Sulphuric Acid pipeline decommissioning
Sulphuric Acid pipeline decommissioning
(OP)
Hi forum!
We are decommissioning a 8" pipeline in service for sulphuric acid 98%, 1 mile.
we intend to drain the line and after neutralize, but the problem is reaching a sufficient draining of acid.
No drains are installed and the line and seems not piggable due to vertical expansion joints with 90°bends, so displacing the acid by nitrogen purging will leave lot of acid inside.... how to reach a good draining of low points?
do you know if is it possible to pig a line with expansion joints with 90°bends?
any idea on how to drain low points safely?
if we leave lot of acid inside, will the neutralization process give any trouble?
thank to all
We are decommissioning a 8" pipeline in service for sulphuric acid 98%, 1 mile.
we intend to drain the line and after neutralize, but the problem is reaching a sufficient draining of acid.
No drains are installed and the line and seems not piggable due to vertical expansion joints with 90°bends, so displacing the acid by nitrogen purging will leave lot of acid inside.... how to reach a good draining of low points?
do you know if is it possible to pig a line with expansion joints with 90°bends?
any idea on how to drain low points safely?
if we leave lot of acid inside, will the neutralization process give any trouble?
thank to all





RE: Sulphuric Acid pipeline decommissioning
If you have more acid than expected left in the line, the neutralization could generate more heat than was accounted for in safety reviews.
RE: Sulphuric Acid pipeline decommissioning
Now how you get the pig in and out is a different story, but for that you need to know what the piping arrangement is at either rend of your line. If you can drop a spool or valve out then this can be used to gain access, but the exot will need to be able to drain the acid away and accept dome has and acid and the pig.
However you need to be sure that there are no instruments sticking into the pipe, All the valves are full bore and wide open and there are no tees.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Sulphuric Acid pipeline decommissioning
I will show a drawing shortly
RE: Sulphuric Acid pipeline decommissioning
RE: Sulphuric Acid pipeline decommissioning
What fluid could you purge with that is non-aqueous and will not react with concentrated acid?
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P.E. Metallurgy, Plymouth Tube
RE: Sulphuric Acid pipeline decommissioning
simply it is a mile of piping with four vertical expansion loops (U bend) like this https://goo.gl/images/5aZcYn.
the pipeline starts on a foreshore area, overpass a public road and lays on a trestle offshore up to a marine loading platform.
clearly it was not designed for the current service..
so we could previously displace as much as possible acid with nitrogen, pig with a set of undersized pigs and then neutralize.
RE: Sulphuric Acid pipeline decommissioning
RE: Sulphuric Acid pipeline decommissioning
Just look at a few pipeline pig sites and talk to some people and you'll get one suited for that use.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Sulphuric Acid pipeline decommissioning
RE: Sulphuric Acid pipeline decommissioning
Is the main run the run or do you have right angle turns?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Sulphuric Acid pipeline decommissioning
RE: Sulphuric Acid pipeline decommissioning
RE: Sulphuric Acid pipeline decommissioning
However you could still use a sphere and also insert a gas connection at point B if you can.
If you can't drain down then you are a bit stuffed really in terms of getting anything in to clear it out.
You said the expansion loops were vertical but you've shown them horizontal?
What is elevation of the various bits?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Sulphuric Acid pipeline decommissioning
This adds momentum to push fluid but allows them to navigate difficult turns.
I have never done this personally so I can't offer any technical assistance.
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P.E. Metallurgy, Plymouth Tube
RE: Sulphuric Acid pipeline decommissioning
Littleinch, expansions loops are vertical..rotate the picture to left..
For the elevation, what do you mean with bit?
I will inform myself on piglets.
by the way, if the line is unpiggable, is it admissible to neutralize the line not drained? by adding small quantities of base, gradually over time?
thank you
RE: Sulphuric Acid pipeline decommissioning
Heat and gas generation are the big issues with neutralizing. doing it as quickly as is safe is usually needed.
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P.E. Metallurgy, Plymouth Tube