Mothballing - Air gap vs Blanking
Mothballing - Air gap vs Blanking
(OP)
We are currently working on mothballing a PSM covered plant. When I've done mothballing at past companies, I've always been taught to air gap the equipment in order to call it mothballed in PSM but there is a question if we have to air gap it or if slip/pancake blanks would be adequate. I don't believe there is a regulation on this, but was curious about what is considered the industry standard.
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RE: Mothballing - Air gap vs Blanking
What's PSM?
Some sort of positive isolation will allow you to use inert gases in vessels etc. So long as the slip or spectacle is clearly identified as Do not move or remove / MOTHBALLED written on red Tags, then I see nothing wrong.
Air gap becomes a bit harder to re commission and is lower risk, but if it's documents and marked properly the difference is small.
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RE: Mothballing - Air gap vs Blanking
I'm surprised you don't know this - I thought your background was in O&G in the USA.
PSM is USA's OSHA mandated program for "Process Safety Management of Highly Hazardous Chemicals" -29 CFR 1910.119.
Any site with above threshold quantities of toxic materials or >20,000 lbs of flammables qualifies as a PSM-covered facility, so it is a very common regulatory requirement. I know there are (or were) some exemptions in the drilling wells, but thought most O&G was covered. Perhaps I am mistaken.
MP08 - I do not know of any PSM standard that specifically address decommissioning or mothballing. You have to satisfy an auditor that you meet the requirement that the limits of the covered process are defined. Without an air gap, I am not sure if an auditor would necessarily say you were not connected to the process. One reason for doubt would be corrosion and eventual pinhole leaks in the blind causing the equipment to become "live" again. As far as I know there is no "hard" standard - it's up to the process owner to define. Hopefully the government agrees with you if that is the route you take.
RE: Mothballing - Air gap vs Blanking
PSM sounds much more like COMAH regulations in the UK and Europe.
The blind flange / spade should not be the primary barrier and hence there should be a locked off valve etc as well which helps prevent any circulation of corrosive materials. I can't recall hearing about corrosion of such taking place but there may be the odd one.
Clearly air gapping is superior to simply spading, but whether it is needed is another matter altogether.
The attached is a useful guide but doesn't have much to say about "extended isolation" as it calls it and notes that the selection tool isn't valid!
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.