Wednesday, January 9, 2013

Re: [MW:16482] RE: 16466] Effect of Higher temp PWHT but below AC1 for PQR

Dear Mr Goswami
Thanks for clarification which I agree that  we require to qualify fresh PQR (Having Impact test ) for cahnge in soaking temp. range ( e.g. If you have qualified PQR of temp range say 600-620 C you require to requalify fresh  PQR  for temp range 630-650C  to satisfy clause of QW407.2) hence temperature range of PWHT temp is also very important factor when PQR is qualified for Impact test
Once again Thanks for clarification
Regards
Hegde P.B.

From: pgoswami <pgoswami@quickclic.net>
To: materials-welding@googlegroups.com
Cc: pb.hegde@yahoo.com
Sent: Wednesday, 9 January 2013 8:24 AM
Subject: [MW:16470] RE: 16466] Effect of Higher temp PWHT but below AC1 for PQR

Mr. Hegde,
 
A change of PWHT (T& T) is a supplementary essential variable. As the PQR was qualified with Charpy Impact and if the same impact requirement applies to the equipment, a change of PWHT  temperature to 650-670 Deg C would call for new Procedure Qualification to be done.
 
For SA 516 Gr70 steel PWHT at elevated temperature can significantly reduce tensile as well as impact properties.In the attached file look at Fig-6 for effect of PWHT on tensile properties, while Fig- 8  & 9 are for impact properties. Note these values may differ from plate to plate , heat to heat. As SA 516/70 doesn't contain any alloying elements e.g Cr or Mo, fall in tensile and impact values could be significant.
 
May I ask why PWHT at higher temperature is thought of ? To control hardness ?? If there is such requirement, extending the soak time @ 600-620C  could be one option. The other option could be increase of PWHT temperature to 62--640 Deg C maximum. But certainly 650-670 Deg C would way above the PWHT limits of SA 516/70 steel.
 
In spite of the facts if  650-670 Deg C is thought of , qualify a PQR.
 
If you get hold of this ASME document, I'm sure there would be more  advices on this issue.
 
Thanks.
 
Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario , Canada .
 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Prakash Hegde
Sent: Tuesday, January 08, 2013 2:16 AM
To: materials-welding@googlegroups.com
Subject: [MW:16466] Effect of Higher temp PWHT but below AC1 for PQR

Dear Friends
 
I have a query
A)
I have qualified the PQR with Suplimentary Essential (Due to Impact test requirement) 
a)The base material is SA516 Gr 70 Thk-40mm
b)Process-SMAW
c)PWHT as per USC56  Actual PWHT cycle followed 600-620C Soaking temp with soaking time of 3hrs and 30min
d) Satisfied all essential variables including PWHT clauses
e)Impact tested at minus 30C
f)All test are satisfactory as per ASME sec IX
 
Now my querry is can I use above  PQR for making WPS for welding 190mm thk SA516 Gr70 material  with PWHT at 650-670C for 3hrs (As it is below transformation Temp AC1)
 
If you say yes then what is the effect of Higher temp PWHT  on mechanical properties of  SA516 Gr70 even though it is below AC1)
 
(As this PQR is not accpted by Client consultant for WPS welding 100thk material having PWHT temp 650-670C)
asThere is possiblity /references of detoriating the UTS at higher temp PWHT  e.g.As per LM parameter PWHT at660 C for 3 hrs is equivalent  to at  620c for 24 hrs )
Regards
 
Hegde P.B.
 
 
 
 
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