Stuck Pig in Pipeline

[pcog07]

Hello, what would happen if a pig was put in the pig launcher backwards e.g. instead of the cone or bullet shape end inserted first it was the flat shaft that was put in first? It's a 4" rubber pig with 3 cups (or cylindrical rings in series around the shaft and about 10" long. Would it stay stuck in the pipeline until you push gas in the next junction upstream of it to go back into the launcher? Is there any other solution you guys could recommend? Thanks a bunch.

 

[SNORGY]

I just HAVE TO be the first to ask...

Did someone actually load a pig with the pointy part facing the wrong way?

As for what will happen...

It depends how far it has gone. If you have enough line pack pressure on the pipeline side of the pig, you might try blowing down your pig launcher pressure, carefully, to see if you can catch it back in the launcher. Are there pig signal indicators in your system?

 

[LittleInch]

So which is it? Cups or discs? Can you post a photo or a link to the suppliers site?

With cups it is unlikely to move very far, but with discs it won't make much of a difference.

Can you close the pig trap valve? A few more details please.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[pcog07]

Hello guys, I don't know for sure whether it was sent with the pig orientation in reverse. I'm just speculating right now since we can't push the pig past the first junction downstream of the launcher. I was trying to attach the picture of the pig we sent but I can't upload it on this site. The link shows the batch pigs and it's similar to the red one with discs around it. The slight difference is that our pig has a more rounded cup-like front with just two discs behind it. Sorry for the poor terminology.

We can close the pig trap valves. We were able to verify that the pig was in the pipeline since the launcher is empty. Maybe next time it would be wise to inject even 0.5 m3 of methanol ahead of the pig to prevent any hydrate issues. We pig this pipeline every month so I can't see wax or foreign material that would accumulate that fast to cause the pig to get stuck unless otherwise third parties are dumping wet gas that should have been dehy'd. Thanks for your time.

http://www.hmpsi.com/images/batch.jpg

 

[LittleInch]

The picture looks like a bi directional type so its not that. You say first "junction", do you mean a tee?

What size? Assuming it was designed as a barred tee, the only issue you may have is that the bars have fallen off and you pig has hung up on the tee.

Almost impossible to do anything other than cut it out. You can try reverse flow back into the pig trap, but start to think about depressurisation and cutting.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[pcog07]

Hello guys, the junction I was referring to is the first riser (downstream of the launcher) with other pipeline that ties into it. We were finally able to retrieve the pig by equalizing both pressures upstream and downstream of the pig. Then, we injected methanol in both sides of the pig. Compressors were then started to push it again and finally it started to move. The pig was retrieved and the receiver had a lot of hydrates. We found out that there are liquids that used to be tanked (and trucked out from upstream compressor sites) that started flowing in the pipeline.

The problem can be traced from water in the line from the condensate and dehy systems that are not working properly. It was highlighted that methanol must be used upstream of the pig to prevent this from happening again.

Thanks again for your time.

 

[SNORGY]

Kudos to you and your operations folks for retrieving the pig safely without creating a sonic speed potato canon. Glad it worked out.