Steam Valve Body Holes

[Matador]

I see ten inch 150# valves being modified and something doesn't seem correct but I have not been able to find anything in the code which says this can not be done.

The ball valves are used as blow valves and the ball sticks with gummy material. They drill a hole in the side of the valve body, weld a 3/4" fitting, then connect it to a 150# steam supply to inject steam & flush the area between the ball and casting body & keep it warm.

I think the valve pressure rating should be derated but I cann't find anything specific in the piping code.

Assistance or ideas will be appreciated.

 

[NozzleTwister]

Purges like you describe are quite common and if done correctly, no derating is required.

For details refer to ASME B16.34 Valves - Flanged, Threaded, and Welding End. Section 6.3, Auxiliary Connections. Also refer to Fig's. 1, 2, 3 & 4 for port locations.

NozzleTwister
Houston, Texas

 

[Matador]

We don't have a copy of ASME B16.34 on site & I can't find any info on the web.

Would you know what sort of NDT has to be performed after the alteration?


Thanks in advance.

 

[NozzleTwister]

It can be purchased on-line from ASME. See the link below.

http://catalog.asme.org/home.cfm?SEARCH=b16.34&SearchWithin=1

NozzleTwister
Houston, Texas

 

[proinwv2]

I would suggest that you also look at ASME Sec VIII in the course of your investigation.

Further, a field test, at 1.5 x WP could alleviate your concerns.

Paul Ostand

http://www.ostand.com