mild steel diesel tanks.

On our Parkstone Bay, built 1975, (38 years) we have the original MS tank. Internal corrosion, I suggest, is best kept at bay by keeping the tank full, especially in the winter. External corrosion is probably a question of routine maintenance when the builder-supplied paint is damaged. Now, here's a question - when to replace? Answer is in fact easy - the winter before it rots through and dumps 60 litres of diesel in your bilge. Supplementary (difficult) question - which winter will that be ??????????????????

Best regds

Andrew
 
I fancy a plastic fuel tank but Tek-Tanks want the thick end of £900 !

They are definitely having a giraffe and definitely not having my cash. I can get a stainless steel one made for a third of that.
 
fisherman said:
TekTanks will tell you condensation is not a problem. Their website is no help with sauce for a guinea fowl, however.
Click to expand...

I can confirm that Tek Tanks will be quite safe to use with any sauce you may choose to accompany a guinea fowl. You might want to clean the tank out if it has already been used though, some tanks more thoroughly than others...
 
wully1 said:
I fancy a plastic fuel tank but Tek-Tanks want the thick end of £900 !

They are definitely having a giraffe and definitely not having my cash. I can get a stainless steel one made for a third of that.
Click to expand...

To replace my tank exactly is over £2k. Have you checked out the stock tanks in the 'online shop' section? I found two tanks that should fit for less than £500, plus £20 per fitting.
 
An old boat of mine the mild steel tank lasted 20 years before it rusted through from the top where seawater had sat on it.

I replaced it with a new mild steel tank blasted and painted with a sump of about 2 litres and a drain valve to strip water and crud.

There can be issues with large stainless tanks in fast motor boats as generally the sheet is thinner than mid steel and with the welds not as good but in a yacht for a small tank no problem, materials cost more but labour is the same, less if you include painting the mild steel tank.

There are issues with aluminium fuel tanks being corroded from the inside with diesel bug.

Interestingly when I quizzed Tek Tank about using their tanks for diesel they were very cagey?

I would commission a steel painted tank or stainless tank, ensure that it has a sump and either a drain valve if you can easily get to it or a stripping line to the bottom of the tank sump so you can use a Pella vacuum oil pump to strip the tank of water and crud.

Depending on how long you intend to keep the boat.
 
the problem is no matter how hard we try to keep to keep moisture out of our tanks over the years it gets in. the fuel floats above the water allowing the water to.. all be it slightly...corrode the bottom of tank. rust can contaminate the filter very slightly. the point i am making is if you can afford 316 stainless go for it.
i appreciate some owners have had 20 plus years out of mild steel and that's great but a lot have had lots of head aches. hey just my point of view. garry
 
wully1 said:
Even if I find one for £500 that is still double what I can get a stainless steel one for - custom made....
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Then you have found an unusually cheap source. On the two occasions I have fitted custom tanks there has been little difference in quotes between stainless and Tek Tanks.
 
chaldon3 said:
the problem is no matter how hard we try to keep to keep moisture out of our tanks over the years it gets in. the fuel floats above the water allowing the water to.. all be it slightly...corrode the bottom of tank. rust can contaminate the filter very slightly. the point i am making is if you can afford 316 stainless go for it.
i appreciate some owners have had 20 plus years out of mild steel and that's great but a lot have had lots of head aches. hey just my point of view. garry
Click to expand...

I have something of a theory that the conventional method of drawing fuel from a tank through a dip tube contributes to the corrosion. Water that lies below the fuel is rarely drawn off and accumulates until it becomes damaging, in addition to providing ideal conditions for diesel bug growth. When steel central heating oil tanks were still around it was normal to install them with a slight slope towards the nozzle, which was always at the bottom of the tank. This allowed any entrained water droplets to be drawn out and burnt before they could do any damage. I have had two steel central heating tanks installed like this, both of which corroded through from the outside due to standing water on the supports. In each case the inside was bright and uncorroded.
 
Mine is 19 years old, i took it out, it had some rust on the base so i cut the bottom off it. Only to find the rust was only on the surface. The sides and top were good so I had a man weld in a new base for £40.00. A few coats of paint and it should last another 20 years
 
don't understand why new tanks are not fitted with a low point sump to allow the water to collect. We have this at work in refinery tanks. We draw the water off from the sump which is more effective. It corrodes so generally needs replacing at overhauls circa 20 years but it leaves the rest of the floor fine. If you can epoxy coat the inside of the sump then it should last much longer. We now coat the inside of the sumps with an international spec epoxy paint for that reason and it works!

If you can get access from a decent top hatch and you can clean it, you could patch it externally, repair the pitting with epoxy then paint the floor and side walls for about 150 mm and it should last for the same again.

May save someone a new tank plus the hassel

If you have an old tank may be worth repair and modification on a bigger tank as the rest is probably fine.
 
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