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Pig Trap and pipeline diameter differences

Pig Trap and pipeline diameter differences

Pig Trap and pipeline diameter differences

Dear All,

We have a Client whom would like to utilize an existing 14" pig trap they have to hand and install on a new 12" sour gas pipeline. This would save them money by not having to purchase a new 12" pig launcher and receiver.

Is such a combination recommended or even possible?. Presumably the only way it would work is to use a dual / bi diameter pig capable of 14" (for the launcher and receiver) and 12" (for the actual pipeline). are there any risks out of the ordinary with this setup

Thanks in advance

RE: Pig Trap and pipeline diameter differences

Holy moses, what a cheap skate.

I'm assuming you mean the minor barrel is 14 and 12 respectively.

Recommended? No
Possible? barely

Risks? The pig getting stuck at the 14 to 12 reducer on the way oh or stopping in the minor barrel on the way out.

Your only hope is that the ID between 14 and isn't as big as normal as this is where it switches from nominal OD to actual OD.

But it's still a terrible idea.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pig Trap and pipeline diameter differences

Hi, thankyou for response.
I was also thinking along the same lines.

Yes, the pipeline is 12 inches diameter and the pig trap minor and major barrel is 14 and 16 inches diameter respectively.

What do you mean by the term spoon with regards to the pig leaving the trap.

Forgot to add, they need to use an inspection pig instead of a simple cleaning pig which I guess makes the idea even less practical.


RE: Pig Trap and pipeline diameter differences

Typo. I meant that it might stop in the minor barrel and block closing of the pig trap valve

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pig Trap and pipeline diameter differences

You need to look at the ID of the 14" and the 12" systems to see if this is within the range of the pig.

If the 14" was particularly heavy wall pipe (say Sch 120 or 160) and your 12" pipeline much thinner ( say 12.7mm, then the IDs might get close enough to make it work.

But it's still a bad idea.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pig Trap and pipeline diameter differences

LitteInch, thanks for your advice!

RE: Pig Trap and pipeline diameter differences

Just thinking Out Loud ,ss far as i know,in order to simplify the handling the larger diameter pigs, the trap section sometimes equipped with a tray which can be rolled in. In this case ,the bigger size diameter of the barrel needs to be increased by an extra amount .

This is copy and paste from the book THE PIPELINE PIGGING HANDBOOK,Jim Cordell and Hershel Vanzant ''The main body of the pig trap, sometimes referred to as the 'barrel', consists of a section of pipe which is larger than the nominal diameter of the pipeline. This section houses the pig and, being oversize, allows the pig to be inserted or removed more easily. The barrel should be 2" over the pipeline size for pipelines in sizes up to 10". For pipelines from 12" up to 26" the barrel diameter should be 4" larger than the pipeline and for pipelines 28" and above, the barrel should be 6" oversize.'.

Apparently , there is a need for an extra Con.Red. 14'' X 12''. However, the reducer must have a gradual transition, with a slope of 1:5. Reducers having very abrupt transitions are not acceptable.

NEW ENGLAND MAXIM Quote ' Use it up, wear it out; Make it do, or do without.'…

RE: Pig Trap and pipeline diameter differences

Thanks for the reply. So the major barrel of the pig trap is probably 16". Importantly the minor barrel is 14" and the pipeline is 12". Im not too concerned about the major barrel, its the transistion between the pressurized 14" minor barrel to the 12" pipeline which the dual-diameter pig has to make. Thanks for the point on the the reducer gradient, I did not consider this at al1. NExt step will be to ask a Vendor

RE: Pig Trap and pipeline diameter differences

Ask the vendor what exactly?

You haven't stated what the ID is of the 14" and 12" systems are. That's the key here.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

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