Pre-Emptive Pigging Design

[gkennedy34]

I'm working on a pipeline design where a single pipe will transport several different products. The pipeline is 8" in diameter and approximately 4000 feet long. There is some debate on whether or not pigging will be required in order to reduce the amount of contamination from product to product. I have been advised that pre-emptively designing the pipeline with 3X or 4X elbows will adequately allow for pigging and retrofitting with a pig catcher / launcher is all that will be required if, indeed, the line needs to be pigged.

While I've been working in the chemical industry for over a decade, I have very little pigging experience. Are there any other factors or considerations I should be taking into account here?

Thanks for your help.

 

[dtn6770]

It's been quite some time since I've messed with pipelines but if I remember correctly there different types of pigs. The requirements for a standard cleaning pig are different than those for a "smart" pig, one that can be used for pipeline inspections. If there's the chance the pipeline will ever be inspected in such a fashing it would be worth a call to someone who does that to see what limitiations there are.

I don't know if DOT applies to your situation but it might be worth a look.

 

[STYMIEDPIPER]

Contact or view their web site



O'Connor, Neil
Hygienic Pigging Systems, USA
1775 Mentor Ave
Cincinnati, OH 45212
(513) 731-6005

http://www.HPSpigging.com

 

[zdas04]

Typically batching is done with spheres which have no problem going through standard long radius elbows. Other sorts of pigs like smoother transitions. Manufacturer's of smart pigs are finally getting smarter themselves and almost all of the new devices will navigate a 6D radius hot bend. If you are really doing "preemptive pigging" (I like that term) then you should specify 6D radius hot bends and barred tees.

David

 

[GregLamberson]

It will depend on the products being transported and the facilities at each end. You may have to do batching with pigs or you may not have to.

With no other information, I would say go with 5D elbows. That being said, if you ever envision the need for doing any intelligent pigging, you would need to check with manufacturers for the radius thier pigs can traverse and design the pig traps accordingly (with the proper distances bewteen the barrels and your kicker/drain lines.

Greg Lamberson
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[gkennedy34]

Thanks, all, for the comments. I do not believe this pipeline will fall under DOT. I am also not anticipating needing to use smart pigs for thickness readings, etc., however I will ask my inspection group their input. My on-site "expert" mentioned spherical pigs but only in the context of our using a pig larger than that. I'll check into the website provided and will also consider the 6D radius bends.

Thanks again.

 

[GregLamberson]

gkennedy34

A couple of other general suggestions or tips - put a minimum of one pig length of straight run pipe between bends, outlets, and valves; keep internal diameters consistent, if you have tees, put bars on them; your launcher and receiver will be designed differently.

If you are going use spheres, the tees should be designed with constant internal diameter, oversized tee and a slotted outlet. The slotted outlets should be as short as possible, but provide a minimum of 75% of the outlet line cross-section area. This will allow sufficient flow area, minimize the pressure drop and minimize bypassing.


Greg Lamberson
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[STYMIEDPIPER]

Some other pigging web sites are listed on the previous thread378-177215

 

[BigInch]

All inspection pigs that I know of now will go through a 5D and many will pass 3D. 6D definately not required in my opinion.

If no inspection pigs will ever be run *, use spheres and 1.5 D bends.

* Beware that gathering systems regulations stand a good chance of revision and it just might be that internal inspection may be required in the future.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[GregLamberson]

Agree with BigInch, 5D's should be fine, will pass standard pigs and keep you away from induction bends. Spheres may be your best choice.

If you will be doing any batching with shperes, might want to look at automating the process by using spheres preloaded
into magazines. They can then be automatically inserted into the pipeline when required.

Greg Lamberson
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com