Cutting bolt with minimal heat

The guy has a steel boat that had a wooden (teak) deck installed on it. These decks are normally about 1/2" thick and held down with about a million sheet metal screws. Water eventually leaks under the wood and corrodes the steel deck.

The guy has removed the old rotten wood and now has to seal all those screw holes BUT the underside of the steel deck is sprayed with (probably) 2 inches of foam insulation that he doesn't want to dig out or weld near. As soon as he gets the holes filled he plans on sandblasting the deck to "white metal" and priming with (again probably) epoxy primer and then fill, fair and finish.

How to fill the holes?

Bruce-in-Bangkok (Note:remove underscores from address for reply)

That would work, if you can still find the real stuff - AIUI the enviro-nuts don't like it anymore because of the phosphates in the waste water, and the substitutes aren't.

Procedural note - Roy, if you want aggressive alkaline cleaning you want 'automatic dishwasher detergent' like Cascade, not 'laundry detergent' like 'Tide'. If you tried doing your laundry with something that alkaline, some items would go into the tub as cloth and come out as lace.

-->--

The local 'Do It Best' hardware store has it but you got to be careful not to get the TSP substitute. No wonder it was banned, it works!

Wes

Dead right, in context here. Note that dishwasher detergent doen't get active below 120F. I'm not making this up; I was told this by a P&G chemist.

Thank you all for the reactions. I=B4m quite amazed by this enormous response. Out of all the suggestions I chose to use the grubscrews. I found some zinc plated grub screws, which seems to be a little rare, so I don=B4t have to clean the oil off that is on the normal black oxide ones. What I do after removing the deck with brute force:

1. drill all holes with 5 mm
2. tap 6 mm thread into it with the tap on the battery drill in low gear using cutting oil
3. degrease the holes with carb cleaner
4. dip grubscrew in epoxy and screw in until top side of the screw is level with the deck
5. with a syringe I also fill the hex slot of the screw with epoxy
6. sandblast
7. paint
8. fill the hex slots again with epoxy filler, depending on how much of this was shot out by the blasting
9. paint again

Which is why our "back" water heater is cranked all the way up, around 160F. You have to be careful at the kitchen sink, but both the clothes washing machine and the dishwasher are much happier.

Should go get a couple of point-of-use sized tempering valves for the sinks, but I'm a firm believer in Darwin's Law. The steam is trying to tell you something...

-->--

Okay, now that you have all the holes sealed what are you going to do with the bare deck? Anti-slip paint with silica sand, ground walnut shells or AlOx particles mixed in?

Or make removable floorboard panels that only bolt down at the cross- slats and in the corners? That would be my first thought - they start looking bad every 10 years, pull them up and make new ones.

-->--

I'd weld those holes. If you're worrying about the foam burning, you can tarp the area you're not working on and shoot CO2 in with the foam before working. If it's no big deal to get water under the deck then you can just flood it, no big deal.

John

Have been there and done that. Get a bunch of socket head set screws. Drill and tap the screw holes and screw the set screws in after dipping the screws in epoxy or locktite. Make sure that they are flush. Let them set over night and sandblast the deck. Immediately prime, fill, fair and prime with high build primer. Finish sand and paint with 2 part paint. then apply antiskid of your choice.

An alternate method would be to sandblast and immediately prime. then fill the holes with epoxy filler, fair and prime and finish.

I suggest that the first methow\d will result in the longest lasting repair.

Bruce-in-Bangkok (Note:remove underscores from address for reply)

Well, that=B4s indeed a next problem. I feel most for anti slip paint, but I=B4m still investigating the best way to do it. Many methods are not really good. I heard good stories though about some granite grain made by Sika.

Yes, this first method I will follow. It seems to be fast and good.