[HeavyOil]

Howdy from the coastal bend of Texas.
I have a little problem that i run into frequently in my line of work and I would like to hear some suggestions on how I might lessen the amount additional work associated with removing one welded plate from another.

Let me first explain the scenario. If I have a large flat surface made of steel, such as the deck of a barge, and to this surface I have welded many other steel plates of 1" to 2" thickness in T-joints with double fillets sized to the strength of the plate, what would be in your opinion the fastest way to clean off these plates to within 1/16" of flush, leaving a fairly uniform surface.

Let's hear it!

[noddybrian]

Hi - if I'm understanding the job as being able to remove the parts while not damaging the deck or leaving a large amount to grind to leave the area trip hazard free if you have access to " air arc " gouging I would use that to remove the welds completely as it can be done with quite accurate results - if you don't have sufficient power to run one ( think 350 amps upward - ideally more like 500 ) then a specific gouging nozzle using oxy / fuel is probably next best - if the plates are individual then you should be able to drag them sideways to break them free even if slight amounts of weld remain - a picture always helps visualize the problem if you can post one.

[Otto Nobedder]

Here's a search page for ArcAir products.
https://search.yahoo.com/yhs/search?p=a ... mp=yhs-004

Brian is right, this is the fastest, most efficient way to remove welds.

It does take a bit of practice, but if you're an accomplished MMA welder, you'll find this is just stick-welding in reverse, as far as technique.

With practice, you can minimize post-cut grinding.

Steve S

[plain ol Bill]

Arc air definitely my choice for work like you describe. Lots of power - even if you have to parallel up two or three machines, large carbons, lots of air, a respirator, and ear plugs. You can remove large amounts of metal with one of these or do very delicate work also. Like Otto says - with a little practice there will be very little grinding to clean up for re-welding.

[HeavyOil]

OK, I know that carbon arc gouging is the standard method for removing welds. The problem is that I am at the end of a two month scope at one of the US' largest fabrication yards, which consists primarily of removing welded steel structure from the deck of a vessel. The amount of additional time spent repairing gouges into the vessel deck and the grinding, and then more grinding, has completely raped our schedule and we are still not complete. Not to mention the damage to the coating on the inside of the ballast tanks from washing the weld scars off with torches and the gouging itself.

I'm looking for innovative ways to remove the welds and metal in one go. Eliminate the massive amounts of repair and rework, and the grinding, grinding, grinding. Cut everything within 1/8" of the deck (a sixteenth is better but 1/8" is technically the spec) on the first pass and leave a paint ready surface.

This is not the first time we've done this. I'm just pissed and frustrated right now and trying to find ways to make this easier in the future. Because the vessels always come back when the job is over.

I have some pretty good concepts in mind right now but no way to test them. I'm just trying to gather ideas for the future.

Thanks

[MinnesotaDave]

Have you tried high amp plasma cutting/gouging?

If it were me, I'd want a track design running a plasma cutter (or torch) so I could turn it on and run my travel speed with a crank handle.

Specially designed track system to run flat against the deck and the cutting would be more accurate with fewer gouges (or none) into the deck.

(Maybe one is already made?)

[HeavyOil]

I appreciate that suggestion. The yard tested a not yet released plasma gouging system from Hypertherm for this scope but I believe it was manual and their complaint (in addition to the cost) was that the person gouging could not see where one plate ended and the deck plate began. I've gouged at home with my plasma cutter and I remember being able to distinguish between plates well but I still under cut the welds too.

Anyway one idea I've had is to use a track torch with a riser tip http://m.grainger.com/mobile/product/MI ... ting-6PHH9
Erich might work well on thinner material but would not be able to cut most of the stuff we have been removing.

Any way to keep y'all interested, here is was the project we completed. https://youtu.be/Tt1fkfnNHX8
I'm cleaning off the barge in that video.

[Boomer63]

I appreciate that suggestion. The yard tested a not yet released plasma gouging system from Hypertherm for this scope but I believe it was manual and their complaint (in addition to the cost) was that the person gouging could not see where one plate ended and the deck plate began. I've gouged at home with my plasma cutter and I remember being able to distinguish between plates well but I still under cut the welds too.

Anyway one idea I've had is to use a track torch with a riser tip http://m.grainger.com/mobile/product/MI ... ting-6PHH9
Erich might work well on thinner material but would not be able to cut most of the stuff we have been removing.

Any way to keep y'all interested, here is was the project we completed. https://youtu.be/Tt1fkfnNHX8
I'm cleaning off the barge in that video.

It sounds like you got to the heart of the delays you are having with this project; the person doing the burning (no matter what process) couldn't see the deck from the welded lugs. Taking a bit more time on the burning would give you ... but you probably already know this!
Gary

[plain ol Bill]

If you are having that much rework take that gouge away from the guy and beat his butt with it. That is NOT acceptable and you need to find someone that know's what they are doing.

[Otto Nobedder]

HeavyOil,

My mind is drifting toward a magnetic-based (like a heavy mag-drill) machining tool that will, like a track-torch, pull a 75* v-cut carbide-toothed cutter wheel slowly along the weld. 75* so the point can dig to the root of the weld without undercutting the throat.

I used similar annular cutters to cut out aluminum welds in a hand-held die-grinder, and it worked great, but hand-held is out for steel. Some sort of base to rigidly hold the cutting tool would be a must. Perhaps even pneumatically driven, so water-based cutting/coolant fluid can be used without risk of shock?

Just thinking out loud.

Steve S

[HeavyOil]

Well Bill, it's not a single somebody. It's about 30-40 somebodys and about 40,000 mhrs and there is definitely a big difference in the amount of repair required based upon the welder doing the work but I can't control who the yard is putting on what project.

Steve, I've thought about some sort of machining, like horizontal milling sounds great but i had assumed the time and cost would be too great. I don't really know the first thing about machining, except that there are companies that do field machining and they charge A LOT.

If you could send a link to those blades you were just talking about I would like to see that. Any machine can be made it takes enough need to make it profitable.

Thanks,
Garry

[weldin mike 27]

Bug o systems and Gullco systems make magnetic track attachments for cutters and gouges. They are high end machines.

Mick

[Boomer63]

If you are having that much rework take that gouge away from the guy and beat his butt with it. That is NOT acceptable and you need to find someone that know's what they are doing.

I would not have put it that way ... but that is what I would have meant!
Gary

[noddybrian]

Have to say the few times I break out the air-arc is because I want minimum collateral damage - would'nt call it surgical but it's the best option I have & I get pretty good results - if the operators are that bad using it I have to question would they be any better with different equipment? if said is equipment is very expensive or needs skill to setup & use I don't think the results will be any better - seems like they need specific training for gouging if they are just general welders & have not used it enough to be proficient - but based on the number of hours I should have thought they would pick it up fairly fast - I do think an oxy fuel cranked torch on a track cutter would work quite well except that it would normally require acetylene - not seen one for propane which would escalate the costs - bottom line seems to be getting good staff - dare I ask if this is a union job ?

[Otto Nobedder]

Steve, I've thought about some sort of machining, like horizontal milling sounds great but i had assumed the time and cost would be too great. I don't really know the first thing about machining, except that there are companies that do field machining and they charge A LOT.

If you could send a link to those blades you were just talking about I would like to see that. Any machine can be made it takes enough need to make it profitable.

Thanks,
Garry

Here's a very approximate example, and I'll keep digging for what I actually meant.
http://www.bing.com/images/search?q=car ... ajaxhist=0

Steve S

[Otto Nobedder]

Garry, this would cut a lap-weld beautifully, if it can be held and directed on the intended path.

http://www.bing.com/images/search?q=car ... ajaxhist=0

Steve S

[plain ol Bill]

Garry I understand your quandary. Been on many of the jobs that require 6" heavy wall pipe for hand rails. Economics considered a gouge is still your most economical and efficient method IMO. Will machining accomplish the task - sure, just be prepared for the expense.

[ldbtx]

I'm visualizing a device -- don't know if it's commercially available or not, but a competent machine shop could build it -- that's basically 2 mag drill bases connected by a couple guide bars, and a hand cranked or power feed screw. A carriage on the bars/screw carries a drive motor and a slitting saw as Steve posted. With the right arbor, this gadget could get within a 1/4" or less of the deck and slice the upright plate off "slicker than scum off a Louisiana swamp" (to quote CW McCall).

[Otto Nobedder]

The sign said, "clearance to the twelve-foot line", but them chickens was stacked to 13-9.
We shot that tunnel at a hundred and ten, like gas through a funnel or eggs through a hen...
Took that top row of chickens off, slicker than the scum off a Louisiana swamp...

Wolf Creek Pass.

Steve S

[BLURAT]

Have you looked at the JetEdge mobile water jet cutting system. I found them online. It sounds right up your alley. The machine has to be cheaper than paying day wages on 30-40 people, plus all of the related cleanup and damage control.
We have had carbon arc done at my place of employment on 2 of our tractor tugboats in the last 4 years (while in a major west coast drydock). The men I saw doing the work were extremely skilled and the collateral damage was extreme (burned paint and the slag everywhere) and they did an admirable job of trying to protect the non affected work zone.

The websight specifically mentions that the system is optimal for large flat decks, tanks, hazmat enviornments, energy pipelines, etc. They have tracked systems for custom applications and can run on diesel generators, as I recall.

Shawn