Fuel tank inspection hatch

prv said:
Depends what we mean by "plastic tank". A welded 10mm polyethylene tank as made by Tek Tanks will work very well with the FLB clamp-on hatch. A thin roto-moulded tank probably not. A stainless steel one I'd expect to be a bit marginal due to flexing. Not sure about aluminium as I've never had an ally tank and not sure how thick they typically are.

Since it's not the sort of thing you need to open in a hurry, I reckon a simple ring of bolts and drilled plate, in the same material as the tank, is the way to go. It's what I did on mine.



If the tank's sitting in the bilge, I doubt there's room to have an agglomerator below it.

A closer equivalent to the gravity drain would be a second pickup tube reaching right to the bottom of the tank, whereas the normal fuel supply one stops an inch or two above it. Then a pump can be used to suck out any water and loose crud in the same way as the traditional drain cock. Might be worth making the tube a size or two larger than the supply one, to prevent blockage.

Pete
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Yes - a bolted plate is where I am going with this, and yes the tank is way down and no space to put a drain even if you could reach it, which you cannot. But another tube to suck out the gunge - now that is a good idea.

Thanks
 
pmagowan said:
You would be surprised what apparently sane people do. Yes, using a cutting torch would be silly and ineffective but many people use angle grinders and other tools that can get very hot very quickly on tanks. I don't think a word of caution is unwarranted, I did not give a lecture, and much of the detail has appeared after my post. Simply put, you should always take care when using power tools on a metal tank that has contained a volatile substance. Explosions can and do occur and preventing them is incredibly easy, requiring, as you say, a simple flush-out. I am not sure why the matter requires any debate or further comment, just a simple bit of advice.
Click to expand...

No worries with this. The tank will be on my bench having been emptied and thoroughly flushed with water.

Thanks for the concerns
 
vyv_cox said:
If you mean the type of hatch that people fit in cockpits or on the buoyancy tanks of dinghies I suspect you would have to be very careful about selection of any seals or O-rings. They are likely to be EPDM, which although excellent at resisting water and UV, are hopelessly non-resistant to hydrocarbons.
Click to expand...

Thanks for this. I did wonder if they would be suitable but, for the reasons that you have given, it seems not

Thanks again
 
One of the PO's installed this type on our diesel tank http://www.wema.co.uk/pg_FLB-1.htm

After we fixed the fuel filler we discovered that it leaked (first time we managed to fill the tank to the brim, and going out in real choppy waves with a topped up tank)
The reason for this was that the access hole was cut across baffles that where welded to the tank top creating a small depression/dimple in the tank top.

looked at a similar solution to this http://www.seabuilt.com/demo.php (I think this is a good design - you could make something similar your self, it's easy to make)
But found we found that it would not work for us due to the hole going across the baffles...

This is made out of three parts in SS plus three gaskets
The inner ring is cut in two halves to fit both side of the baffles, with an oil resistant rubber gasket between the inside of the tank.
The bolts to secure the lid is screwed into tapped holes in the inner ring and there are also tapped holes for he fixing bolts for the lid (seen in the picture)
Rubber gasket between the outer ring and tank top.
Lid is screwed down with gasket, spring washers and nuts.

D5888377-0ABB-45BC-A57D-81827A4F7385_zpsumy5nuf1.jpg


We pumped out the content of the tank before starting to drill and cut with a jigsaw to adjust the size of the hole.
We discovered the the PO had not bothered to remove the cuttings when he cut the initial holes..
After we where finished with drilling and cutting we disconnected the fuel line, washed with warm soap water using a wet vac to remove the soapy water and metal cuttings, flushed with warm water several times.
Let he thank dry before connecting the fuel line and pouring the diesel back into the tank using funnel with filter (mr. funnel)

Old and new
FF933401-5140-4875-B351-31E78E2AD7E2_zps6pfjp8e2.jpg
 
The best tool for cutting the hole is a 'reciprocating saw' works really well, no heat to speak of, cut my steel fuel tank easily and faster than a jigsaw.
 
I have aluminium quick release covers on my distributed tanks. I can't remember the name (age!) but I'll have a look later.

They have a bar across the top with a lever operated off centre cam in the middle. Lifting the lever enables the bar to be removed.

Thinking they were well known and ubiquitous, I have waited for someone to mention them.

I think it began with an "H".

It does - Henderson. Google it.
 
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donm said:
Thanks for this. I did wonder if they would be suitable but, for the reasons that you have given, it seems not

Thanks again
Click to expand...

You seem to have been faced with equal number of negative posts as helpful ones.

Walkers have eminently suitable 'Lion' jointing material for this application.

If you make hatch oval all you need is a corresponding stainless steel reinforcing ring with welded studs which which you slip through your hole from the inside, drop your jointing on then fit perspex lid with nice ample stainless washes and torque it down. Makes a nice robust joint.

Have no time for our current safety obsessed culture, H&S people always tell you what you cannot do but rarely provide alternatives work practice. In my workshop in Africa trucks had to be turned around fast, leaking diesel tanks were often mig welded up with truck loaded and ready to roll even with the engine running, worse incidents were a couple cases where fitters suffered sudden loss of eyebrows. 50,000 liter road tank trailers imported from the UK, ex Shell were clapped out and always leaked in area of 5th wheel mounting resulting in gas oil all over the rear bogie. Tanks drained and steam cleaner run in the inspection hatches for a couple of hours before welding up, Institute of Petroleum would have had kittens, however we never had incident like Buncefield.
 
donm said:
I need to get inside my fuel tank to clean it, check the connections/pipework, and maybe install a dip meter. The tank is aluminium and completely sealed, and has tapped connections for inlet and return, spigots for filler and breather, and no other way in. Because it is in a deep bilge (Halmatic 30) it is a purpose wedge shape, is in good condition but takes some getting out. What I would like to do is fit a removable hatch to the top so that I can clean it without removing it. I thought maybe a plastic screw hatch bolted and bedded?

Is this type of hatch safe with diesel/ is this a good idea/anyone else done this?
Click to expand...

Bump
I have cleaned the tank and cut the hole for the hatch. Everything clean in the tank and no delivery problems in the pick up pipe. So, I have replaced the filters and upgraded to Racor, renewed all delivery pipework and purged the tank. The last possibility (intermittent stopping) is fuel starvation because the lift pump is not able to do the job. Max lift is in the order of 1.2 m and min is around .6 m so both well in excess of the .25m recommended by Beta!

A small electric lift pump looks to be the solution. Has anyone else fitted one - there are plenty to choose from on fleabay?
 
Continuing a similar vein: I just removed the inspection hatch from my Moody 31. All metal (mild steel, I think). The gasket was 2 layers of cork with some very obstinate black gubbins to glue it all together. It took me a good 30 minutes or so to get it off.
Are there more suitable gasket materials? I was thinking of cutting some thick polyethylene sheet (like a large milk flagon) to provide a couple of layers. Maybe a thin PE chopping board? I assume that would be better than neoprene sheet. Then perhaps a thin layer of blue gasket to seal?
 
lampshuk said:
Are there more suitable gasket materials?
Click to expand...

I just bought a sheet of nitrile rubber off eBay, from memory probably 3mm thick. Bolted down down nice and tight between the lid, the tank surface, and the reinforcing ring inside the tank, it's never shown any sign of leaking.

Pete
 
lampshuk said:
Ah yes. Sounds like a plan. Have you removed it? Any issues with it turning to glue?
Click to expand...

I've only had it for six months or so. But nitrile is used for pump diaphragms and other rubber parts in long-term contact with diesel, so should be fine. Don't just use any old unknown rubber sheet you have lying around.

Pete
 
lampshuk said:
Continuing a similar vein: I just removed the inspection hatch from my Moody 31. All metal (mild steel, I think). The gasket was 2 layers of cork with some very obstinate black gubbins to glue it all together. It took me a good 30 minutes or so to get it off.
Are there more suitable gasket materials? I was thinking of cutting some thick polyethylene sheet (like a large milk flagon) to provide a couple of layers. Maybe a thin PE chopping board? I assume that would be better than neoprene sheet. Then perhaps a thin layer of blue gasket to seal?
Click to expand...

Several products similar to this - http://www.stationaryengineparts.com/Heldite-Jointing-Compound.html
 
lampshuk said:
Continuing a similar vein: I just removed the inspection hatch from my Moody 31. All metal (mild steel, I think). The gasket was 2 layers of cork with some very obstinate black gubbins to glue it all together. It took me a good 30 minutes or so to get it off.
Are there more suitable gasket materials? I was thinking of cutting some thick polyethylene sheet (like a large milk flagon) to provide a couple of layers. Maybe a thin PE chopping board? I assume that would be better than neoprene sheet. Then perhaps a thin layer of blue gasket to seal?
Click to expand...

Cork remains one of the most effective gasket materials. It is actually cork particles bound together with an elastomer, which for fuel would usually be nitrile rubber. It is usually available from motor factors. One of the required properties of a gasket is that it should deform to accommodate any roughness of the surfaces. Your polythene or HDPE would not be very effective and very likely leak.

My new fuel tank sender unit came with a cork gasket.
 
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vyv_cox said:
Cork remains one of the most effective gasket materials. It is actually cork particles bound together with an elastomer, which for fuel would usually be nitrile rubber.
Click to expand...

Genuine question - what benefit does the cork provide over using just the rubber?

Pete
 
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