Pig Lauchers/Receivers Design

[Chiller]

Can any one please direct/advise me how pig launchers and receivers are sized. Our clients have given us the diameter of the traps and have asked us to specify the lengths. Is there specific ratio of lengths that we must adhere to? Is the eccentric cone angle and length critical? Our client has also specified a min total length of 7m.

Appreciate ANY assistance/advice!!!!!!

 

[TD2K]

The trap length is usually determined by the type of pigs they want to use.

Traps for launching spheres are usually the shortest, intelligent pigs are the longest. I would talk to the owner and establish the basis for pigging, single cleaning pigs, multiple pigs, intelligent pigs, etc. You can then talk to a vendor(s) and get the dimension(s).

If you are going to intelligent pig a line, there are other constraints to the design of the piping/pipeline line bed radius, again, the vendor can help you there.

 

[LSThill]

Chiller (Mechanical)

Need more information (1) is the Pig Lauchers/Receivers Design to be installed on a offshore platform alway in the vertical postion with 5D or 9D bends. (2) in the horzitional postions?

Leonard@thill.biz

http://www.thill.biz

 

[Chiller]

The launcher/receiver are both horizontal for intelligent pigs and are onshore.

Some more questions:-
1) Does it make a difference if it is offshore?
2) Would I be correct to assume that the cone can be concentric if its vertical?
3)Is there a specific design code for pig traps or is it
designed to a recognised pressure vessel spec?
4)What are pig signalling devices?

Many thanks.

 

[TD2K]

1. It doesn't really matter if the trap is onshore or offshore. Offshore, room is more tight so traps would tend to run smaller compared to onshore installations where some additonal length is not a major deal.

2. Is this the reducer at the front of the trap? This is eccentric on the ones I've seen, especially large ones. Small ones, especially for cleaning pigs could be concentric I suppose.

3. I've seen them designed usually for a piping code, can be designed using B31.3 for the facility if applicable or the pipeline code (B31.4 or B31.8) they are attached to. It depends where they are, if it's in an open area you may be happy using the pipeline code, if it's in a process building, you may want to use B31.3. They can also be specificed as Asme code vessels if you or the client want to go that route.

4. Pig signaling devices simply tell you the pig has passed that point. They are usally put on the inlet to a trap and another one 1/2 mile or so upstream on the pipeline to alert you the pig is coming. They can be purely mechanical or electronic if you want remote signaling.