A-216 WCB X A-352 LCB - cryogenics?

[gande]

Good afternoon,

I have doubts with steel ASTM A216 WCB and ASTM A352 LCB.

I need to select the material for a valve with the following conditions:

Fluid: Liquefied Petroleum Gas
Temperature: -45 ° C - Cryogenics
Class: 150 #
Diam.: 20 "

The ASTM recommends A216 to the low temperatures and A352 high temperature.

WCB and LCB - They have the elements alloys:

WCB and LCB:

C-0,3 Mn-1 Si-0,6 P-0,04 S-0,045 Cr-0,5 Ni-0,5 Mo-0,2 Cu-0,3 V-0,03

Why ASTM does not recommend the A216 WCB to low temperatures?

Could use the WCB to a temperature of -45 ° C?

Tanks!

 

[arunmrao]

Quite often if the test bar for LCB fails in impact,the part is accepted as WCB and the matter rests.

However,the heat treatment for LCB involves a double tempering cycle,whilst for WCB it is commonly Normalize.

For LCB grades small additions of Ni,and Mo is done,while for WCB grades it is not done.

Learn the rules,so you know how to break them properly.
Dalai Lama

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[rneill]

You should consult the design code in use which in this case is probably B31.3. B31.3 would not permit the WCB material to -45 but does permit the LCB material at these temperatures.

Note that according to B16.34 and B16.5, a LCB flange has a slightly lower pressure rating than a comparable flange from Materials Group 1.1 so in fact depending on what pressure rating you require, you may want to look at A352-LCC material which comes from a different materials group and has higher pressure ratings.