Ball valve 5

[kpm21443]

I was seeing the specs sheet of a stock ball valve which was bought many years ago & I found the below line which I did not understand.

VALVE IS FOR STEAM SERVICE. Body is EXPOSED BONNET DESIGN.

Can any one interpret what is the meaning of the above line. The company from where the valve was bought has closed down & does not exist.

 

[zdas04]

Steam service usually means that the seats are metal. Exposed Bonnet probably means that it is a floating ball valve (i.e., process fluids, pressure, and temperature are against the packing gland when the valve is open) as opposed to a trunnion design where full process pressure and temperature are only in the body cavity during transients.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[gerhardl]

Additional to zdas04s' posting:

For lower pressures sealings could also be carbon/teflon with glass fiber reinforcement also possibly combined with (sintered?) metal. Exposed bonnet: steam pressure will reach/work against bonnet (body/shell) and thus also stem and body(if any) sealings.

Most probably floating ball, but a bit unclear, as trunnion mounted construction would be generally better, but inner body exposedas well.

'Steam service' qualification is not complete if not also max steam temperature (and then max steam pressure after steam table) is given; or the other way around with max temp. -> max. pressure (no overheated steam).

 

[bingbingwang]

for steam service, generally , means metal seat for high temperature and differential pressure (when shutoff).
exposed--- same as wetted to process fluid?? some ball valve are single seat ring, which is always wetted (exposed design), but double seat ring ball valves, the body and trunnion/bonnet bushing is not exposed to fluid (may leaks in, but designed to be not wetted).
hope it helps.

Get help and return with helps!!.

 

[Burdy]

I agree with the 'Wetted' explanation as being the same as 'Exposed'

 

[hsbcn]

I interpret that the "exposed bonnet" referece could mean a vented valve. Does that match what you see?

My focus is on corrosion-resistant, high-alloy valves for the petrochemical industry.