Welded vs. Bolted bonnet gate valves

[eml]

Our engineering specifications require welded bonnet gate valves for steam (and a variety of others) service. Our Operations and Maintenance groups however wish to use bolted bonnets in lieu of the welded b/c of the ease of maintenance. Other than the obvious additional leak path associated with a bolted bonnet, are there significant other reasons not to use the bolted bonnets in steam service ?

 

[MJCronin]

eml,

I suggest that you post this in the "Valve Engineering Forum" (or maybe you already have....)

Bolted bonnet valves have been in use on steam piping systems for many,many years. Welded bonnet valves are more typically used where there is lethal or toxic service (chlorine gas for example)

Welded bonnet valves are somewhat smaller than bolted bonnet......but must be typically "cut out of" the piping system in order to reseat. Large bolted bonnet valves can be worked on without removing them from the piping system.

My thoughts only....

MJC