Corrosion treating between welded parts?

admin

I figure you guys that work in the industry would know about this.  Is there anything that can be done to add corrosion resistance in between pieces that have been welded together, such as welding a plate to a beam ?    I fear the obvious answer is to lay a bead all the way around to completely seal it up.    One option I could try prior to painting is to apply a liberal amount of 3M  Mar-hyde type rust converter and see if it will run down in between the pieces.
Reply:If the pieces are dry then stitch them together and afterward run a bead of caulking the same size as the weld stitches.  Choose a caulking rated for outdoor use that will take paint.  You don't need to use any rust converter.  If you keep the air and moisture out of the joint there will be no corrosion.  In one situation I worked in the architect asked for seal welds on everything before galvanizing.  The result was buckling and distortion problems.  The solution was to stitch weld the assemblies then after galvanizing to run a bead of silver caulking that matched the colour of the zinc. If we had not caulked the moisture would have reached between the mating surfaces.  Rust would have happened and it would have bled out on to the surface of the zinc.
Reply:I know a big corrosion resistant paint used in the autobody industry is weldable primer. Its a zinc based paint that keeps the metal from rusting once welded.
Reply:Originally Posted by lotechmanIf the pieces are dry then stitch them together and afterward run a bead of caulking the same size as the weld stitches.  Choose a caulking rated for outdoor use that will take paint.  You don't need to use any rust converter.  If you keep the air and moisture out of the joint there will be no corrosion.