QW-403.6 Minimum Base Metal Thickness Qualified and PQR Thickness Limits

[DonRoss]

Hi, I developed a P1 to P1 procedure using 1-1/2" thick coupon to qualify weld deposit thicknesses of 3/16" to 8" [5/8" to 8" with impacts as QW-403.6 permits] and a 3/16" thick coupon for 1/16" to 3/8" [3/32" to 3/8" with impacts as QW-403.6 permits]. To qualify this procedure for impacts I used two PQR's where impacts were performed on the 3/16" coupon only to qualify both coupons; as permitted by ASME Interpretation: IX-07-09.

It states...

Interpretation: IX-07-09
Subject: QW-401.3 and QW-403.6, Thickness Range Qualified for Impact Testing (2007 Edition)
Date Issued: May 1, 2008
File No: 08-576

Background: A welding procedure qualification was performed on a 1 in. (25 mm) thick test coupon. Tension and bend tests were performed on the 1 in. (25 mm) plate. A second welding procedure qualification was performed on a 0.24 in. (6 mm) plate and only impact testing was performed. All of the essential and supplementary essential variables remained the same except for the coupon thickness.

Question: May the above PQRs be used to support a WPS for materials requiring notch toughness with a qualified thickness range of 0.1875 in. (5 mm) to 2 in. (50 mm)?

Reply: Yes.

My question is, based on the thicknesses qualified from both coupons, thickness ranges for impacts are 3/32" to 3/8" and 5/8" to 8"; can we assume thickness ranges of 3/8" to 5/8" also qualified?

I appreciate your insight.

Regards,

Don

 

[metengr]

If you have the 2010 Edition/2011 addenda of Section IX look at QW-403.6. So, using the 1.5" coupon and running impacts qualifies down to 5/8" for impact because 5/8" is the lesser of 1.5". Now, you have a second coupon with impact that was 3/16" in thickness. Looking at QW-403.6 the minimum thickness qualified is 1/2 of 3/16" up to 2x3/16" (3/8"). You still have a gap between 3/8 to 5/8".

 

[DonRoss]

I appreciate the reply. The WPS/PQR's have been developed in accordance with 2001 Addenda.

So in essence, I'd have to qualify a 3/8" thk coupon with impacts to cover the range between 3/8" to 5/8", technically 3/4".

I'll keep this posted should I find any further clarification on the matter.

Thanks again,

Don

 

[metengr]

Don;
OR, you re-qualify a coupon following the same essential and supplementary essential welding variables as for the 1.5" thick coupon except the coupon thickness is 5/16", instead of your 3/16" thickness to bridge the gap.

 

[DonRoss]

Yes, that would be exact.

Great idea!

Thanks,

Don

 

[weldtek]

I respectfully disagree. In the situation described in the original post, the Code does not limit max thickness for impact qualification rather it limits minimum thickness. As pointed out, an impact tested coupon having a thickness of 5/8" or thicker is limited to 5/8" minimum thickness qualified. The rationale being that heat input can degrade notch toughness and 5/8" is considered the lower limit where cooling takes place in three directions. Thinner sections cool more slowly and therefore must be qualified for impacts separately.

That's why the interpretation shown above says the answer is yes to the query;
'Question: May the above PQRs be used to support a WPS for materials requiring notch toughness with a qualified thickness range of 0.1875 in. (5 mm) to 2 in. (50 mm)?' Note there is no gap in qualification between 3/16" and 2".

This position is also supported by Interpretation IX89-100R

 

[metengr]

weldtek;
Thinner sections require fewer weld passes which does not afford the possibility of grain refinement for improved notch toughness behavior as with multiple pass welds in thicker sections. This is why a separate impact qualification is required for thinner sections, and focuses on minumum coupon thickness. After review of interpretation IX89-100R I do agree with your position. I have run into this situation with welding code experts that have argued impact qualification thickness follows the 2T limit as for mechanicals.

 

[metengr]

Also, Section IX does not specifically state upper limit thickness impact requirements because it only deals with how to qualify weld procedures with impacts. If impact testing is mandated by a code of construction or engineering specification upper limit thickness may be dictated by the respective construction code, such as B31.3 or by an engineering specification.

 

[weldtek]

metengr,
I appreciate your insight and agree that customer requirements may be more stringent. I recently encountered a situation where our customer acknowledged that our procedure, which was qualified in line with the scenario described above, met Code requirements, but they insisted we qualify an additional PQR to 'bridge the gap'. I want to point out though that they paid for the additional testing. That's the way it must be. Customers can ask for anything, but they must do so at the quote stage, not after the fact.

 

[Kiwi2671]

metengr / weldtek,
Purely out of curiosity - why would the minimum thickness be 5 mm (presumably as per QW 451.1) and not 6 mm as per QW 403.6 (thickness of test coupon) ?
Would notch toughness requirements not take precedence over QW 451.1 ?
Regards,
Kiwi

 

[weldtek]

QW403.6 allows for qualification at 1/2 T where coupon T < 1/4".

 

[metengr]

Kiwi2671;
In the case where a welding procedure is qualified either with or without impact testing the base metal range for use would be 5mm minimum per QW 451.1 for the applicable coupon thickness. The mechanicals still drive the procedure qualification and impact testing and thickness ranges go along for the ride (if required).

 

[DonRoss]

Hi, could you one of you gents post Interpretation IX89-100R please?

Thanks,

 

[Kiwi2671]

Hi Don,
Here you go

Interpretation: IX-89-100
Subject:
Date Issued: January 2, 1991
Section IX, QW-202'2 and QW-451
File: BC90-663
Question: A procedure qualification in a test coupon of 1-1/2 in. thickness has been qualified
to the requirements of QW-202.2(a) with the exception of notch toughness. A second Procedure
Qualification with identical essential and siipplementary essential variables, is tested for notch toughness
only, in a test coupon of 3/16 in. thickness. Do the above two Procedure Qualifications support
a WPS to weld a butt joint 3/16 in. to 8 in. in thickness where notch toughness in required?
Reply: Yes.

Regards,
Kiwi

 

[DonRoss]

Thanks Kiwi,

So then pressumably, as 403.6 permits, the limits shall be 3/32" to 8". This answers my question as I have done the same...
We can assume then the gap between 3/8" to 5/8" is qualified.

Thanks,

Don