ASTM A352 LCB and LCC

[amirparviz]

Dear All,

Could somebody help me to undrestanding what is differences between Casting valve material ASTM A352 LCB and A352 LCC,
we request in our material requsition for casting valve body in Low Temperature ASTM A352 LCB while Vendor quotation offer ASTM A352 LCC, I realy could not find a rational reason for accepting or rejection?
Does anybody knows?

 

[metengr]

The difference between these two Grades is the LCC is a C-Mn steel, while the LCB is a carbon steel. This difference results in the LCC Grade having slightly higher tensile and yield strength requirements. The minimum impact testing requirement is -50 deg F for both Grades. So, I would agree with you.

 

[GRoberts]

The specifications overlap enough, that much of the materail can be certified to both specifications. The LCC has a higher yeild strength, and higher energy requirements on the CVNs. Unless you have an objection to the higher strength, LCC would not have a problem filling in for LCB.

 

[amirparviz]

metengr,

As I know the size of allowable flaw is propotional K/(yeild)^2 and I think this might be problem in QA/QC besides the required energy for impact testing for LCC is slighly more than LCB in -29 C (20 instead 18).
What do you think?

 

[FIF99]

Hi,

We allways specify LCC to meet identical pressure/Temperature ratings (ASME B16.5) as for equavalent LF2 Cl.1 flange material.
LCB do have lower p/T limits than LF2.

Regards,
FKE

 

[metengr]

amirparviz;
IMO the differences are not that significant as GRoberts points out. Despite the slight increase in YS, the notch toughness requirement is increased so I don't really see a problem regarding substitution.

 

[FIF99]

Hi,
Reason for rejection could, as far as I can see, only be the maximum design pressure of the pipe class, which is lower for LCB than LCC/LF2.
Is the valve API-6D, or API 602 or ASME B16.34?
In there are tables presented showing the maximum p/T limits per valve body material. These should fall within your limits of the applicable process design conditions (pipe class).
Regards,
FKE

 

[metengr]

FKE;
Good point. However, in most service applications for valves the working pressures for a specific service temperature are normally well below the values in ASME B16.34 Table 2-1.2 and 2-1.3.