Selecting between 2 WPS based on thickness (AWS D1.1)

[willysatch]

Hello everyone,
There is a rule that if we run 2 identical WPS with different thickness, then WPS with thinner thickness should be chosen.
Is this correct? Does it have basis on AWS D1.1? Or is it just common sense? Thanks.

 

[gtaw]

I'm not sure I understand what you are asking. If you have two qualified WPSs, you more than likely have two PQRs to support the ranges listed by the WPSs. There are those who believe the WPS should be specific to the production requirement and there are those folks that believe the WPSs should cover a wide range of base metals, thicknesses, etc. My thoughts are if the manufacturer is building widgets that are all the same and the quantity is "high", a WPS specific to that widget is easily justified. If the manufacturer production requirements are varied and the quantities are low (think job shop), a WPS that encompasses a wider range of thicknesses and several groove types and fillets can be more useful to the welders.

In your case, you mentioned the only difference is the thickness of the base metals welded. The question you should ask yourself is whether the production quantities are "high" and limited to a narrow range of thicknesses, stay with two separate WPSs and give the welders only a copy of the WPS that includes the thicknesses being welded. If the welders are welding parts that include a wide range of thicknesses and the quantities are relatively low, give the welders copies of both WPSs. If the production requirements are such that the part they are welding includes base metal thicknesses included by both WPSs, combine the two WPSs into one WPS and provide the welders with the one combined WPS.





Best regards - Al