QUALIFICATION OF PQR WITH SR AS PER ASME SEC X 1

[NARESHSHAH]

Mfr. has qualified a Procedure as per ASME Sec IX Edition 2001 with addenda 2002 with the following conditions :

Thickness 28 mm SA 516 Gr.70, UTS required : Min. 480 MPa & Max : 620 MPa, with SR at 600 + / -10 degree Centigrade, Tested for Impact at Minus 50 degree centigrade, Preheat Temp 100 degree centigrade, Inter pass temp. Max 150 degree centigrade, Welding Process SAW. Used plates for this qualification is having actual UTS (Before SR) is 565 MPa & UTS after SR (tested value ) observed is 536 MPa.

Mfr. want to do the Welding with the use of above PQR within all essential parameters acceptable as per ASME Sec IX but UTS of Plates SA 516 Gr. 70 - 32 mm of actual job's is only 485 MPa. As per clause : UCS 67 d) of ASME Sec VIII Div.1, does not call for testing of Production Test Plates for UTS. Based on above experience we found the reduction in UTS by 4 to 5 % as compare to Original UTS of plates before SR. If we permit use of these plates having UTS of 485 MPa, actual UTS after SR may be reduced to 460-470 MPa assuming a reduction of 4-5% after SR as compares to original UTS.
Kindly suggest whether we can allow Mfr. to use these plates / PQR for actual job or not?

N. V. sHAH
Baroda, India

 

[sayee1]

Naresh,
1. What were the values of the tensile strength for the weld metal in the as welded and PWHT conditions?
2. What were the values of UTS obtained for the PQR after SR? Where was the break in specimen(in weld or outside weld)

Based on ASME section IX this procedure should be acceptable, but to see if the weld metal still has sufficient strength after PWHT to maintain integrity of joint, the above data would be required especially since there is no requirement of production test.This would help decide whther the weld metal/consumables ok for the joint though the WPS itself is meeting Section IX requirements and hence only based on section IX requirements, can be used for this application.

The base material itself as can be seen from your data would not meet the minimum required strength after PWHT. In that case the manufacturer according to me should carry out a production test even if not required by code.
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668

 

[NARESHSHAH]

Many thanks for your reply.

During testing sample test pieces were broken from parent metal.Hence their in no problem in quality of weld before & after SR as well as quality of consumables.
Only problem is of acceptability of parent metal with border acceptable value of UTS before SR.
Regards,
N. V. Shah

 

[GRoberts]

If you are loosing tensile strength due to SR after welding, could your SR temerature be too long &/or too close to the previous tempering temperature? What about reducing the time &/or temp of the PWHT?

 

[sayee1]

Roberts:
SA 516 Grade 70 : Plates 1.50 in and below are normally supplied in the as rolled condition. The plates may be NR or SR condition. When notch toughness tests are required on plates, 1 1/2 " and under, the plates may be norm,alized. If approved by purchaser, cooling rates faster than those by cooling in air are permissible for improving notch toughness provided the plates are subsequently tempered in the range 595 to 705 Degrees C. The plates would have been maximum normalized--- Naresh please confirm. However maybe the time is too long.
Naresh
Was the holding time 1 1/2 hrs max(1 hr/" is the norm if I remember right). Why the SR? Is it because of the material requirements as per ASME section VIII div1( If I remember correctly, PWHT is required for P 1 materials if the nominal thickness exceeds 1 1/2&quot or was it an intermediate step to help cold forming(like for froming of dished ends)
I again feel that the base material itself as can be seen from your data would not meet the minimum required strength after PWHT. In that case the manufacturer according to me should carry out a production test even if not required by code or be asked to change the material.
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668