Thin material welded to thick material (shims)

By sclqa Date 10-21-2013 03:44

I have a client who is being a pain in the butt. We have to tack weld shims to very thick steel assemblies. The thinner material (shims) thickness is below the the thickness range over lap between D1.1 and D1.3 and client won't let me use either standard alone. The client ( no clue about welding) wants the typical documents (PQRs, WPS etc.) I tried to do a combo "workmanship" tack weld and then do a pull test procedure using BOTH standards but the client is expecting tensile pull tests from a lab for the PQR - because somewhere he read that PQR docs with tensile tests should be done. The tacks are for small locking tabs of shims between to thick parts.
I have suggested a peel/pull test to verify that the tacks are difficult to break. One of the existing larger materials is unknown (no drawings) but it is either a medium carbon or low alloy steel and can't be removed for material testing. The part is so large that I doubt the part will even know it was tack welded. Certainly the tack should affect any heat treatment in the part. I have talked to several labs but none will touch it due to all the unknowns.
Any P1 electrode should work and the weld puddle should start on the thicker steel and feed quickly in and out of the shim so as not to melt it, but how do I verify the weld with a test between the two standards?
Thanks
sclqa

By 803056

Date 10-21-2013 14:16

Your customer has the responsibility of specifying the requirements of the project. When the project involves more than one standard, the customer should specify when each of the standards apply.

Your customer should also define the materials of construction so you can qualify a WPS to the standard he specifies.

This sounds like a hot potato and the labs are wise to steer clear until all the necessary information is provided.

Have you considered retaining the services of a welding engineer to provide direction to both you and your customer?

Best regards - Al

By G.S.Crisi (****)

Date 10-21-2013 19:58

First of all, let's check if the word "shim" means the same thing for you and me.
Back in my days of erector engineer, "shim" was a strip of variable width (1 to 2 inches), variable thickness (one thousandth of an inch for rotating equipment to maybe half an inch for refinery towers) and variable materials (brass or stainless steel for rotating equipment to plain carbon steel for structural steel) that were put between the equipment concrete foundation and the equipment base to adjust their position (vertical or horizontal), level and plumbness. In the case of rotating equipment they were used also to achieve the required alignment between the driver and driven machine.

If this is so, well, I've never welded the shims to the thicker equipment base, nor never heard that the shims had to be welded. Even more, I worked under the stringent supervision of companies like Sargent and Lundy Consulting Engineers, from Chicago, and The Lummus Company, from New York.
Take into account that after the equipment is plumb and levelled the base is grouted to the concrete foundation, which prevents the shims from moving from their position.

Giovanni S. Crisi
São Paulo - Brazil