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Up Topic Welding Industry / Technical Discussions / How to qualify SAW for 6-15mm (With CVN required)
- - By Bowler_Hat (**) Date 10-21-2015 14:11
Hey all,

I'm splitting hairs here and not sure where to go. Table 4.6 of D1.1:2010 (page 145) under the PQR Supplementary Essential Variable Changes for CVN Testing Applications Requiring WPS Requalification for SMAW, SAW, GMAW, FCAW, and GTAW

It reads "Minimum thickness qualified is T or 5/8 in [16mm] whichever is less, except if T is less than 1/4 in [6mm], then the minimum thickness qualified is 1/8 in [3mm].

So if I qualify a 27mm plate with a CVN, that covers me down to 16mm.

And, if I qualify a 5mm plate with CVN, that cover me down to 3mm.

So...how does one qualify the thicknesses between 6mm and 15mm?
Parent - By KBNY (**) Date 10-21-2015 16:36
The way I understand it...

If you do CVN testing on a 5mm plate, that will cover you for 3mm-10mm. If you did an additional CVN test on say 8mm plate, that would cover you for 8mm-16mm.
Parent - - By In Tension (**) Date 10-21-2015 22:56
Unfortunately, you have to qualify multiple test coupons to cover the full thickness range desired.  What's the thinnest base metal thickness you need to qualify?  Thickest?  If these are the same weldments you were describing in the "full-length tack" thread you'll also need to run coupons for GMAW.  If you already have PQRs available for non-CVN procedures, remember that you don't need to do redundant mechanical testing, assuming all variables stay the within their proper range.  This can save you time and money.
You're not the first inspector thrown for a loop when CVNs are invoked so don't get discouraged.  Economically and efficiently crafting a WPS is an art form that takes years to develop.  I still have a lot to learn myself and use the search function in this forum whenever I come across something new or unfamiliar.  It's very informative.
Parent - - By Bowler_Hat (**) Date 10-22-2015 11:53
At Current, the thinnest plate needed to be qualified is 10mm, and we hit every mm on the way up to 16mm.

I haven't found any documentation here (my work place)on specific tests referring to the GMAW process. Since that bit of the process is entirely remelted, it's individual inspection is only bound by visual....or so that's my thought at the current time.
Parent - - By In Tension (**) Date 10-22-2015 14:18
Regardless of the inspection requirements the procedure still needs to be qualified.
5.18.1 - Tack welds and construction aid welds shall be made with a qualified or prequalified WPS...
I think the consensus in the "continuous tack" thread was that who cares what it's called as long as it's qualified.  But it turns out that it isn't?  If CVN is specified then the WPS, by virtue of requiring mechanical testing, cannot be prequalified (and even if it were, it would still require a WPS).  It therefore requires a PQR and associated documentation.
Parent - - By Bowler_Hat (**) Date 10-22-2015 15:23
Hey In_Tension,

Your response there was confusing.

The customer is requesting CVN for all welds performed. I haven't mentioned trying to use prequalified measures in any of my posts (as our customers won't allow pre qaulified WPS).

With that, the question is like the owl and the center of a tootsie pop:

How many PQR's (requiring CVN) does it take to cover thickness of 6mm - 15mm?

Thanks!
Parent - - By In Tension (**) Date 10-22-2015 17:40
Sorry for the confusion. 
My point was simply that you need to consider the GMAW pass during the qualification process.  From the clause I referenced above it's clear that, whether it's a tack weld or a root pass, if you have no testing documentation for that process it is clearly not qualified.  The fact that it's completely remelted during subsequent SAW passes has no bearing on this fact.  So I think your jumping the gun with concerning yourself about the thickness if you haven't even considered the scope of what processes need to be qualified.  This can be a complex task and I recommend you slow down and delineate WHAT needs to be qualified before you concern yourself with HOW to go about doing it. 
Asking one-dimensional questions can land you in hot water because somebody may correctly answer your question but they don't have the whole story, and this may alter their answer.  For example, the answer to your tootsie pop question is... it depends how many welding processes you're using.  Two?
Parent - By Bowler_Hat (**) Date 10-22-2015 18:17
Thanks for the response.

From what I have here with this company, there are PQR's that qualified the GMAW process for 3mm to unlimited thickness of plate. From your comment, am I to conclude that when writing a WPS for a SAW process, one needs to submit two WPS? If so...that's not good news for this company here. They've been operating for years with just one PQR, to allow them a GMAW backing with SAW root, fill cap. I promise you, I'm not one to say "that's how it's been done...therefor it's the right way."

How would one note that in a WPS "See this WPS for the start of this weld?"

As for what needs to be qualified:

At current I'd like to find a PQR that will qualify the welding of 3mm-Unlimited thickness plate. All of these PQR's will require CVN, with that, I know if I tested a 27mm plate that qualifies me for 16mm - Unlimited, as well I know if I qualified a 1/4 in plate, that would cover me from 3mm to 5mm. But what about 6mm - 15mm, that's what I'm hoping to figure out.

The backing is GMAW, the root, fill and cap is SAW.

If I'm not providing the information you're looking for, could you objectify what additional information your seeking?
Up Topic Welding Industry / Technical Discussions / How to qualify SAW for 6-15mm (With CVN required)

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