cutting stainless steel tank - best cutting approach?

[JDanielBryant]

The key to cutting stainless steel is avoid high speed - slow is the way to go when either drilling or sawing. 316 SS is relatively soft when compared to other steels, but if you heat it up at the tool/workpiece interface it becomes a real SOB and will dull the blade/bit you are working with in a heartbeat. I find it best to run a drill press on the lowest speed or pulse the trigger on a hand-held drill. I avoid saber saws as they are tough to regulate speed on. It sounds crazy, but try a hacksaw with a fresh carbide blade - it is easier than you think. Hey, that PhD in Metallurgy comes in handy now that I'm retired!

[captlloyd]

You might try a double cutting saw, they have carbide blades and will cut through about any metal. They are very similar in use like a SkillSaw. Home Depot has them and Harbor Freight also. Do a search on Amazon and learn on YouTube. They have double blades that rotate in opposite directions. I have one. If you can get a piece of sheet metal in between the hull and tank a plasma cutter will make short work of the job, East Mfg. has about the most inexpensive. They don’t put out a lot of heat and with a little water under the hull with a metal barrier you should be fine.

[Cpt Mark]

Plasma cutters are fast to use and really quite easy. But I can't imagine you not causing tons of damage to the fiberglass as you cut. In other words, do not use a plasma cutter.

[Brewgyver]

Premium metal cutting sawzall blades will work, it wet. You can use any light oil, but even water with a bit of dish soap in it will work wonders. I've done a fair amount of cutting SS kegs and other vessels to fabricate brewing equipment. If you need a starting point, use a 1" or so bimetal hole saw, run at low speed with high pressure (pushing the drill motor) and oil or water for cooling.

[Wulf]

Originally Posted by Cpt Mark

Plasma cutters are fast to use and really quite easy. But I can't imagine you not causing tons of damage to the fiberglass as you cut. In other words, do not use a plasma cutter.

X2 against anything flammable. Quality cutting discs on an angle grinder are far more controllable. I have a plasma cutter, would not consider using it for this.

[Squanderbucks]

For whatever replacement tanks you decide to use I recommend plastic for gas and fiberglass or plastic for diesel. Aluminum is second choice for either but harder to remove later for similar reasons to the SS - but less so.

Also SS sweats a lot more than anything else (condensation) with FRP being the best in that regard.

[Titti4]

Definitely an angle grider with discs for stainless. Will cut easely. You could turn the weelguard to lean against the the steel so you don't slip though and cut in the hull..

[Compass790]

Plasma cutter is the easiest/quickest if you can hire one. Next I'd go for skinny discs in angle grinder as others said. You can cut it with a jigsaw but it needs to be a variable speed one so you can slow it down & use masses of cutting fluid. That would be a last resort tho.

[Oceanride007]

I did it to my Large SS water tank, had to do it in strips, already had tools but they were 2000klms away so needed tools that were different. Chose 18V Multi tool, bought individual heads for saber saw with different blades to try out, also got 18V Angle iron, with skinny ss cutting blades.

Of course also get ear muffs and if you cutting fuel tanks make sure they are gas freed.

[Woodland Hills]

This will not help in your specific situation, but SS can be easily cut in a bandsaw with a dull blade. An ancient machinist showed me the way many years ago: using a dull blade hold the SS against the blade as it heats from dull red to cherry to white hot at which point it cuts the metal like butter. The hundreds of teeth on the bandsaw blade keep any single tooth from getting too hot while the metal is friction cut. I didn’t believe it until I saw it, but afterwards I used that technique all the time.

[sailingchiro]

Angle grinder with thin cutoff like most others have said. Both are cheap, you will make a mess and expect sparks. Wet towels seem to work pretty well at protecting everything and your self.

[rmlarson1098]

Originally Posted by tworail

I'm in the middle of replacing both fuel + water tanks in my boat. Both were original installed 1979, in Taiwan. I have fully removed the fuel tank which after a bit of trial and error a high quality Milwaukee sawzall blade was the most adept at cutting through the mild steel.

However on the stainless tank, this blade dulls in seconds and doesn't seem viable for removing a 200 gallon tank with lots of baffles. I did investigate picking up a second hand 10 gauge nibbler, but that is about $300-400 for a tool I may not use frequently, although I could resell it.

Any magical sawzall blades I could try? I'm also not close to a Home Depot so 'running into town' to try something else isn't feasible. I think the latest one I was going to try was a carbide dipped 'Diablo' blade.

Like the man said, cut-off wheels (1/16") and a 4-1/2" angle grinder. You'll need LOTS of wheels. A Metabo grinder is the best, but if you can't find that at least a Makita or another quality brand. If you 'hog' the tool - put too much pressure on it when cutting - you'll probably need more than one grinder. Best to have a back-up grinder anyway, let one cool down while the other one works.
Wear real safety glasses AND a face shield. It's not uncommon for these wheels to come apart at very high rpm. An old welding hood with the clear lens in place but without the dark lens works well also. It's gonna be very noisy; ear plugs or better for hearing protection. I'd wear a respirator. Once you get a feel for it and make your first cut completely thru, you'll be amazed at how well it cuts. Draw the wheel back & forth with moderate pressure on your cut-line till it cuts thru, (you'll know!) and go. Don't tell anybody, but when I do this stuff (and I do a lot of it) I get rid of the handle on the grinder, and (gasp!) the guard. In a confined space both are a PITA, but if you haven't done a lot of grinding better at least leave the guard in place. Wear gloves, (thick ones) and use both hands to hang onto that tool! No one handed grinding or cutting.
Actually for a S.S. diesel tank that big I'd probably use a plasma cutter, after purging the tank completely. But plasma cutters are fussy if you're not skilled with them. The grinder and cut-off wheels will do just fine. Just be careful.

[seabear2]

Not advice on how to cut but rather how to be safe. Use all appropriate protective gear for eyes and extremities and ALSO have a good or two fire Extinguishers close by! Be careful be safe. Good luck!

[BigNash]

You might try carbide tipped sawzall blades.

[Madehn]

i have almost every tool mentioned here-- occilating tool like a Fein will not work well on this task- plasma cutter will work but be sure you have liability insurance paid up and a quick way out-- best response i saw was this--"ike the man said, cut-off wheels (1/16") and a 4-1/2" angle grinder. You'll need LOTS of wheels. A Metabo grinder is the best, but if you can't find that at least a Makita or another quality brand. If you 'hog' the tool - put too much pressure on it when cutting - you'll probably need more than one grinder. Best to have a back-up grinder anyway, let one cool down while the other one works.
Wear real safety glasses AND a face shield. It's not uncommon for these wheels to come apart at very high rpm. An old welding hood with the clear lens in place but without the dark lens works well also. It's gonna be very noisy; ear plugs or better for hearing protection. I'd wear a respirator. Once you get a feel for it and make your first cut completely thru, you'll be amazed at how well it cuts. Draw the wheel back & forth with moderate pressure on your cut-line till it cuts thru, (you'll know!) and go. Don't tell anybody, but when I do this stuff (and I do a lot of it) I get rid of the handle on the grinder, and (gasp!) the guard. In a confined space both are a PITA, but if you haven't done a lot of grinding better at least leave the guard in place. Wear gloves, (thick ones) and use both hands to hang onto that tool! No one handed grinding or cutting." i think he said it best. have the fire extinguishers clsoe and dont be alon when you do it so that if something goes wrong there is somebody to help also really good advice to have a couple of extinguishers close