This month’s CCPS Process Safety BEACON is about energy isolation practices in chemical process units and although I personally think they missed the mark on this one, it is a PERFECT EXAMPLE as to why many businesses involved with processing Highly Hazardous Chemicals/Extremely Hazardous Substances do NOT allow for “single valve isolation”, especially when there is NO MEANS to verify the single valve is providing a Zero-Energy-State (ZES) and the process is “live” on the other side of the valve.
The “take-aways” from the publication are right on the mark, I just wish they would have dwelled further in “energy isolation” practices in process units. I absolutely prescribe to the practice of NO OPEN-ENDED LINES!!! Had this policy/practice been in place, this incident would NOT have gone down the way it did; HOWEVER, it would NOT have prevented an unintended LOPC event, as the worker(s) removing the blind to re-install the instrument would have found a BIG SURPRISE. I just wish they would have mentioned the Line/Equipment Opening Process Practices, Means to verify a ZES, etc. This is why EACH OPENING needs a permit – EVEN removing a blind that was installed for the work!
We should also recognize that when the work we are doing involves a “header”, we ALWAYS MUST ASSUME reverse flow. When this process was opened up, the header was not being utilized, therefore there were no indications the valve did not close (even though it appeared it did). Once Unit 1 began venting to the T.O. some of the hazardous/toxic gas(s) began venting into Unit 2 where the instrument has been removed.
SAFTENG members should really take a few minutes and understand “energy isolation” (e.g. LOTO) in a chemical process is VERY DIFFERENT from the traditional LOTO found in assembly-line style manufacturing.
I would also encourage SAFTENG members to look at my Line Break Presentation from several years ago at the ASSE Annual conference.
ASSE Safety 2016 – Line Break Presentation