High Temperature Purge Dam
High Temperature Purge Dam
(OP)
Is anyone aware of any soluble purge products that will withstand elevated temperatures, i.e 600°F minimum?
We have a closure weld at a nozzle that must be back-purged, and the nozzle is not of sufficient length such that we can get a paper purge in without burning up the dam. Being a closure weld, there is no access to remove any sort of inflatable bladder.
We have a closure weld at a nozzle that must be back-purged, and the nozzle is not of sufficient length such that we can get a paper purge in without burning up the dam. Being a closure weld, there is no access to remove any sort of inflatable bladder.





RE: High Temperature Purge Dam
Past that, thin sheets of stainless steel or even aluminum foil. You may need an origami expert to help you get a reasonably shaped shield/dam through the nozzle outlet and back out again...
Or am I misreading what you are doing?
RE: High Temperature Purge Dam
Why can't you use a small steel tube with backing gas applied to the weld root region through a window 180 degrees of where the welder is pulling the root? Seen it done many times in the field. Granted you will have a small region where backing gas will not be applied when you close the window. However, this is a small region and should not pose a problem.
RE: High Temperature Purge Dam
RE: High Temperature Purge Dam
Met: That may in fact be our only option. Unfortunately, our material is P91.
RE: High Temperature Purge Dam
Just remember that the majority of purge problems is too much flow on the gas side. It doesn't take much gas to purge a weld.
If your specifications will allow different approaches the links below will show a cross section of what's available and if nothing wlse keep them in mind for future purge problems.
You haven't mentioned the size or material, but maybe able to use a non-noble gas in the system.
What's available
http://w
Backing rings and consumable inserts
http://ww
http://www.robvon.com/
Ceramic backing rings
http://www.cerbaco.com/index.html
variations on a theme
http://www.aquasolwelding.com/
RE: High Temperature Purge Dam
RE: High Temperature Purge Dam
Mike Halloran
Pembroke Pines, FL, USA
RE: High Temperature Purge Dam
Try a teflon dam made in 4 pie-slices and secured with metal foil tape, as far from the weld as possible. May need 2 dams, one on each side of weld. Tie the segments together with wire, and attach a pull-wire to collapse the dam(s) and extract them. Take care not to melt the pull-wire.