Howto put an inspection hatch in an SS water tank ?

[Boo2]

Hi,

Q.a.t. : What's the best way to put an inspection hatch in a stainless water tank ?

The tank in Sunrunner is 115 litres or so and has has no inspection facilities whatsoever. Reading threads about slime build up makes me think adding one is a good idea since it is 35 years old

Thanks,

Boo2

 

[Deleted member 36384]

http://www.tek-group.co.uk/acatalog/Inspection_Hatches.html

Cut hole in tank and drill for top flange bolt spacing.
Make semi circle inner flanges thick enough to stiffen the tank top.
Drill inner flanges with top flange bolt spacing.
Bolt top and inner flanges together with simple neoprene gaskets.
Screw on lid.

Actually the FLB Inspection Hatch in the link, is even easier to install as it only requires one hole to be drilled!

 

[Tranona]

Just having one put in my tank now. 6mm circular plate welded onto tank surface, drilled and tapped to take M6 countersunk allen headed screws holding down sheet SS plate and neoprene gasket. Alternative is to have similar plate to take screw on inspection hatch from TekTanks - bit more expensive but quicker to remove for cleaning.

Not totally convinced it is necessary if you keep a good flow of water through the tank and use bleach to keep clean, but tank is out for repairs and other mods, so easy for the fabricator to do at the same time.

 

[Norman_E]

My boat has two 300 litre tanks with inspection covers. Up till this October I had not removed them because we never drink from them, as Turkish tap water, though safe, is very heavily chlorinated. I had to have the tanks out to repair a leak, so took the covers off. Surprise, surprise, the tanks were quite clean inside with only a few bits of debris that had come in with the water. It makes me wonder how necessary they are.

 

[SHUG]

This might be an option for you:
http://www.007securitycamera.com/ECC-102.htm

Its a fibre-optic inspection camera which may have other uses on the boat.

 

[Boo2]

Thanks for the replies, but can anyone tell me how to put an 8 inch (ish) hole through the top of my existing tank ?

Boo2

 

[Deleted member 36384]

Thanks for the replies, but can anyone tell me how to put an 8 inch (ish) hole through the top of my existing tank ?

Boo2

Scribe the circle using a simple school type compass with something like a CD marker pen.
Inside the circle, near the circumference drill a hole about 5 mm in diameter.
Then with a jig saw, using a blade for stainless, insert it through the hole, and cut out the circle, err on the inside of the pencil line.
Dress off the cut edge with wet and dry after fileing off any burrs.

Use a cloth pad to push down on the tank top while cutting with the jig saw, it will help dampen out any vibrations due to the thinness of the tank top.

 

[vyv_cox]

Thanks for the replies, but can anyone tell me how to put an 8 inch (ish) hole through the top of my existing tank ?

Boo2

Or as an alternative to a jigsaw, which I find not the easiest tool to use on unsupported sheet steel, you could use a nibbler like this. Mine will cut steel of typical tank thickness fairly easily, although some hand strength is needed. Its big advantage is that it doesn't create any swarf.

 

[Norman_E]

Or as an alternative to a jigsaw, which I find not the easiest tool to use on unsupported sheet steel, you could use a nibbler like this. Mine will cut steel of typical tank thickness fairly easily, although some hand strength is needed. Its big advantage is that it doesn't create any swarf.

You may need a better one than that for stainless. I have one (different make) that is rated up to 1.5mm in "metal", but that actually means sheet aluminium, for mild steel it works, with difficulty, on steel about 0.8mm thick, and stainless would have to be thinner than that for it to be any use. I have seen power nibbler attachments that fit a drill, and they are capable of cutting stainless up to about 0.8mm, maybe a bit more, but they produce a shower of small punchings. The stainless tanks on my boat are about 1mm thick.