sugaring on stainless

[Nathan128]

Ok tig welding a 10" 304h stainless joint. Using 308h wire as per procedure. Pure argon back purge and 50 degree preheat. Every time we go to even tack we get sugar. We've tried different purge flow rates. Different bottles. Redoing the dams. Re cleaning it. And nothing. This joint is one end of a pup piece 8" long and the other end has a big flux core shop weld. Starting to wonder if that could have been heated too much and causing it. We've also tried wiping down with vinigar to neutralize any acid wash. I dunno grasping at straws. Ideas?

[ja baudin]

Ok tig welding a 10" 304h stainless joint. Using 308h wire as per procedure. Pure argon back purge and 50 degree preheat. Every time we go to even tack we get sugar. We've tried different purge flow rates. Different bottles. Redoing the dams. Re cleaning it. And nothing. This joint is one end of a pup piece 8" long and the other end has a big flux core shop weld. Starting to wonder if that could have been heated too much and causing it. We've also tried wiping down with vinigar to neutralize any acid wash. I dunno grasping at straws. Ideas?

Vinegar is acidic, water will do a better job than vinegar for sure to remove an acid wash.

[Nathan128]

sugaring on stainless

Ya the vinigar was an idea someone had heard of and we thought what's the worst that could happen

[CODE4]

What kind of joint? Material thickness, heat settings? Attach a picture of the weldment

[Nathan128]

sugaring on stainless

Butt joint. And the pipe is vertical so it's a horizontal weld. 1/2 wall thickness. And I can't do a picture cuz there's no cameras allowed where it is

[Nathan128]

sugaring on stainless

Oh ya and heat settings around 70-90 ish. Running off a Lincoln 300 diesel. Everything is tarped right in so there's no draft anywhere. The back purge also puts a lighter out making us think the purge should be pretty good. I'm at a loss guys. Thanks.

[cruizer]

Oh ya and heat settings around 70-90 ish. Running off a Lincoln 300 diesel. Everything is tarped right in so there's no draft anywhere. The back purge also puts a lighter out making us think the purge should be pretty good. I'm at a loss guys. Thanks.

Talking Vantage/ 300D, 300SAE? Correct polarity

[Ltbadd]

Oh ya and heat settings around 70-90 ish. Running off a Lincoln 300 diesel. Everything is tarped right in so there's no draft anywhere. The back purge also puts a lighter out making us think the purge should be pretty good. I'm at a loss guys. Thanks.

Wow, I've never used this much flow, if the flow is too great it could be drawing in air. Is this an open root weld?

[Nathan128]

sugaring on stainless

Sae 300 and the purge flow was around 7-10cfm. Tried all sorts of flow rates actually. And ya open root. We're trying to get an oxygen meter. Correct polarity for sure.

[Ltbadd]

Using Heat Tape or diffuser

Sae 300 and the purge flow was around 7-10cfm. Tried all sorts of flow rates actually. And ya open root. We're trying to get an oxygen meter. Correct polarity for sure.

You could try using heat tape to cover 3 of the four quarters of the open root, of course welding the exposed open quarter. Then pealing back the next quarter and proceeding until the root is finished.

Also are you using any kind of diffuser to introduce the argon purge? If not the unabated flow could be causing turbulence inside the pipe, in fact I've always used some sort of diffuser, even a length of 1/4" OD copper tube with a number of small holes drilled around the circumference works good, just be sure to pinch one end of the tube closed, while attaching your argon line to the open end. I've also used a pneumatic muffler which works very well

[Nathan128]

sugaring on stainless

We've been using that aluminum tape they use on duct work to tape it. Don't have a diffuser for the purge, just a open hose. Yesterday we taped the whole joint and let it purge for an hour and a half at 10cfm then came back opened an inch or two turned down the purge a bit to say 7cfm and same thing sugar on the tacks. Not horrible sugar but it's still there. I'm starting to think wire could be no good? Or the 308h (h stands for high carbon) is it just supposed to look a bit sugary? It's gonna be x rayed so I don't wanna take the chance unless the higher ups say it's ok.

[Ltbadd]

We've been using that aluminum tape they use on duct work to tape it. Don't have a diffuser for the purge, just a open hose. Yesterday we taped the whole joint and let it purge for an hour and a half at 10cfm then came back opened an inch or two turned down the purge a bit to say 7cfm and same thing sugar on the tacks. Not horrible sugar but it's still there. I'm starting to think wire could be no good? Or the 308h (h stands for high carbon) is it just supposed to look a bit sugary? It's gonna be x rayed so I don't wanna take the chance unless the higher ups say it's ok.

if you haven't already, I'd check all the connections from the purge bottle, pinch off the end of the purge line, and with pressure in the line you can put the hose in a bucket of water to check for leaks.

I still recommend a diffuser on the purge line.

[CODE4]

Are you using high carbon filler as per a specification? Why not 308L or 316L?

[Nathan128]

sugaring on stainless

Ya we checked all lines and connections. And ya the material is 304h so the procedure calls for 308h wire. I was asking about that already. I'm about ready to put in a carbon root and see if they call me on it lol.

[Nathan128]

sugaring on stainless

We'll guys we did two joints that went well. We ended up having the argon purge at 40cfh for our main purge and a second going through the joint at 10 cfh. The only thing we could think of was since it was 60' tall and outside we needed higher purge to push out the cold heavy air. Te purge flow rates seem rediculously high to me but that's the only thing that was working.