How to change valve under pressure ?

[JohnSolid1]

I have 1/2" (male) valve that I have to change under 40 bar pressure !!

There is no way to close this part of gas line (natural gas).

It's actualy one-direction stop valve in shape of usual bolt with high six-side head.

How do I change this valve ?
Is there any tool for this operation ?

Thank You in advance ..

 

[hacksaw]

you don't!

There are specialist companies that do it for you. It is pretty amazing what the do.

 

[zdas04]

JohnSolid1,
Go with hacksaw on this one. There are so many ways to kill someone with 40 bar that it doesn't bear contemplation. The experts will find a way to do something like installing a lubricator to insert a line stoppel and pull the valve out. Replace it with technology that works.

There is no cookbook way to do this and it takes a lot of experience and really specialized tools.

David

 

[SooCS]

Try Cosasco. They supply tools to retrieve or hot tap piping system.

Good luck.

 

[jte]

John-

I agree with the other posts - It isn't worth getting someone killed to try this without a lot of experience. Even with an experienced contractor, you need to have a contingency plan in case something goes wrong. The worst case is usually that the line breaks while its being worked on. The plant operators must be ready with a plan in case this happens. Our on site contractor who handles these types of jobs for us is FlowServe. Check them out at

http://www.flowserve.com/srvnrepair/line_stop_ani.asp

jt

 

[hydrodude]

Try Cudd Pressure control they should be able to freeze the line by pumping in a gel and using dry ice, very effective in changing out wellheads

 

[scanguy]

These guys have some pretty awesome techniques for pipe isolation, their called Car-Ber Testing. They may have more suggestions and have offices all over.

http://www.carbertesting.com

 

[JohnSolid1]

I would like to thank all for replys.

From answers above, the most I like is to inject some kind of gel, and freze it inside of gas line. Now I would like some recomendations what kind of gel, or other medium I could use for this, where can I buy it (I'm located in Europe) and other useful hints.

Thank you all, once again..

 

[lilliput1]

I suggest also that if possible open up all other valves drawing from the line to reduce the pressure.

 

[tickle]

Can I ask why you need to change out a 1/2" valve? The cost of performing the "hot work" may be significant and another alternative be considered.