Piggable pipe problem 1

[embjh]

During construction a welded seam is now obstructing the pig for the weld was too hot. Are there any ways that a type of pigs can smoothen the internal pipe surface? As there is welding drop I assume that a steel brush pig is not sufficient...

 

[StoneCold]

embjh
I would make them cut it out and fix it. You are paying for a quality job wether it was an in house job or a contractor demand quality. I love welding so quality is a must on my projects, contractors may not like it but in the end I get my money's worth.

StoneCold

 

[embjh]

Very well, but first I need to know where the location(s) are. Is a gauging plate a known "best practise" as prover in welded piping?

 

[cgmrr]

Did the Contractor run a sizing gage plate when the line was completed? If the plate was the proper size and got through the pig should pass. What type of pig are you running? The type of pigs we use can be pushed through one pipe size smaller than they are sized for. If you are trying to run a linealog smart pig you may have a problem.

 

[embjh]

No gage plate was used to my knowledge. I will certainly add this to our engineering standards before commisioning of any piggable piping.

 

[zdas04]

How do you know that the pipe is obstructed? If you found the obstruction by sticking a pig, the only way I know to get the pig out is to find it and cut it out (typically you run a second pig with a radio if you can get enough flow around the first pig). Finding a truly stuck pig is a serious pain.

If poly pigs are coming in damaged, then I'd run "Turbo" pigs which are almost as forgiving as poly pigs but much more durable.

BTW I never run gauge plates because I wouldn't do anything with the data. Think about it, on a (say) 30 mile pipe you run a gauge plate that comes in beat up. Are you going to cut out every weld until you find the problem? Then how are you going to guarentee that when they make the line back up they don't do a worse job. I know that all of this cut-and-paste can be charged to the contractor, but you're building the line to move saleable product and while you're rebuilding the line you are not making money on it.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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