If you are working to ASME Section IX, one can qualify the WPS by welding a sample that includes GTAW root and second layer, followed by completing the coupon with a different welding process. The WPS will be qualified for the full thickness, assuming both processes are used in production, or two separate WPSs can be generated, one for GTAW and a second for the other welding process. The thickness range qualified for GTAW is based on the thickness deposited and recorded on the PQR. Likewise, the thickness range of the second WPS would be dependent on the thickness deposited with the second welding process and recorded on the PQR.

If the thickness deposited with each welding process is not recorded on the PQR, the PQR and the subsequent WPS that are based on the PQR are not valid. The same holds true if filler metals from different F number groups were used to weld the qualification assembly. For instance, if the root bead is deposited using an E6010 electrode (F3) and the remaining is welded using E7018 (F4), the thickness deposited for each F number must be recorded for the PQR to be valid.

That brings us to an interesting problem. Section IX does not include a requirement to record who witnessed the welding of the test assembly. Yet, many contractors wisely record nonessential variables such as arc voltage, welding current, travel speed, etc. When asked who witnessed the welding and recorded the welding parameters, they respond, "The welder records that information when he welded the coupon."

At that point I usually say something to the effect, "That welder has to be some welder if he can watch the weld pool and the machine at the same time. Possibly he has an extra set of eyes in the back of his head!"

The point being, any information recorded on the PQR must be factual and accurate. One cannot fill in the blanks at a later time. To do so invalidates the PQR, the WPS, any welder qualifications that were performed using that WPS, and any production welding completed using the invalid WPS. That is a very expensive mistake for everyone, contractor and customer alike.

Best regards - Al