several WPSs and one PQR

By happy1 Date 02-08-2010 22:09

This is my first attempt at writing weld procedures so this may be a stupid question. I have several joints that I have written WPSs on(single V /single bevel /etc). I am welding the root or backing pass with pulse and metal core wire and then later on down the line we are welding the rest of the groove up with solid wire. Because of the two different processes I have to do a PQR on these joints. My question is will one PQR cover several WPSs if they are similar type joints ? I have asked two CWIs and gotten two different answers.

By jwright650 (*****)

Date 02-08-2010 22:39 Edited 02-09-2010 14:26

happy1,
If this is WPS is going to be written to D1.1, GMAW and MCAW are considered the same process. They lump solid wire and metal core wire together as the same process.

edit: AWS A5.18 This specification prescribes the requirements for classification of solid carbon steel electrodes and rods, composite stranded carbon steel electrodes, and composite metal cored carbon steel electrodes for gas shielded arc welding.

The part that makes your WPS need qualifying is the pulsed power supply. Pulsing is considered short circuit mode, which is not prequalified(given the info supplied thus far). Gas mixtures that don't allow the solid wire to get into a spray mode are something else that can keep you from using a prequalified WPS, but you didn't mention anything about that.

By Lawrence (*****)

Date 02-09-2010 18:04 Edited 02-09-2010 18:07

Just for the sake of being as accurate as possible.

GMAWP (Pulsed Spray Transfer) is not considered a short circuit mode.

The limiting factor for D1.1 Prequalification of GMAW is Clause 3.2.4. This clause limits power supplies for GMAW and FCAW to constant voltage only. The great majority of GMAWP power supplies are CC/CV hybred types, showing a nature of both constant current and constant voltage during the cycle of the pulsed arc.

Below are some examples "Pulsed Short Circuiting Transfer" processes.
STT (Lincoln Electric's Surface Tension Transfer)
RMD (Miller Electric's Version of STT)
CMT (Feronius pulsed short circuit)

These would also require PQR's by virtue of limitations set forth in clause 3.2.1

By jwright650 (*****)

Date 02-09-2010 18:45

Thanks Lar for adding the clarification and the foot note.

By HgTX

Date 02-09-2010 17:01

It depends on just how different the WPSs are. Look at the essential variables tables in D1.1 (or whatever code you're working to). If you can find PQR parameters such that both the WPSs are within the limits, you're fine.

Hg

By happy1 Date 02-09-2010 19:06

Thanks for all who answered. I think I am on the right track now.