WPS/PQR 1

[DCMV]

We are Going to be making some strength welds on a tube to tube sheet joint we have a calculated min weld size of .053" and max weld size of .168". We submitted a wps and PQR to client welding engineer and it was returned as rejected. The client stated that the PQR has a specified min weld size of .085" and max of .168" and the PQR should have the same min weld size as the engineer calculated for the specific tube to tube sheet being welded. I am kinda of confused, my thinking is that the if calculated min weld size is .053 max.168" and the PQR specifies .083 as min it would be accepted because we are above the min cal of .053. I could see if the situation was reversed with min cal at .083 and PQR min of .053 being rejected. Can someone help me understand the tube to tube sheet with strength weld calculated min/max weld size and the WPS/PQR required.

 

[gtaw]

It is difficult to provide you with a proper response without knowing what welding standard is invoked by the customer.

The PQR does not typically specify the range of qualification, only the thickness of the materials actually used to qualify the WPS.

Best regards - Al

 

[DCMV]

Asme sectIX and constructed to ASME sect VIII. I understand that the PQR is actual welded and based on actual the WPS will provide Range. We are required to provide preliminary PQR/WPS and mockup detail drawing prior to start of T/TS mockup. The detail drawing indicates tube T=.083" and D-.750" with min/max calculated weld size .053/.168, the PQR state min of .083" and max of .168. The client engineer rejected the preliminary PQR because the min weld size did not match that on the detail drawing. I was under the impression that the min calculated T to TS weld size was just that a minimum required so as long as a weld that size or greater (not exceeding the max) was acceptable.

 

[gtaw]

Without reading the actual project specification it is difficult to say exactly what your client is asking for.

I usually develop a preliminary WPS (PWPS)that defines how the WPS will be qualified. It is simply an unqualified WPS that provides the welder with all the information needed to secure the proper material of he correct thickness, how to prepare the joint to be welded, what welding process and filler metal will be used, what filler metal will be used, what welding parameters will be used, etc. The PWPS is developed after reviewing the production requirements to ensure the proper material thickness is used to cover production requirements, the filler metal is appropriate, etc.

Following the PWPS, the welder welds the test coupon. All the actual welding variables used are recorded along with the results of the test required to qualify the WPS that will be used in production. The information recorded is "actuals", not what the welder should have used.

Assuming the PQR passes all the required tests, a WPS to be used in production is developed. The ranges for the base metal thickness, weld sizes, etc. are based on the information recorded on the PQR. The ranges permitted by the WPS are defined in Section IX. In some cases more than one PQR is required to qualify the full range of base metal thicknesses required for production.

Best regards - Al

 

[DCMV]

I understand all the above comments my question is if the calculated min weld size is .053" and the PQR has a specified min weld size is .083" is that grounds to reject the prelimary PQR.

 

[metengr]

Section IX has very specific requirements for tube to tubesheet tests in QW-193. There are ten mock-up welds required that depict those actually used in production within the limtis of essential variables used in QW-288. The area of concern related to your client is probably QW-193.1.3. The PQR must contain the minimum weld size to establish the minimum leak path dimension required by design. If the minimum weld size is 0.053", this must be the size on the PQR as a minimum for tube to tubesheet welds.