Need a few tig tips

[Jorville]

I am still trying to get an acceptable weld on 3/16 mild steel. I can make the top side look really good. the bottom is not an acceptable 100%. there is a little suck back. This is an open root weld. Roughly 37 degree bevel. I have gaped it 1/8 and 3/32 used 3/32 filler and 1/8 filler. The 3/32 filler seems to work the best, wit a 1/8 gap but still not an acceptable 100% weld. I have yet to see a key hole some may call a fish eye. anyone have an idea as to what I am doing wrong.

 

[Shield Arc]

Do you use the lay wire technique, or dip the filler rod?
I like 37 1/2 degree bevels. 3/32-inch gap, and use 1/8-inch filler rod. I run around 90 to 95 amps. For the hot pass I only go up 10-amps, and switch to 3/32-inch filler this helps prevent suck back.

 

[Jorville]

Shield Arc
I dip the rod, I tried the lay wire and did not have a lot of luck with that. The bevel is hand ground so it is close to 37 degrees, not perfect. I tried to match what the butt weld pipe fittings look like, land and all. I am using that old Miller Dial arc so the amperage is a guess. I though I should be able to see a key hole.The range selector is set 40 to 190 and the dial is at 80%, I am not sure where my foot is at, just try and keep a puddle.

 

[Shield Arc]

I don't use a land at all for Tig welding open root. I do for SMAW. When dipping the filler rod wait until you see the key hole before dipping the filler rod.

 

[Shield Arc]

Couple thoughts:
How are you sharpening your tungsten? For open root welding I like a real long taper.
Are you walking the cup? If so I bevel the cup a little bit.

 

[Jorville]

shield arc
The tungsten is sharpened fairly long maybe not as long as the one you show. I will try a little longer. The distance between the two pipes is pretty narrow so I was trying to just go straight with no side to side movement. The pipe is eight joints of 2 1/2 inches and four will be 1 1/2 inches. The 1 1/2 pipe has a wall thickness of .130, a tad over 1/8 inch. I haven't tried the thin weld yet. I have yet to see a key hole, that is why I went to a 1/8 gap. And I still do not see a key hole. I am doing something wrong somewhere.

 

[Shield Arc]

I still do not see a key hole. I am doing something wrong somewhere.

Just set there with the power on, the key hole will appear. A lot of it has to do with torch angle. You'll have to play with that to see what angle works best for you.

 

[Mark @ Everlast]

I would not put a big key hole in it. You really don't see the key hole until it just appears. It's not as big as you think. It just starts to open up and bam! you add wire.

 

[Jorville]

Just set there with the power on, the key hole will appear. A lot of it has to do with torch angle. You'll have to play with that to see what angle works best for you.

I went down to 3/16 material and turned the machine down to 65% of the 40 to 190 range The first coupon is 3/32 gap, and 3/32 filler rod. I never really saw a key hole, just fuzzed the two pieces together moving the torch back and forth a little, and added a little filler. Second picture is the under side it has a lot of suck back and is very wide. Why is the under side so wide. The third picture the pieces are at a 1/8 inch gap There I saw a small keyhole and added more filler the key hole disappeared though and I continued to add filler. The underside is still wide and still has a little suck. Why are the undersides so wide. I though I would get a 1/8 or so bead on the underside. You can see I stopped midway just to see what the underside looked like.

 

[Shield Arc]

Why are the undersides so wide.

Because you are cooking the plate. Too much heat, or too slow of travel speed.
Try a 37-degree bevel. 3/32-inch gap, and use 1/8-inch filler rod. Along with the lay wire technique. Push real hard on the filler rod. Like you are trying to push it through the plate. Also make sure the puddle is just a hair bigger than the width of the 1/8-inch filler rod.
I think you will a lot better results just starting out with open root welding.

 

[Shield Arc]

Here is a picture of open root welding with 6010. But it is a good picture of a key hole.

 

[Jorville]

Shield Arc,
I was thinking along the lines of too much heat. I will cut some more coupons today and give what you suggested a try. I was going to try a bevel with no land also. And turn down the heat. Thanks

 

[Jorville]

Here is a picture of open root welding with 6010. But it is a good picture of a key hole.

Shield Arc, I have turned the machine so it just makes a puddle and still get a wide weld on the under side. On another post I have about this job someone suggest using 6010 root and 7018 rest of the way out. I don't have any 6010 on hand so I used 3/32 6011 on a coupon. by using a little more amperage than I was using with the tig I got an acceptable weld on the back side. The only problem is the flux on the back side. I can't get it off inside the pipe and as it breaks off over time it will destroy the pumps. I have a 110 wire machine I am tempted to use and see what I get. Can a guy get any different results with an inverter tig machine or would the end result be the same?

 

[Shield Arc]

I always wondered how people in the pipe trade deal with slag in the pipe. I worked around pipe welders all my life, but never ask them!
I live in a county with three Navy ship yards. The welders in these yards tell me all pipe welding is done with Tig.
I just love inverter welders, way more control over the puddle.

 

[Jorville]

I always wondered how people in the pipe trade deal with slag in the pipe. I worked around pipe welders all my life, but never ask them!
I live in a county with three Navy ship yards. The welders in these yards tell me all pipe welding is done with Tig.
I just love inverter welders, way more control over the puddle.

Do you know anyone who would be interested in a small pipe job?

 

[Gary Fowler]

I always wondered how people in the pipe trade deal with slag in the pipe. I worked around pipe welders all my life, but never ask them!
I live in a county with three Navy ship yards. The welders in these yards tell me all pipe welding is done with Tig.
I just love inverter welders, way more control over the puddle.

Slag can be removed but with difficulty using citric acid or other mildly acidic acid to dissolve scale and slag. For many years now all piping that requires "pickling" before use on pumps, steam lines to turbines, oil service to turbines, etc will be done with TIG process and then hot oil flushing until there is no residue on the filter screens. All oil lines I have see for the last 30 year have been made of stainless. Sometimes the cleaning process might take a week or more to do. In fact in most instances, TIG root and hot pass is more efficient (manhour and xray quality wise) than doing SMAW welds which is why most piping welds are now done with TIG.
Most high pressure steam lines to turbine drives will be blown clean with high pressure/high temperature steam. This heating and cooling cycle loosens scale and other debris sufficiently to allow no damage to turbine blades. A polished target (usually 1" SS bar) is inserted in the center of the pipe on the downstream side of the steam blow and must be free of pings for two consecutive blows for the pipe to be considered clean.

 

[Gary Fowler]

For TIG prep, I grind the bevel to 37 Degrees with feather edge landing. Depending on the size pipe or length of plate in your case, a gap of 1/8 to as much as 3/16" or more is set. The gap will close a bit during welding and if the weld is large enough like for instance a 24" or larger pipe, you may start with with 1/4" at the bottom and use a 1/8 or 5/32 rod then switch to 1/8 as the gap tightens and perhaps finish with a 3/32. I have had to take a grinder and widen the gap when it closed completely up.
In your case, I think you are running too many amps, not feeding enough wire and possibly travelling too fast. You need to keep the key hole open in order for the bead to be above flush on the inside. If it closes up due to travelling too fast, stop and grind the weld thin so you can burn thru it and then continue with keyhole welding.

 

[Shield Arc]

Slag can be removed but with difficulty using citric acid or other mildly acidic acid to dissolve scale and slag. For many years now all piping that requires "pickling" before use on pumps, steam lines to turbines, oil service to turbines, etc will be done with TIG process and then hot oil flushing until there is no residue on the filter screens. All oil lines I have see for the last 30 year have been made of stainless. Sometimes the cleaning process might take a week or more to do. In fact in most instances, TIG root and hot pass is more efficient (manhour and xray quality wise) than doing SMAW welds which is why most piping welds are now done with TIG.
Most high pressure steam lines to turbine drives will be blown clean with high pressure/high temperature steam. This heating and cooling cycle loosens scale and other debris sufficiently to allow no damage to turbine blades. A polished target (usually 1" SS bar) is inserted in the center of the pipe on the downstream side of the steam blow and must be free of pings for two consecutive blows for the pipe to be considered clean.

Gary I was hoping you would see this post. Nice to have a pipe welder as a member to keep us structural hands in line when it comes to welding pipe.
Thank you so much for the education!:thumbsup: Don't know why I never ask pipe fitters on the job.

 

[Jorville]

For TIG prep, I grind the bevel to 37 Degrees with feather edge landing. Depending on the size pipe or length of plate in your case, a gap of 1/8 to as much as 3/16" or more is set. The gap will close a bit during welding and if the weld is large enough like for instance a 24" or larger pipe, you may start with with 1/4" at the bottom and use a 1/8 or 5/32 rod then switch to 1/8 as the gap tightens and perhaps finish with a 3/32. I have had to take a grinder and widen the gap when it closed completely up.
In your case, I think you are running too many amps, not feeding enough wire and possibly travelling too fast. You need to keep the key hole open in order for the bead to be above flush on the inside. If it closes up due to travelling too fast, stop and grind the weld thin so you can burn thru it and then continue with keyhole welding.

Gary, Thanks for the input on this job. It is a little more complex than I originally thought. I have everything cut and drilled for this piping job but the tig welding part is not yet acceptable. I have been looking around locally for someone to weld this but have had little luck so far. I wanted to get this installed by this fall but that is not going to happen.

With a tig weld it looks to be not a lot of clean up, or for sure a lot less than a smaw. There will be a dirt magnet installed on this system, but will it get all the dirt, who knows. On another forum a fellow posted a picture of a Taco pump that failed and inside the pump was some very fine particles of something.

 

[Jorville]

Gary, I ran a couple of coupons on 3/16" hot rolled material with the 1/8" gap and ground to a point , no land, it looked pretty darn good. A few more of those coupons and I should be up to speed. I ran roughly the same amps as I did before with the land, But with the land and a 1/8" gap I could not get the key hole. So the problem was having the land.

I do not have the cape ability to do hot oil flushing or a high pressure/high temperature steam blow so I would assume filling the piping with citric acid before it is installed and let it sit for awhile would be sufficient. Then flush with water, Yes, no??? If so how long should the citric acid sit in the pipes? The pipes are two, 2 1/2" pipes about 3 feet long and Two, 2 1/2" pipes a little over a foot long, and one two inch pipe about 16" with caps on each end.