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LENGTH OF PIG TRAP MAJOR AND MINOR BARREL
- Thread starter 54231
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TD Williamson more or less invented the pigging industry. Their pig sigs are really reliable.
That being said, I think the dimensions of the traps in CRG's reference are wrong for today's requirements. I've never liked their launcher not having a minor barrel to speak of, the concentric reducer is just dumb, and the major barrel is pretty short.
My rule of thumb is to make the barrel about as long in feet as the nominal pipe diameter is in inches (i.e. a launcher or receiver on a 6-inch line would have the major barrel 6 ft long). I like to set the launch tube (minor barrel) at 4D (24 inches on a 6-inch line). These dimensions let you launch most smart pigs without having to kludge on an auxillary barrel.
If you're rolling your own pig-trap designs, spend some time thinking about kicker and bypass line sizing. I've worked up some sizing that satisfies most client's maximum pressure drop requirements. The numbers are on my web site under "Samples" as Rules of Thumb for Gathering Systems. That might give you some direction.
David Simpson, PE
MuleShoe Engineering
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
That being said, I think the dimensions of the traps in CRG's reference are wrong for today's requirements. I've never liked their launcher not having a minor barrel to speak of, the concentric reducer is just dumb, and the major barrel is pretty short.
My rule of thumb is to make the barrel about as long in feet as the nominal pipe diameter is in inches (i.e. a launcher or receiver on a 6-inch line would have the major barrel 6 ft long). I like to set the launch tube (minor barrel) at 4D (24 inches on a 6-inch line). These dimensions let you launch most smart pigs without having to kludge on an auxillary barrel.
If you're rolling your own pig-trap designs, spend some time thinking about kicker and bypass line sizing. I've worked up some sizing that satisfies most client's maximum pressure drop requirements. The numbers are on my web site under "Samples" as Rules of Thumb for Gathering Systems. That might give you some direction.
David Simpson, PE
MuleShoe Engineering
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
I am not sure why all of TD Williamson's sketches show a concentric reducer; however, if you read the first page of the link, under Features, it states, “An eccentric reducer on all Launchers to assure proper pig line up.” On the first page of the link, under Descriptions, it states, “Our standard design will accommodate most types, including displacement, batching and cleaning pigs.” No mention was made regarding their standard design being suitable for smart pigs. Also of interest is that TD Williamson’s standard design is capable of launching one pig and receiving two pigs. 54231, the question is what type of pigs are you designing your launchers/receivers for? Do your design applications make smart pigs a standard for design?
DrillerNic
Petroleum
From memory, when I was a pipeline engineer, Pipetronix's intelligent pigs were the longest.
I'd recommend designing for and intelligent pig just in case, and contacting the all intelligent pigging companies for their current pig dimensions and designing off the longest one for the major barrel length as future intelligent pigs will almost certainly get shorter rather than longer.
I've also seen shorter minor barrels on the reciever and longer minor barrels on the launcher, but I don't have much operational pigging experience to be able to say if this kind of thing is good, bad or neutral.
I'd recommend designing for and intelligent pig just in case, and contacting the all intelligent pigging companies for their current pig dimensions and designing off the longest one for the major barrel length as future intelligent pigs will almost certainly get shorter rather than longer.
I've also seen shorter minor barrels on the reciever and longer minor barrels on the launcher, but I don't have much operational pigging experience to be able to say if this kind of thing is good, bad or neutral.
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