[MW:17306] PWHT for P15E to P3
Binoy Soman
Dear experts,
Kindly explain about PWHT requirement while welding two materials among which one require PWHT by code and other does not (Eg; P15E to P3 materials).
What should be the cycle that must be followed, Is it the same that of P 15E to P 15E?. Considering the lower critical temperature of P3 material , I select 700-730°C temperature range for PWHT of P15E to P3 (correct me if I am wrong).
P15E to P15E PWHT cycle that we are following is attached.
S.Binoy
Prakash Hegde
Dear Mr Binoy
i) As per ASME code P3 Gr 1,2 does not require PWHT if its thk is less than 16mm and For Gr3 It is manadatory for any thk and temp is min 593 C
ii) For P15E (P91) the PWHt is mandatory at 730C
Now if the weld joint P15E to P3 undergoesPWHT at 730C temp It will be afftecting the mechanical properties of P3 ( C% 0.5 Mo)
Therefore My openion is Better butter the weld edge of P15E with suitable P91 filler and
conduct the PWHT of P15E (P91)as per code at 730C and later on weld that edge with P3 (C % 0.5Mo) consumable and that joint need not be PWHT if it is P3 Gr1 or 2 In this case re is no deteoriation of P3 properties
However PQR require to be qualified with above condition
Regards
Hegde
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Binoy Soman
Thanks Hedge,
Buttering shall be with P91 filler? If so, kindly explain the basic technical reason.
S.Binoy
kannayeram gnanapandithan
John Henning
I am not sure what Code you are working to. ASME Section I, Section VIII, and B31.1 would all allow heat treatment of joint you suggest at a minimum temperature of 705°C (1300°F) if the filler metal had less than 3%Cr, was nickel based, or austenitic*. The maximum temperature would determined by lower critical temperature for the P3 material (approximately 730°C (1350°F) per B31.1 Table 129.3.1). This would give you a fairly narrow window of 705°C to 730°C. I believe the rational is that the permissible operating temperature for the P3 material is low enough that there is no challenge to the 91 material (i.e. well below the creep range for P15E).
However, in general I would recommend welding in a pup piece of either P5a or P4, heat treat according to the requirements of P15E. Then the P3 material would be welded to the pup piece and heat treated to the requirements of the pup piece material.
*See:
Section VIII, Div. 1, UCS 56 Note 2 to P15E
See Section I, PW-39-5 Note 2
See B31.1 Table 132 Note 2 to P15E
Hope this helps.
John A. Henning
Welding & Materials
From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Binoy Soman
Sent: Monday, April 08, 2013 3:15 AM
To: material...@googlegroups.com
Subject: [MW:17309] PWHT for P15E to P3
Dear experts,
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Prakash Hegde
Sorry Buttering should be of P3 material i.e. 80SD2 on P91 say thk of 6mm
However PQR to be qualified accordingly i.e
If Carried on Pipe then On P91 pipe at the weld edge butter by P3 material
ii) This buttered pipe to be PWHT at 730 same as on the job
iii) Weld a same PQR coupon i.e One pipe of P91 with buttered and PWHT at 730 and second pipe of P3 material and Joint the same with P3 Filler
This coupon of PQR to be tested w/o PWHT
This will satisfy your all condition
Regards
Hegde
Hegde |
kannayeram gnanapandithan
ASME Sec 1, PW39 P15e Note 2, if Filler metal chromium content is less than 3%