Increase of Min. Preheat temperature ASME IX

[ElCidCampeador]

Hi there, I have a PQR for GTAW + GMAW processes, no impact test required.
In this PQR the minimum preheat temperature is set to 50°C.
Could I use it as support for a WPS GTAW+GMAW with minimum preheat temperature=100°C?
Increasing of min. preheat temperature appears in table QW-255/256 neither in essential nor supplemental variables. What does this mean? Does it mean that in the WPS I could increase this temperature whatever I want? thanks

 

[metengr]

Yes, you can increase preheat temperature without re-qualification because preheat is considered beneficial in welding. Decreasing preheat from that qualified is another matter.

 

[SectionIX]

The only caveat is that if you decide to increase the preheat, or any other non essential variable, you need to amend the WPS; requalification is not necessary for non-essential variable changes.


ASME IX, QW 200.1(c)

(c) Changes to the WPS. Changes may be made in the
nonessential variables of a WPS to suit production requirements
without requalification provided such
changes are documented with respect to the essential,
nonessential, and, when required, supplementary essential
variables for each process. This may be by amendment
to the WPS or by use of a new WPS.

Changes in essential or supplementary essential (when
required) variables require requalification of the WPS
(new or additional PQRs to support the change in essential
or supplementary essential variables).