Pipe Plug with 1/8" drilled hole

[babyfatface]

P&ID shows a global valve with one threaded plug with 1/8" drilled hole.
I am curious that what is the usage of plug with drilled hole in the piping?

Thanks

 

[JimCasey]

It kinda depends where the 1/8 hole is drilled. And whether it is 1/8 diameter or 1/8 NPT.

It could be to ensure that the downstream pipe stays warm, supplying about as much steam as is taken out by the steam traps after condensation. This would be drilled through the plug.

It could be a gland-seal injection or leakoff point if the globe valve has lantern-ring packing. This would be drilled thru the bonnet and it would be an NPT connection.

It could just be a drain or a sampling point (try-cock connection)This would probablt be directly under the seat in the bottom of the bowl, also NPT.

 

[vpl]

To add to Jim Casey's excellent list:

If you have a nuclear application, and the valve is in a line which penetrates primary containment, the hole may have been drilled to prevent pressure binding and thermal locking of the valve.

Patricia Lougheed

Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.