Questions on welding procedure qualification with impact test requirem

[sw007]

Hi all,

I am reviewing one WPS which is supported by 3 PQR’s and was confused by the vendor’s documents. Impact test is required for the Welding Procedure qualification (Design temperature of vessel is -46 DegC).

WPS (SMAW):
Base metal: P1 Gr.1/2 to P1 Gr.1/2
Base metal Thickness range: 3/16” – 2”

PQR-1 (SMAW):
Base metal: P1 Gr.1 to P1 Gr. 1
Test coupon thickness: 1”
Tensile test, bend test, but no impact test

PQR-2 (SMAW):
Base metal: P1 Gr.2 to P1 Gr.2
Test coupon thickness: 0.24”
Impact test, but no tensile test and bend test

PQR-3 (SMAW):
Base metal: P1 Gr.1 to P1 Gr.1
Test coupon thickness: 0.24”
Impact test, but no tensile test and bend test

My question:
(1) Can these PQR’s support Gr1/2 to Gr1/2 welding at the specified thickness range? To my understanding, Gr.1/2 are only qualified by the thickness from 3/16-0.48” by PQR-2 & 3.

(2) Can we use the combination of PQR-1 (No impact test), PQR-2 & 3 (No tensile and bend) to support the WPS, assume the other parameters are ok.


Please help me.

Thanks.

 

[metengr]

If this is for ASME Section VIII, Div 1, the answers are

(1) impact qalification for Groups 1 and 2 for P-No 1 base material from 3/16" to 2T.

(2) Yes, for the WPS.

 

[GRoberts]

Usually, materials thinner than 5/8" are exempt from impact testing by ASME design codes. What code is requiring the impact testing?

 

[metengr]

The impact exemption for Section VIII, Div 1 material is 0.394" or less, not 5/8". Also, above 0,394” thickness impact exemption depends on the minimum design metal temperature regarding impact exemptions.

 

[sw007]

vessel fabrication code is ASME VIII DIV.1.

Response to (1): Normaly, if impact test required, thickness range by PQR-1 is 5/8"-2" (3/16"-2" without impact requirement); Thickness range by PQR-2/3: 0.12"-0.48";

If we conbine these PQR's, then the qualified range is 3/16"-0.48". Thickness range from 0.48"-2" is not qualified because no impact results in PQR-1, If I am wrong, please correct me.


Response to (2) Similar to question 1, PQR-1 has tensile and bend test, but no impact test. How can it support the WPS with impact test requirement from thickness range 0.48"-2".

Thanks again.

 

[metengr]

First, you need to review ASME Boiler and Pressure Vessel Code Section IX.

 

[sw007]

Megengr,

Thanks for you response.

The fabrication code is ASME VIII. The welding procedure qualification shall be in accordance with ASME IX. What I mentioned in this thread is based on ASME IX.

 

[metengr]

sw007;
Ok, I see that you have reviewed Section IX. I went back and double checked your PQR variables. Since 0.24" is less than 1/4", QW-403.6 requires the minimum qualification thickness as 1/2T (coupon thickness), 0.12" minimum. Are you sure this thickness is 0.24" or is it close 0.250" to simplify this process?

Anyway, using Table QW-451, the minimum thickness for qualification based on a coupon thickness of 1" is 3/16" for bends and tensile testing.

A WPS that is supported by multiple PQR's must have essential and supplementary essential variables within stated ranges (see Article II). In this case, the 3/16" min would be required for this WPS qualified for impact because your PQR that is for bends and tensile has this as a minimum range (despite the impact qualification allowing a minimum base metal thickness of 0.12").

So, as I stated above the minimum base metal thickness is 3/16” for impact IF multiple PQR’s are used for this WPS.

 

[sw007]

Metengr,

Thanks for your time.

It looks like the thickness of 0.24" is used to simplify the process.

Actually I understand why the vendor speicfy 3/16" as the minimum, just like you mentioned above.

My concern is the maximum thickness range. Impact test is performed only on PQR-2/3, which support the thickness range from 3/16" to 0.48". Thickness range 0.48"-2" is only supported by bend test and tensile test, but not impact test.

 

[GRoberts]

I believe that the answer you are looking for is in QW-401.3. The PQR with tensiles and bends contains all the essential varaibles. Since QW-403.6 doesn't limit the maximum thickness for additional PQRs qualifying supplementary essential variables per QW-401.3, it sounds like the presented PQRs do cover the qualified range listed on the WPS.

 

[sw007]

GRoberts:

QW-401.3 (the second paragraph of this section) indicates that additional test coupon should use the same procedure and same essential variable. It means that the addition test coupon thickness is the same as the orginal test coupon thickness.

Probably this is the reason why the forth paragraph of QW-401.3 mentions that no limit the maximum thickness is applied.

If I am wrong, please correct me.

 

[metengr]

Correct.

 

[GRoberts]

SW007,
You are right that the same essential variables need to be used. Since the first WPS qualifies 3/16" to 2", and the other PQRs are .24", they are within the essential variable range as the first PQR. Since QW-403.6 doesn't affect the maximum thickness, the .48" limit that would be imposed had the .24" PQRs been the only ones does not apply, and the procedure should be qualified for impacts from 3/16" to 2".