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valve class vs max.pressure

valve class vs max.pressure

valve class vs max.pressure

(OP)
your prevous input helped me quite a bit.

I have a question that is probably lame but can't seem to find an answer on the web.

I need a reference table comparing valve press. class vs. max. allowable pressure valve can handle.

Would any of you have this information, it would be greatly appreciated.

Thanks,

RE: valve class vs max.pressure

ASME B16.5 has families of tables for flanges based upon assorted metals at each flange class that tabulate temperature against pressure.  B16.34 has a similar family of tables for valves.  B16.47 covers flanges over NPS 24.

The metals are based upon ASTM/ASME materials.  You can also cross reference using UNS numbers.  As multiple tables exist for carbon steel I avoid the simplified vendor catalog data.  Anything more exotic than carbon steel has lower pressure rating than the steel tables at the same temperature.

RE: valve class vs max.pressure

You should be aware that the published pressure - temperature ratings referenced above define the limits for flanges.  Valves, depending on the type, often only meet these parameters at ambient temperatures.  In particular, soft-seated ball valves have a steeply decreasing pressure capability, with increasing temperature - (nowhere near the ASME B16.5 requirement).  The rate at which the maximum operating pressure declines with increasing temperature is also a function of the seat material - some polymers are better at higher temperatures than others.  You are better advised to obtain a catalogue from one of the better known valve manufacturers for their performance graphs or tables.  

RE: valve class vs max.pressure

BillBirch is correct.  The soft parts are not usually an issue below about 250 degree F.  Very carefull selection is required above about 350 degree F.  The fluid compatibility is a greater issue than temperature for wetted plastics, elastomers, etc.

RE: valve class vs max.pressure

ASME B16.34 (plants - inside the fence)and API Spec 6D (pipeline - outside the fence). They are the bible for valves.

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