Weeping Fuel Tank Seal

[Stoaty]

I have two fuel tanks installed on my boat but they are built as one tank. Total 360 Gallons. They or should I say it, lays athwartships in the centre of the boat. There is no access to the top as its right under the deck. There are inspection panels in the front of each tank. They are quite large, you could probably get your head and shoulders in them. I will shortly be finding out. The seal on the starboard panel is weeping. Not seriously, if you wipe the drip away it will take some hours to reappear. A bit quicker if the tank has more fuel in it. Down to the pressure I would assume. If you look at the pictures below you will see that the seal is made of some kind of rubber or nitrile material that has squeezed out in the right hand bottom of the inspection panel. The seal on the port side is going the same way in the same corner but is not leaking yet. When the fuel level is low enough to allow me to replace the seal, I am minded to get a cork one made as I have only seen cork seals on fuel tanks before. I feel this rubber nitrile material is not suitable for these conditions. I would like to know what the forum think and how you would deal with this.

 

[Frontier]

I wonder if this would fix it? it says its good for diesel.

Plastic Padding Leak Fix

No doubt the the forum will have a view.

Good luck

D

 

[Peanuts]

Hi
On aircraft we use a sealent called PRC1422, it seals everything, most fuel access panels will use this compound. However in your case I don't believe it is the seal that is the cause but probably the corrosion between the panel and the seal. So I would remove the panel to see if it can be cleaned up, together with the edge of the tank and manufacture a new rubber seal and try it again because up till now it has been ok, hasn't it?.
If all else fails use PRC but hope you never have to remove the panel.
Hope this is of some help.

Steve

 

[Scarron]

Depends entirely what the original seal material is; I am assuming that from the type of boat that your fuel is Diesel? if so, yes you should be using a Nitrile seal, from the pic it would appear to be pretty swollen suggesting the existing seal is either Natural[no fuel resistance] or Neoprene [some fuel resistance]. Unleaded or especially Super-U may require going to a more expensive option such as Viton.

Ideally in this application you need a good specification Nitrile [i.e. conforming to BS:2751]with a good level of Acrylonitrile-Butadiene rather than a commercial spec or if you prefer a Nitrile based rubber/cork gasket, it may be more appropriate if the sealing flange is narrow.

PM me some dims for the gaskets and I'll see what I can do to help.

Paul.

 

[Stoaty]

I think the tank is in a reasonable condition. It's heavily made from 3/8" steel. The panel is ¼" steel. It's my intention to clean it up and paint it when the seal is done. Corrosion is only on the surface where the diesel has leaked and lifted the paint. On the port side the tank is clean with no corrosion. Each tank has it's own sump and drain tap, which I check every few weeks. I normally get a small amount of water and clean fuel. No sign of internal rust.

I have about ½" of fuel to burn off before I can safely remove the panel and pump out the remaining fuel. So it will be a couple of weeks before I can get it off.

According to the paperwork that came with the boat. The tanks were inspected in 2004 as part of it's small commercial boat certificate and new seals were fitted. I suspect they are of the wrong material.

Thank you scarron for the information about the specification of the seal material. I have only ever come across cork seals in this type of application. Would you use any type of sealant with a new seal?

 

[nedmin]

Have word with Marine and Industrial Sealants. Tel 01692 406822 they should be able to help. you will have to get rid of all the rust where the lid fits .