This is not as complex as it seems at first glance. I will address only ASME Section IX – if you need information on how EN/ISO documents handle this issue, I will defer to someone who lives and breathes those Codes as they are not my native expertise.
When combining PQR’s on a WPS you have to consider both weld metal thickness range and base metal thickness range qualified. Generally, the maximum base metal thickness range qualified for a combined WPS will be the minimum range from any of the PQRs as determined by QW-451.1. (note that I have problems with the english-to-metric conversions as I am uncertain where to apply exact vs. practical per ASME)
For example; say you have
PQR 1 – 0.375” (9.5mm) base metal thickness welded completely with GTAW and
PQR 2 - 1” (22.5mm) welded completely with SAW.
Each would qualify individually,
WPS 1 with a qualified base metal range from 1/16” (1.5mm) to ¾” (19mm) and GTAW maximum deposit of 19mm.
WPS 2 with a qualified base metal range of 3/16” (5mm) to 2” (45mm) and a maximum SAW deposit thickness of 2” (45mm).
When combining these two PQR’s into a single WPS, you can see that GTAW is only qualified on base metal thickness less than ¾” (19mm) and SAW is only qualified on thicknesses greater than 3/16” (5mm). So the combined WPS is only qualified for welding on base metal of 3/16” ~ ¾” (5mm ~ 19mm) and either process may be used to make a deposit up the maximum thickness of ¾” (19mm).
Now, say PQR 1* was performed on 0.375” (9.5mm) thick plate but the GTAW deposit was only 3/16” (5mm) with remainder SMAW
Then PQR1* supports WPS1* with base metal thickness range of 1/16” (1.5mm) to ¾” (19mm) but now with a maximum GTAW deposit of 0.375” (10mm)
Thus the combined WPS* would have the same qualified base metal thickness range, 3/16” ~ ¾” (5mm ~ 19mm), but the maximum GTAW deposit thickness qualified is 0.375” (10mm) while SAW could be used to deposit weld metal up to the maximum of ¾” (19mm).
So far no problem, eh?
Now the Section IX provides an exception, QW-200.4 (b). When the PQR base metal thickness is equal to or greater than ½” (13mm) and one of the listed processes is used for the root passes, then the PQR may be combined with any thicker qualified PQR and the root process will be qualified to 2t on that combined WPS.
Similar to the above, assume that PQR 1 was qualified on ½” (13mm) plate and the GTAW deposit was only 3/16” (5mm) with remainder SMAW
PQR 2 is as above.
Then, the combined WPS will have qualified base metal thickness range of 3/16” (5mm) to 2” (45mm) , with maximum GTAW deposit thickness of 3/8” (10mm) and SAW deposit qualified up to the maximum of 2” (45mm)
There are additional restrictions if GMAW in the short circuiting mode is used for the root process, but you can look at QW-200.4(b) and determine the result for yourself.
Let me know if you have additional questions.
John A. Henning
Welding & Materials
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of suresh venkat
Sent: Monday, December 26, 2011 7:17 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:13315] RE: 13196] combination of PQR with multiple process
Thanks Jhon,
I read yr previous post explaining the critria for combination of PQR with single process.
Can u please throw some light on combination of PQR's with multiples processes.
Suresh
On Mon, Dec 12, 2011 at 10:59 PM, John Henning <jhenning@deltak.com> wrote:
No.
QW-451 limits must be applied. QW-200.4(b) does not apply because Essential Variable QW-404.23 for root pass is different for PQR1 than PQRs 2 and 3. If you try and apply PQR 1, you are limited to base metal thickness of 1.5mm ~ 11mm thus if you combine PQRs 1 , 2, and 3 your base metal thickness range is 1.5mm ~ 11mm with maximum deposit thicknesses of 5mm for FCGTAW, 7.5mm GTAW, and 11mm for SMAW (BM > 5mm).
John A. Henning
Welding & Materials
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of suresh venkat
Sent: Monday, December 12, 2011 4:45 AM
To: materials-welding@googlegroups.com
Subject: [MW:13196] combination of PQR with multiple process
Dear all,
want to make a WPS combining following PQR's
Material - SS 316L
PQR 1 - full GTAW - T - 5.5 mm thk ( FCGTAW - 2.5mm + GTAW - 3mm)
PQR 2 - GTAW + SMAW - T - 12.7mm thk ( GTAW - 3.7mm + SMAW - 9mm)
PQR 3 - GTAW + SMAW - T - 31.75mm thk ( GTAW - 3.75mm + SMAW - 30mm)
PQR 1 is being used to avoid backing gas for root pass.
Doubt is whether the WPS is qualified base metal thk range - 1.5mm to 63.5mm as per QW 200.4a
Regards
Suresh
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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