purge dams for tig welding
purge dams for tig welding
(OP)
looking for a material that will dissolve in hydraulic oil, that we can make a purge dam from - closure weld on a A312 316L hydraulic piping system, that we want to pressure test with oil .





RE: purge dams for tig welding
Is it impractical to purge the whole system?
RE: purge dams for tig welding
How big a system is it?
What size is the pipe?
One thing you might want to look into is use N2 as the back purge. We do this all time with very large SS systems.
RE: purge dams for tig welding
Just type "rice paper purge dams" into google.
There are dozens of soluble paper dams available.
They all speak of dissolving in contact with water but you should be able to find out from manufacturer if they will dissolve in contact with oil,
Regards,
Kiwi
RE: purge dams for tig welding
http://www.robvon.com/
Another possibility is use flux coated TIG wire. These wire very little if any residue using a feathered edge weld prep.
http://www.qwpinc.net/NEW/SS_flux_tigwire.pdf
RE: purge dams for tig welding
The water used to hydrotest the system is usually flushed to remove any soluble contaminates and suspendable solids once the initial hydrotest is completed. One of the contaminates is the material from which the soluble purge dams are made.
Do you anticipate replacing the contaminated oil with fresh oil once the system is hydrotested? If not, an inflatable bladder type purge dam may be a better alternative to the water soluble dams.
Best regards - Al
RE: purge dams for tig welding