ASTM 335 P11 and P12 : differences?
ASTM 335 P11 and P12 : differences?
(OP)
What is the difference between the properties of P11 (1 1/4 Cr 1/2 Mo) and P12 (1 Cr 1/2 Mo) steels? In what applications would one be preferrential to the other?
As far as I can gather, apart from the Chromium discrepancy, there are very few differences in composition (I think the silicon range was different in both). P11 is roughly equivalent to BS 3604 621 while P12 is equivalent to 622.
Also of some interest is that the corresponding ISO standard (2604) grade TS 32 is equivalent to P12, although there is no equivalent ISO grade for P11.
Would anyone care to offer an explanation?
Regards
As far as I can gather, apart from the Chromium discrepancy, there are very few differences in composition (I think the silicon range was different in both). P11 is roughly equivalent to BS 3604 621 while P12 is equivalent to 622.
Also of some interest is that the corresponding ISO standard (2604) grade TS 32 is equivalent to P12, although there is no equivalent ISO grade for P11.
Would anyone care to offer an explanation?
Regards





RE: ASTM 335 P11 and P12 : differences?
For P12 @ 700 deg F, the allowable stress is 15.8 Ksi
P11 @ 700 deg F, the allowable stress is 15.5 Ksi
For P12 @ 1000 deg F, the allowable stress is 7.2 Ksi
P11 @ 1000 deg F, the allowable stress is 6.3 Ksi
My take on the other difference is that the increase in chromium for P11, gives a slight edge in terms of scaling/oxidation resistance. The molybdenum is what gives both alloys increased strength at elevated temperature.
RE: ASTM 335 P11 and P12 : differences?
RE: ASTM 335 P11 and P12 : differences?
RE: ASTM 335 P11 and P12 : differences?
RE: ASTM 335 P11 and P12 : differences?
RE: ASTM 335 P11 and P12 : differences?
We have had some P12 piping associated with steam turbines manufactured by Siemens and Alstom (European supplied).
RE: ASTM 335 P11 and P12 : differences?
Don't be surprised at either.