Large Check Valves

[MechCoopStudent]

We had a 30" wafer check valve fail. After 2 weeks of downtime, we finally found the remains of the flapper and are operational again. To avoid this fun, we are replacing all the valves of the same style. Unfortunately, the 30" and 36" replacements will be too wide, and will require cutting the pipe.

Does anybody know of a company that can custom make 2 wafer check valves of this size? I have some calls out, but so far there are no replies.

 

[BigInch]

Used to be a company named Wheatly that made the best "BigInch" checks. Don't know if they're still around. I haven't been in the States in a long time.

 

[JimCasey]

I put "wafer-check" into Google and got 41000 hits. SOMEBODY will make you so large valves.

 

[MechCoopStudent]

Funny you should mention Wheatley, because they were the original manufacturers of the wafer checks. They have since updated their design, and made them thicker so they will no longer fit in the alloted space and require us to cut the pipe.

This will likely be a custom job, so if anyone knows of a company that does work like this, please let me know.

 

[BigInch]

Not sooooo funny. The best are the best and back then there wern't so many acceptable mfgrs to choose from. I suspect, that if you want a good heavy duty full swing check, there still arn't too many to choose from. I haven't speced any large checks for awhile now.

I presume these are flanged, since if they were weld ends you would have to cut and rebevel the pipe anyway and you might be able to fit them easier. Or maybe there's a bypass around them or something. Any reason you can't cut in a new valve? Or better yet, any reason you can't repair the old ones? Dumb question after they just caused you 2 wks down time I guess.

If they are guided and heavy disk for pig travel, don't try to replace them with a silly wafer check. The pigs will take them out of action at first bang.

http://virtualpipeline.spaces.msn.com

(A work in progress)

 

[BigInch]

Oh sorry, I see you did say "wafer" check. But you know, I think you really did mean to say "swing check", right?

 

[stanier]

Suggest you lookm at why the check valves failed. Likely cause is waterhammer. see

http://www.pipingdesign.com.

Noreva make short pattern non slam check valves

http://www.noreva.de.

This may solve your space problem and also stop the check valve failures and reduce maintenance on other equipment.

Geoffrey D Stone FIMechE C.Eng;FIEust CP Eng

http://www.waterhammer.bigblog.com.au

 

[MechCoopStudent]

We always could cut in a new valve, but then we would have to buy and install a spool piece, weld on flanges to the exiting line, and have all the welds x-rayed and pressure tested. If we could find someone who could make a valve of the same dimensions as the ones we are replacing, it would be more expensive than an off-the-shelf part, but overall cheaper and easier.

And as for the type, everyone here has been calling it a wafer check, and with the 36" one just 4 1/16" thick, they definately aren't full body.

They are used in a natural gas environment, so water hammer isn't a factor. The reason it failed is because the flapper plate (as we have come to call it) was attached to the pivoting bar by 4 bolts. For whatever reason, the bolts weren't welded, lock washered or even loctited in place, so they backed out over the last 7 years. Once one on the end wiggled itself out, the two in the middle sheared at the interface, and the last one bolt put up a good fight before failing.

The new design from Wheatley has a one-piece internal assembly. While this undoubtedly makes for a more reliable valve, it is thicker than the original and this proposes a problem.

Repairing was considered, but since the only logical explanation for this check valve is backup protection for an expander, we opted to replace it in the line without the flapper in order to start up the plant sooner. At the moment it is an orifice plate. At the turnaround this fall we are going to replace it with a functional wafer check, whether we have to cut the pipe or not.