DESIGN PRESSURE AND DESIGN TEMPRATURE. 2

[skengg]

Hello,
i have one doubt which i tried to find another place but still confused in clarity of answer. so i want to know design pressure & design temp relation. like i know that design temp. is max. temp. at which valves or any pressure vessel intended to design.i am giving you an example that give you clarity of my doubt, suppose i want to design a valve of ASTM A216 Gr. WCB material. By 16.34 pressure/temp. chart. we know that 425 deg. c is max. temp. recommended to use. so if i take 425 deg. c as design temp. then what should be the Design pressure like Max. allowable working pressure at room temp. or MAWP at 425 deg. c. i hope you all get it.

 

[mk3223]

A quick reference is to do the search of the Eng-Tips forums for related discussions in the past.

Basically, the design P (MAWP) at the design T is specified by the Project according to the Process and Operation requirements. And then, the material is to be selected to match these requirements, but not the other around.

 

[skengg]

thanx

 

[saplanti]

If you design off-the-shelve valve I would suggest to follow flange design standards, use the same design pressure for the same/similar carbon steel group. If you have ASME B16.5 it will give you guidance for this material group.
In addition to that you may use ASME B16.34 for the this materials for the design pressures given in the flange standards. If welded valve is used the application is the same.

If you design a unique valve you need to follow the design specification of valve and, the specification of the line that the valve is going to be attached. But mainly this kind of specifications call for Flange Class, materials, design/operating pressures and temperatures, corrosion allowance etc... You need to discuss with your client for specific applications.