Welded Bonnet vs. Bolted Bonnets

[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 ?

 

[keyardee]

Hi eml
seal welded bonnets are in vogue in petroleum industry and chemical industry.Here also the valves will be having double glands with suitable sealing fluid passing through them.(weeping glands).But in steam application the welded bonnets seem to be overspecified if not a luxury.Ultimately the individual application will decide what type of valveis to be used.