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pig stuck in pipeline

pig stuck in pipeline

pig stuck in pipeline

(OP)
During water filling in pipeline we lunch 2 pigs in the pipe one of them arrived in the receiver while the other one seems to be stuck somewhere. The question is can we start the hydrotest and apply the pressure while the pig still inside?

Note that theoretically the pipe is full with water.

Appreciate if someone can advise me.

RE: pig stuck in pipeline

Q: Are you also planning to start operation with the pig in the pipe? If not: Why not get the pig out first and begone with the doubt?

IMO if you measure the pressure in both ends and its only one pig then there cant be a "low pressure pocket" and it should be OK. You have to consider if you will pressurize from both ends though?


Best regards

Morten

RE: pig stuck in pipeline

Not knowing where the pig is stuck (and what fluid is on either side of it) would make me REALLY nervous. The pig has a different compressiblity than the water so it may act like an air pocket would (i.e., pressure bleeding off at an inconsistent rate). You didn't say what kind of pig it is, so I'll assume you are using an uncoated foam pig which seems to be the most common pig for use in conjunction with hydrotests. These things are MOBILE. I once put a 10-inch foam pig through a 2-inch vent (it wasn't pretty as it came out, but it came out). Are there any line drips or other dead legs in the system that it could be hiding in? I'd study the fabrication drawings pretty closely to see if I could find a logical place for it. If you have line drips, then you can open the drip blowdown and see if the pig plugs the blowdown line. If that happens then you are good to run the test.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

RE: pig stuck in pipeline

(OP)
Thanks all

the reason why we dont take the pig out because our contractor dont want to take the water out from the line and fill it again.

the pig is by-directional type.

the idea is to apply the pressure and monitor it to make sure there are no pressure difference between both ends.

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