INTELLIGENT PIG TRAP IN VERTICAL POSITION

[Imafidon]

Intelligent Pig Launcher is suggested to be positioned in the vertical position in an offshore topside design for reason of space constraint. Is this conventional and what are the pros and cons of such position.

 

[Ashereng]

I have seen a smart pig launcher where the pigs are "loaded" up vertically. I assumed it was for gravity feed, if nothing else.

Not sure if this helps you.

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Albert Einstein
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[zdas04]

With the proper clearance, a vertical orientation for the launcher is a good idea and is often done. The two problems that have to be addressed in the design are: (1) ensure that the closure door opens past 90 degrees so that it will stay open while loading pigs and that there are adequate lifting eyes on it to be able to close the heavy door; and (2) make sure that there is adequate clearance above the launcher to load a very long pig (generally you want to make sure that you can lift something that will just barely fit into the barrel).

Smart pigs bigger than about 6-inch are too heavy to manhandle so your platform lifting equipment needs to be able to get over the launcher barrel.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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[BigInch]

I'm not so sure about this one. Will the ] be in contact with the ball or are you trying to use a gate. What happens when the gate passes the nose, or the ball passes the nose? Will the pig tend to enter the hole in the ball and prohibit further opening, or will the passing of the gate force the nose down and to the left, or jam the valve on any other manner?

Going the Big Inch!

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[zdas04]

Designs for vertical pig launchers should have a pig stop above the valve that holds the pig in the barrel until the barrel is pressurized and the barrel-isolation valve is fully open. Then (usually pneumatic) rams disengage the pig stops and let the pig drop. If you let the weight of the pig rest against the barrel-isolation valve then bad things are sure to happen sooner or later.

David

 

[BigInch]

I've used those with spheres, but with a $500,000 intelligent pig, isn't it a even a little bit risky? I'd do it with a dummy first, then check for apparent damages. Have you actually launched one like this? Maybe the contractors have already done this. It might be good to ask them how they feel about it. All it costs is a phone call.

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[zdas04]

I've seen conventional pigs launched this way and never seen any extra damage. When I was around this kind of work (early '80's), a smart-pig run was $20k/in-mile (i.e., $200,000/mile for 10-inch) and we didn't have problems anywhere that would justify that kind of money. It is always a good idea to run a dummy pig in front of a smart pig anyway--you just don't want to discover that a million dollar robot has to be cut out of the pipe because it couldn't make a bend you'd forgotten was there.

David

 

[BigInch]

I've designed those for 7 platforms in Transco's gas line that was converted to a gas-liquid system in GOM around 1988. Those are auto sphere launchers. They're not usually intended for instrumented pigs. At least those wern't, which is why I had my reservations about using them for launching what can be a very long and heavy "contraption" that could have a possibility of extensive damage or hang up. I'd run a couple of dummys before I tried it with the real thing.

Going the Big Inch!

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