assigned to perform the work were:
- Allen who was a welder in his mid forties. Allen was a very consciences hard working employee who had a lot pride in his craft. He liked to do things correctly (old school as they say). Allen had started work at the plant right out of high school and had been trained through the union trade school.
- Lee a young engineer was assigned as the tank watch. Lee had been with the company about 6 years. He like Allen was consciences and liked to do things correct. Lee had been through extensive safety training including the tank watch task.
- Don who was the maintenance supervisor over the job.
Things went well the first part of the day; we broke for lunch and returned about 12:30pm. Before entering the tank Lee used the oxygen meter to sniff the tank to make sure it was still safe and nothing had changed. After the test everyone went back to work and worked until about 2:30pm when we took a break.
Lee told Allen that he had to go to his office to check on some other work he was doing and that he would meet him at the job site when he was done. While answering e-mail the whistle sounded indicating there had been an accident. Before Lee finished his e-mail he received a text telling him about the accident and asked him to report to the job site immediately.
Allen had re-entered the tank without a tank watch present and was deprived of oxygen. He was hanging in the tank supported by his harness unconscious. Allen was removed from the tank and taken to the local emergency room. Allen was lucky in that he lived but the lack of oxygen had left him with some brain damage. The RCA investigation started that day same day.
The investigation revealed that Allen had violated safety protocol by entering the tank alone. The data collected showed no evidence of him ever violating this protocol. His only comments were “I don’t know what I was thinking”.
This is categorized as a Skill Based Error due to complacency/overconfidence and a lack of a complacency mitigation system being in place.