AIChE: Safety Taken Personally
Tuesday, March 28, 2017 @ 02:03 PM gHale
By Gregory Hale
When Mike Broadribb talks about safety, he talks from experience. No, not just the kind of experience you get when you work in the industry for four decades, but the first person living through some serious plant accidents.
When he talks safety, it resonates.
Broadribb, senior principal consultant at BakerRisk, talked about two chilling incidents he was a part of during his talk Tuesday at the AICHE Spring Meeting and 13th Global Congress on Process Safety in San Antonio, TX.
One incident was a case of two fires with a Fluidized Catalytic Cracking Unit. He got a call one Saturday night from the refinery’s operators saying there was a fire from the preheater. Shift workers suspected a furnace tube failure. So, the solution was to isolate the fuel and feed lines on either side of the preheater. The goal was to depressurize the feed line. However, there was a build up of light hydrocarbon in the deodorizer effluent drum that siphoned over the preheater. The boxed in feed lines now over pressurized. The end result was two fires broke out and the control room, where he was working the problem, had flames breaking through. They were finally able to quell the issue. But it was a close call for his life.
The second incident was also with a Fluidized Catalytic Cracking Unit. When the incident occurred, the unit was in the process of starting up. “I had been working long hours and I was under pressure to get this unit started up because everything at the plant depended on this unit running.”
On the last day of the start up, Broadribb was doing a one-man PSSR (pre startup safety review) in addition to doing other tasks and they were getting ready for blank removal.
They were warming up the unit with steam when the workers removing the blank were saying there was too much and they should reduce the amount. They reduced the steam and the blank ended up lifted out. The pipefitter was trying to clean the flange faces when he found one of the riggers collapsed and then Broadribb heard some yelling and screaming so he went out to investigate and it turned out the pipefitter collapsed. As he was running to the scene, which was at least three stories up, an instrument foreman collapsed and fell on Broadribb from the foor above.
At that moment, Broadribb thought there was a gas leak. When rescue workers got to the scene they went up to the sixth floor area where other workers collapsed. They had breathing apparatus gear, but they were not using it. That led to four rescue works collapsing.
They called emergency services and people were running to the scene, some the breathing apparatus and some with not. In all, four people initially suffered injuries and four more rescue workers ended up injured, but all survived.
Case in Point
It turned out a pressure control valve, PCV5, ended up open to flare when it should have been closed while the blank removed. It also turned out a tailgas ended up shut off and it was routing back to the flare. The gas routing back was hydrogen sulfide (H2S), which is a colorless gas with the characteristic foul odor of rotten eggs and is heavier than air, very poisonous, corrosive, flammable and explosive. With the flare venting, it was sending out the H2S and the workers were dropping.
All eight workers ended up overcome by the gas and had to undergo treatment to recover. “We were very lucky,” he said.
A major crisis ended up averted, however, injuries ensued.
Broadribb talked about lessons learned:
• There should be one single competent person in charge of critical tasks
• There should be positive isolation when breaking critical containment
• There should be procedures for infrequent operations (like a startup)
• Share abnormal operations knowledge
• “It’s never happened before” is not a good excuse
• There should be a proper PSSR done and not one done while doing other tasks
• Too much going on for proper control.
“When you are doing a startup, you don’t want non-essential personnel on the site,” Broadribb said.
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