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16" ANSI 600 Piggable Switch

16" ANSI 600 Piggable Switch

16" ANSI 600 Piggable Switch

(OP)
In the interest of cost savings, we are considering building one pig launcher and using a "pig switch" for bi-directional smart pigging of a 16" natural gas line. I've been able to find two manufacturers:

Globetech http://www.globetech-services.com/PigSysComponents.htm and

BKW http://www.bkwinc.com/pigging.html.

My question to the forum is do any of you have experience with a pig switch, and if so, what are your thoughts?

Thanks

RE: 16" ANSI 600 Piggable Switch

Most people get pig detectors with a switch and a flag.  You need to know the pipe wall thickness.

RE: 16" ANSI 600 Piggable Switch

I have bought these for projects.

http://www.apachepipe.com/

There is local indication (flag) and electrical signal.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: 16" ANSI 600 Piggable Switch

(OP)
I think I should clarify a bit more. “Pig Switch” seems to be the term that BKW and Globetech choose to call their ‘divertible wye’. We plan on using this so that instead of building a smart pig launcher to run a tool south and another smart pig launcher to run a tool north on the bi-directional line, we can build just one smart pig launcher that connects to the pig switch. This way, we can then make the smart tool go in either direction for about 60% of the cost compared to two launchers.

I came up with an arrangement of valves, ells, spool pieces, by-pass, etc., that would allow a tool to be launched in either direction with out having to shut down the line. The thing is that the client doesn’t want to have to deal with disassembly, possible spillage, etc. The whole thing seems pretty slick; I just haven’t found an engineer that has used an arrangement like this before.

RE: 16" ANSI 600 Piggable Switch

I'm more than a little confused about your lash-up.  Your stated goal is to be able to run a smart pig either direction in a line.  Any launcher needs a receiver so you have to have two devices that both look pretty much like a launcher.  If you purchase a bi-directional pig signal (a uni-directional pig sig will break off if you reverse the flow) then you can launch from the receiver and receive in the launcher, no problems.

My confusion comes from the idea that a pigging switch (which will work well to allow two lines to share a launcher) will do the same job.  The switch will have to sit somewhere (probably either end of the line if you want the whole line to be piggable in both directions) so for it to allow the pig to either run north or south you'll have to run a second line to the other end won't you?

If you're interested, I have a document under "Samples" on my web page called "Rules of Thumb for Gathering Equipment" that has a discussion of pigging equipment that might be useful (you're welcome to the document, it is an accumulation of stuff that has worked for me over the years).

David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
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

RE: 16" ANSI 600 Piggable Switch

On most of our pipe lines, we use one launcher to one receiver. I haven't seen multiple launcher/receiver stations where we work.

We do have combination receiver/launcher, but they run in the same direction. So, we receive a pig from up stream pipe, and then use the same tube to launch it downstream.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: 16" ANSI 600 Piggable Switch

(OP)
Thanks for all the responses.

The line we are considering using the pig-switch for is part of a gas storage facility. The line will carry saturated brine north and south from the facility to several brine water disposal wells.

The conventional arrangement is where a single line comes from the brine water pump, splits off into two lines where one runs north and another one south. These lines would each then have a pig launcher and a receiver set up in the conventional manner.

A non-sealing pig switch/switchable diverter would allow us to have a single pig launcher, the pig switch, with one leg of the wye going north, and the other going south, each to their respective pig catchers.

At approximately $150K for each pig launcher and a pig switch around $30K, the single launcher/pig-switch arrangement makes much more economic sense. The thing is none of the engineers either here at my company or others I keep in touch with have any knowledge of pig-switches. I understand this is not a common arrangement – have any of you ever seen something like this?

--Thanks again for your help

RE: 16" ANSI 600 Piggable Switch

I've designed a bunch of systems where multiple launchers share a recieiver (one case 6 launchers went to one receiver).  

What you've described is two separate lines sharing a receiver.  There are several ways to do this with pipe and fittings, but all will cost more than $30k.  I'd go with the pig-switch, contact the vendor for references.

David

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