vic008
Well-Known Member
Wish to cut out an inspection port in my SS diesel tank. What is the best way to guarantee a leakproof seal. Have some 3mm SS plate, and taps and dies.
Diesel tight seal in SS
- Thread starter vic008
- Start date
vyv_cox
Well-Known Member
Nitrile-bound cork gasket. Available from most automotive shops but of course also on-line.
Plum
Well-Known Member
As Vyv says, but in my experience the tank will be made of 1mm or less material thickness so will distort and not adequately clamp the gasket material between the screws so may leak. If your tank is thin walled suggest you use some of your 3mm stainless in 25mm wide strips to fit inside the tank to screw into. Ideally you could use M4 stainless countersunk rivnuts 40mm apart that are inserted through both the tank and the 25mm strips. My standard pop rivet tool has an M4 mandrel to set the rivnuts. You will also need some soft copper washers under each screw head.
M4 - 4mm RIVNUTS COUNTERSUNK STAINLESS STEEL THREADED RIVET NUTS INSERTS NUTSERT | eBay
Www.solocoastalsailing.co.uk
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vyv_cox
Well-Known Member
Not sure if inspection hatches come with a C-shaped inner support. My fuel depth sender has one, it can be inserted into the cut hole and solves the problem highlighted by Plum.
CJU
Well-Known Member
When we had to have our polythene diesel take cleaned the engineer used a tank cutter to cut a approx 6” hole and then fitted an all in one hatch. I’m not sure where he got it from but must be easily available. So far it has remained fuel tight.
Sorry I can’t attach the photo but it it is hard plastic and has a hatch lid with large O ring seal, central bolt an d a large C ring backing plate, which goes behind the plate inside the tank. Chris from the clean diesel company did the work.
Sorry I can’t attach the photo but it it is hard plastic and has a hatch lid with large O ring seal, central bolt an d a large C ring backing plate, which goes behind the plate inside the tank. Chris from the clean diesel company did the work.
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PTB
Well-Known Member
'it it is hard plastic and has a hatch lid with large O ring seal, central bolt an d a large C ring backing plate'
This sounds like the Tektanks FLP inspection hatch .. they have a video of how to fit it somewhere on their website. It has been perfect on our plastic water tank, but I'd be a bit wary on a thin metal fuel tank. Fixed stiffener underneath and plenty of fasteners would also be my choice. Oh yes, (through bitter experience) check where / if the tank has a baffle !
This sounds like the Tektanks FLP inspection hatch .. they have a video of how to fit it somewhere on their website. It has been perfect on our plastic water tank, but I'd be a bit wary on a thin metal fuel tank. Fixed stiffener underneath and plenty of fasteners would also be my choice. Oh yes, (through bitter experience) check where / if the tank has a baffle !
Klausen
Active Member
Vetus ILT120?
vyv_cox
Well-Known Member
Looks like a clever bit of kit that copes with all tank materials and contents.
Forty_Two
Well-Known Member
Will just Nitrile sheet material work as well as the compound material?
captainboo
Well-Known Member
The nitrile sheet by itself is relatively hard and as such won't seal as well unless they are parallel, close fitting and fairly imperfection free. It would also need a larger number of fixings to ensure an even and highish clamping force across the seal area.
When I did mine on my stainless steel tank I put rivnuts into the tank surface to bolt to, about 12 for a 12" diameter hatch. The gasket was 3mm thick cork/nitrile and I also used Loctite 5922 flange sealant (available from Halfords) to guarantee it leak free. Has worked perfectly for the last 10 years with no weeps/leaks.
jwilson
Well-Known Member
Sealing a new hatch into a diesel tank made of slightly flexible materials is an utter swine. My bitter experience is with a rotomoulded plastic tank, but a thin-wall S/S tank can't be rigid enough to be much different. If your tank is thick-walled and rigid it's probably easy enough. Cork/nitrile and Hylotyte or similar sealant gives the best chance of sucesss. Have had gaskets supposedly made of plain nitrile degrade and go soft/sticky.
DownWest
Well-Known Member
Slightly off the wall.. But why not cut an oval hole, then cut an SS plate that overlaps the hole by 10mm or so, in 3mm plate. Then cut another similar one. Use a central bolt to close them up on the cut out in the tank with two gaskets so you can wind up the bolt to put pressure on the joint. Prob less work than trying to put lots of rivnuts or C bits in the tank. (oval, so you can easily put the one in the tank)
DW
DW
Oily Rag
Well-Known Member
This thread seems to be converging on the design of a traditional internally-sealed oval boiler manhole!
penfold
Well-Known Member
To ensure a leak free hatch I'd be inclined to not have the fastener holes penetrate, but that means welding a prepared flange onto the opening so not very helpful to the OP.
vic008
Well-Known Member
Thank you all, Do like the Vetus ilt120. But dont understand the instalation. If I say manhole covers are circular so they cant fall in, that probable conveys my misgivings best.
Can they be installed from the top?
Can they be installed from the top?
Wing Mark
Well-Known Member
The best way to guarantee no leaks is not to go cutting more holes in a perfectly good stainless tank.
Use an endoscope to inspect it via the holes you already have.
Second best might be a Viton O-ring clamped by a properly designed structure.
Large flat gaskets are risky as you need many fasteners and lots of force to ensure proper pressure in the gasket, and few materials are really reliable in contact with fuel permanently.
If every part of the gasket is not under pressure, then you cannot be sure there won't be a gap where the surfaces don't stay perfectly flat.
If the material loses its elastic properties over time, then any movement may result in a leak.
It's possible you could use a sealant, one of the Hermatites used to be OK for diesel, gold maybe?
But the chemistry of diesel may not be exactly like last century....
oldgit
Well-Known Member
Beware any swarf or any instant gasket type material finding its way into your tank.
It might take months or years but it will find its way back into your life eventually.
It might take months or years but it will find its way back into your life eventually.
ean_p
Well-Known Member
Though the hole will need to be cut with some accuracy depending upon the flexibility of the sideways expanding seal.....
Plum
Well-Known Member
Yes, fitted from the top with nothing larger than the hole needed to be inserted. The hole needs to be accurately cut to size and smoothed. Drop the whole assembly in and when you tighten the screws, which do not go through the tank material, the rubber sleeve expands and locks against the underside of the hole. There appears to be just one small screw that goes through the flange into the tank to stop the whole thing from rotating when screwing the big cap off and on.
www.solocoastalsailing.co.uk
vic008
Well-Known Member
Vetus ILT120 Have purchased, but cant work out what to do with the rubber seal. Watched the youtube and not shown at all, instructions no clearer. Any help please. Do I remove the 4 screws and disassemble it
