Has anyone out there heard of equip 1

[mcguire]

Has anyone out there heard of equipment to orbitally laser weld stainless 316 tubing. TIG welds require high sulfur levels in the steel which screws up corrosion resistance.
Tube diameters 1/2 to 1 inch. Wall thickness 0.030 inch.

 

[GRoberts]

McGuire,
I'm not so sure that tig welding requires high sulfer levels, I think that they just require similar sulfer levels. The sulfer affects the currents in the weld pool, and if one side has more sulfer than the other, the weld penetration will favor the side with more sulfer, and may miss the joint.

 

[mcguire]

Good point. I ask the question because ASME BPE 316 tubing calls for 0.005% minimum sulfur in order to make weld penetration better when TIG welding. If the weld could be done with a laser, the sulfur would be unnecessary and could be kept to 0.001% or less thereby improving cleanliness for use in processing media for biotech, pharmaceuticals, and microprocessors.

 

[GRoberts]

While the spec calls for .003 min sulpher to improve GTA welding penetration, which it does, I don't think that you would need it because of the thin wall. I haven't seen any info on it, but if you do go with laser welding, I wonder if you have to get matching sulpher base metals so as not to affect the liquid metal currents? I wouldn't think it would be as much of a problem though, as penetration does not depend on liquid convection. Another thing you might consider is looking for a plasma welding system. They can do keyhole welding just like a laser. Should be a lot cheaper too.

 

[APMINC]

Have you tried electron-beam welding?