High purity pipe "rewelding questions"

By Dano Date 04-09-2002 21:24

We are looking for some input.
Is it possible to reweld and reuse the following
High purity gas lines.

NF3
Cl2

All material is ss316 tubing, EP10ra, orbital welded.

All lines have been nitrogen purged, and disconnected prior to
Rewelding.

Will the line re-qualify under standard Semi conductor specifications?
For these gases.

Thanks
D. Hoodenpyle
Kinetics Corp.
Project Coordinator

By Niekie3 (***)

Date 04-10-2002 17:22

I am not familiar with the NF3 gas, but I reccon the same reasoning will hold for it as for the Chlorine gas line so here is my explanation:

If you have high purity gases, then I assume there is no electrolyte present in the lines. With no electrolyte, you should have no corrosion. With no corrosion, you should have no degradation of the material caused by these gasses. (Contrary to popular belief, chemicals (except for H) do not "penetrate" the material. This only happens when corrosion occurrs or to plastics and porous materials.)

You should therefore have no problems re-welding them. I can not comment on the semi-conductor question because I am not in that industry.

Regards
Niekie Jooste