valve class vs max.pressure

[cheaterbar]

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,

 

[JLSeagull]

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.

 

[BigInch]

You might find what you need here,

http://www.engineeringtoolbox.com/piping-tubing-systems-t_6.html

http://www.engineeringtoolbox.com/temperature-pressure-ratings-valves-d_1182.html

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[BillBirch]

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.

 

[JLSeagull]

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.

 

[DrJim]

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