max hardness after PWHT of P4 & P15E matl?
max hardness after PWHT of P4 & P15E matl?
(OP)
Could you help me on where to find the max hardness value after post weld heat treatment of P4 & P15E materials.
the construction codes are either B31.1 or ASME sec 8, we have done a welding procedure qualification test and we got some hardness values, but do not know whether the hardness readings taken are acceptable.
there is a brinell hardness max in table 331.1.1 of B31.3 but could not find it in either B31.1 or ASME sec 8
Thank you in advance for any assistance or guidance
the construction codes are either B31.1 or ASME sec 8, we have done a welding procedure qualification test and we got some hardness values, but do not know whether the hardness readings taken are acceptable.
there is a brinell hardness max in table 331.1.1 of B31.3 but could not find it in either B31.1 or ASME sec 8
Thank you in advance for any assistance or guidance





RE: max hardness after PWHT of P4 & P15E matl?
EPRI, in its 2011 publication, recommends a maximum hardness of 280 BHN for P91 to P91 welds using "B9" filler - the same can be applied to P4-P15E using "B9" filler. Additional PWHT should be performed if hardness excceds 280 BHN. The desired range is 190 BHN to 250 BHN after all welding & PWHT has been performed. When welding with a "B3" filler metal the 250 BHN max should be considered.
RE: max hardness after PWHT of P4 & P15E matl?
The EPRI document which is a guideline for fabrication of CSEF steels and mentioned by stanweld should be used as a guide only. It was developed based on a tailored colaberation project and it was decided to make it public to promote safety with use of CSEF steels.
RE: max hardness after PWHT of P4 & P15E matl?
Based on extensive microscopy and mechanical testing, low hardness in P91 base materials and weld is believed more likely to lead to premature failure in service. We have seen P91 materials improperly heat treated with very high hardness (> 380 BHN) fail hydrotest due to stress corrosion cracking.
RE: max hardness after PWHT of P4 & P15E matl?
P15E - E9018-B3
It is a pipe attached to pressure vessel and the connecting pipe is under B31.1
The thk of 6" pipe we used during procedure qualification test was 11mm.
Heat was brought up to 730deg C with soaking period of 1hr as per B31.1 / sec VIII.
If you refer to B31.3, the soaking period for this material is 2hr min.
The max BHN obtained is 290 at HAZ. Do you think the 1hr soaking period as applied is not enough?
Thank you,
Robert
RE: max hardness after PWHT of P4 & P15E matl?
RE: max hardness after PWHT of P4 & P15E matl?
RE: max hardness after PWHT of P4 & P15E matl?
objective: weld zone hadrness < 270 Hv
LMP=21= T*(20+log(t)) /1000
T= holding temperature, K
t= holdng time, hrs
LMP= larson miller parameter for PWHT tempering
some rough values for a LMP=21 are:
1400 F for 2 hrs 10 min
1375 F for 4 hrs
1350 F for 7hrs 40 min
some other minor points voiced lately are:
-must add thermocouples directly under heating coil to avoid overheat of metal directly under coil. The amount of overheat that occurs directly under the center of coil mass is roughly proportional to the temperature ramp rate times the square of distance from the center of the coil to the weld zone monitoring thermocouples. Some data shows this can be more than 100F over the weld zone , if the istance is alrge or the ramp rate is excessive. Exceeding 1470 F can occur if your not careful
- Siemens claims that repair welds must be PWHT'd about 25F below the original weld's PWHT holding tep, but others claim this is hogwash and not relevant to P91
RE: max hardness after PWHT of P4 & P15E matl?
I agree the problems really begin when the rubber hits the road - the capability of the constructor and the difficulties of field hardness testing.
stanweld,
What is the number of that 2011 EPRI document?
RE: max hardness after PWHT of P4 & P15E matl?