Welding for heat treat area.

[Steelforbrains]

We are in the process of repairing shelves that are used in a heat treatment area. The shelves are constructed of 1 1/2" square tubing and 3/4" to 1" round tubing. I would say that they range from 16 ga to 11 ga and they are all 304 SS. The shelves are used to hold aluminum rims and are run through an oven on a conveyor. The problem is that the welds are cracking. I am planning on TIG welding the cracked areas. Do I need to consider using any special filler wire for this application?

 

[metengr]

First, after you visually locate the cracks, you might want to have some nondestructive testing (NDT) performed adjacent to the visual cracks to make sure that you don't miss any in the stainless steel tubing parent metal. The nondestructive test method to use is Liquid Penetrant testing (PT). If you don't have this capability, bring a qualified NDT contractor in to do this work. It is not that expensive and will assure proper repairs.

After locating all of the cracks, locally grind them to removal in the square and round tube members. Do NOT weld over the cracks, you need to remove them to restore structural integrity. Verify crack removal using Liquid Penetrant testing. If the cracks happen to have propagated to a depth of 95% of the wall thickness of the tubing, stop grinding and use the remnant material for backing during weld restoration.

Clean all repair areas prior to welding, and use the GTAW process with ER308 filler metal. Preheat is not required.

 

[unclesyd]

Real quick what is the exact location of the cracks?
What was the original welding process?

If it through the center of the welds you have a strength problem, normally not enough weld metal in the proper place. In your case it is probably due to thermal expansion and weight of the parts.
The cracks have got to go before you reweld the racks.

 

[DAVIDSTECKER]

Look into 310 SS. Better for heat