Carbon Arc Gouging on 316L stainless

[StoneCold]

I want to cut a fitting off of a 16" O.D. flange by removing the welds. This is a perfect application for carbon arc gouging but the catch is the flange and fitting are 316L stainless. Will it ruin the stainless because of the heat or can the cutting conditions be changed enough to make it work out? This is a situation where the corrosion resistance of the stainless is important. My other options are grinding, plasma arc cutting, or maybe waterjeting if I can talk the waterjet owner into it.

What do you think?

Thanks
Stonecold

 

[metengr]

Use plasma arc cutting - clean, precise and efficient.

 

[EdStainless]

I'll second plasma. You could use carbon arc, if you want to go back and grind enough metal off to remove the damaged metal.

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[StoneCold]

The problem with plasma cutting it is that it is hard to get close enough to the sides of the welds. So if I use a plasma torch I will have to do a lot of grinding. I was just curious if anyone uses the gouging method on 316ss. I have used it a bunch of times in the past on carbon steel and it works awesome for cutting out old welds.

Thanks
Stonecold

 

[GRoberts]

I can tell you that carbon-arc gouging is used extensively in the foundry industry for stainless steel. With good technique and proper post-gouging cleaning, it does not normally present a problem when the base metal is sound.

 

[metengr]

You can air carbon arc gouge with the necessary precautions and proper technique - watch your heat input in the surrounding material, prepare to grind back material that has carbon contamination, and watch your air flow. I saw it used on some heavy wall austenitic stainless steel steam chests.

 

[deanc]

Have used it many times in the past,fast,works good,and you will need to grind.

Keep your carbon stick out short...and make sure the air holes are on the bottom

 

[unclesyd]

Our process is by nature one of the most corrosive in terms
of IGC SS around. In our fab shop we allow both carbon arc gouging and washing with a TIG torch. With a very minimum of grinding we see no detrimental performance in the weld proper or the HAZ in service.
We allow arc gouging on process vessels where we discover less than satisfactory weld metal performance. There is usually no other preparation. We also repair thermal fatigue cracks on SS vessels by the same method.

Early on, 1960 I ran numerous lab and field tests comparing there methods for cutting SS, iron powder torch, carbon arc gouging, washing with a TIG torch.
The initial test were run using both 316L and 304L with carbon at 0.035 max. With no other prep there was some difference in weld performance in the Huey Test. Some of the difference was confirmed to be for the variability in the electrode as deposited chemistry. Repeating the test with the base metal carbon limited to 0.030 max and using an electrode with a deposit analysis of .035 max carbon results were vastly improved. Changing the base metal to 0.020 max carbon with an electrode with 0.025 max carbon
there was no discernible difference in the corrosion behaviour. Striker tests of sectioned coupons no increase in precipitation at the grain boundaries. The last test coupons were installed in process. These coupons

 

[unclesyd]

I had a finger slip.
were made for SS with a max carbon of 0.015 with the both S and P controlled. They showed no effect of either arc gouging or washing by TIG torch.
We still allow back gouging in the fabrication of SS storage tanks even though the plate is cut with plasma. All tanks are welded with SMAW with full penetration and 100% RT.
We do reserve the right to monitor the performance of the person doing the arc gouging. We have a qualification procedure for our people. It has been experience that 90% of the people who try arc gouging are given the torch and told to go at it.

I afreed that plasma is the way to go but ther are time it's hard to get away from arc gouging.

 

[palecactus]

with the heat turned way down with a plasma cutter you can scarf the weld out with out the drastic results of the carbon arc.