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Up Topic Welding Industry / Inspection & Qualification / WPS/PQR Qualify A-Number
- - By dhannaro (*) Date 06-09-2010 03:53
Hello,

Refer to QW-422 A- Number Classification of Ferrous Weld Metal Analysis for Procedure Qualification , I'm has review  exiting WPS/PQR material A 355 grade P11 ( P4 ) with selection welding rod  F-No.6 SFA-5.28  A No.4 ( Cr, 2.25) and mechanical test is acceptable , But this material A335 Gr P11 is 1.25 cr ( A No.3 ) for this case this WPS/PQR is validity ? Or we have to re-qualify with A no.3 Cr 1.25 ?

Thank you
D hannaro
Parent - By nantong (**) Date 06-09-2010 07:16
Don't see why you have to requalify but if you want to change to the 1.25%Cr consumable you will have to requalify.
- - By dhannaro (*) Date 06-09-2010 09:06
Our Client/ AWS CWI certified inspector reply to me, and he told that PQR of 2.1
/4Cr(A-4) is unable to cover 1.1/4Cr (A-3), and it shall be re-certify
Parent - - By js55 (*****) Date 06-09-2010 11:04
If you are going to change the filler from B3 to B2 you will most likely have to requalify.
However, its interesting, the A-No is the deposit. Chances are, at least in the root and hot pass, if welded with GTAW especially, you will actually have what is very close to an A-3 deposit with a B3 filler due to dilution. The Mo will be the problem at keeping you in A-4, not the Chrome. In the root the Chrome will fall into A-3.
Generally what happens is if you use a B3 filler you list an A-4 deposit but this does not represent reality.
The Chrome will most likely be in the A-3 range and the Mo will most likley be in the A-4 range and therefore the deposit as a whole is actually neither one. Or, at some point in the weld A-3, at some point above the root/hot its neither, and then towards the cap its A-4.
I have never fully understood the A-No system. I think it adds needless confusion. Dissimilars get messy with code compliance. I think it looks good on paper but is not representative of the weld deposit in many cases. Would you have to PMI every pass to actually be compliant with the code?
Perhaps Marty can help us out here.
But, as Nantong indicated, why do you have to change?
Parent - By n4v4rr0 (*) Date 06-10-2010 16:17
hi all,

according to QW-404.5, in ferrous metals a change in the chemical composition of the weld deposit from one A number to any other A number in table QW-442 is an essential variable. only qualification with A No. 1 shall qualify for A No. 2 and vice versa.

best regards

n4v4rr0
Parent - - By MBSims (****) Date 06-10-2010 22:25
Don't forget there are several ways allowed in QW-404.5 to determine A-Number.  For GTAW, SMAW or GMAW, most people seem to use the chemical composition from the filler metal specification or manufacturer's test reports, per (b) or (c).  Below are the different methods allowed.  My understanding of the A-Number concept is that it is a method of reducing the number of welding procedure qualifications required, the same as the use of P-Numbers is intended.  Otherwise, you might have to qualify any change in AWS classification.

From QW-404.5:

The weld metal chemical composition may be determined
by any of the following:

(a) For all welding processes — from the chemical
analysis of the weld deposit taken from the procedure
qualification test coupon.

(b) For SMAW, GTAW, and PAW—from the chemical
analysis of the weld deposit prepared according to
the filler metal specification, or from the chemical composition
as reported either in the filler metal specification or
the manufacturer’s or supplier’s certificate of compliance.

(c) For GMAW and EGW—from the chemical analysis
of the weld deposit prepared according to the filler
metal specification or the manufacturer’s or supplier’s
certificate of compliance when the shielding gas used
was the same as that used to weld the procedure qualification
test coupon.

(d) For SAW — from the chemical analysis of the
weld deposit prepared according to the filler metal specification
or the manufacturer’s or supplier’s certificate of
compliance when the flux used was the same as that used
to weld the procedure qualification test coupon.
In lieu of an A-Number designation, the nominal chemical
composition of the weld deposit shall be indicated
on the WPS and on the PQR. Designation of nominal
chemical composition may also be by reference to the
AWS classification (where such exists), the manufacturer’s
trade designation, or other established procurement
documents.
Parent - - By nantong (**) Date 06-11-2010 01:33
I am surprised no one has picked up on JS55's comments. Really really relevant.
Parent - By Shane Feder (****) Date 06-11-2010 03:08
Hi Nantong,
I was going to reply earlier but was concerned I may show my lack of metallurgical knowledge.
As far as I can see the OP is talking about two totally different things - an A4 Filler Metal (2.25% Cr) and a P4 base metal (1.25% Cr) and as the A numbers are for filler metal and not base metal then the A3 does not come into it.
I agree with your initial response, why requalify ?
As JS55 has stated, there may be a specific reason why a 2.25% Cr electrode was chosen to weld a 1.25% Cr base material.
Regards,
Shane
Up Topic Welding Industry / Inspection & Qualification / WPS/PQR Qualify A-Number

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