Pig lauchers 1

[Kandan]

I have a question on pig launchers.
Do pig launchers and receivers always require a block and bleed arrangement for pig retrieval

 

[Homayun]

Kandan,
My judgment is that you'll need them to completely isolate your pigging activity.

 

[Latexman]

If you mean "do pigs have to be retrieved manually"? The answer is, no. Pigs can be automated. You'll still need a way to isolate the pig launcher and catcher, because pigs wear out and need to be changed and, as we all know, things go wrong sometimes.

Good luck,
Latexman

 

[Hookem]

Kandan: In short, no. One does not always need isolation valves. I just finished putting in a pipeline with L&R's without isolation valves. The key is that the service is water, being pumped from a canal to storage tanks, AND operations willingness to take the pumps offline (thus removing the source of the pressure). It also helped that the L&R were higher than the buried line!

 

[MatthewD]

I am going through a similar issue now and according to our client a double block and bleed is required on our recivers and launchers. So it depends on who you are doing the work for or what your company's standard practice is

 

[svanels]

If it is water, the 'headache' is minor, compared to the explaining your company has to do in case of gasoline, crude, fuel oil or some other toxic/flamable product spill to stake holders, press, government and neighbors.

Steven van Els

 

[rusman]

Hi

It does depend on the pressure rating of your system.

What normally we used, for liquid system having 600# and above, a double block and bleed valve is required.

For gas system, for system having 900# and above, a double block and bleed valve is required. If H2S in the gas stream is high (SOUR Service), system having 600# and above, double block and bleed valve is required.

Thanks

Rusman. CEng, PEng
Process