I have a plastic central heating oil tank which has developed a thin crack where the curved top meets a horizontal surace about half way down. The tank is not leaking.
Can anyone recommend a product for fixing this crack?
I doubt if there is anything that will stick to a plastic oil tank well enough to work. Is it a double skinned bunded tank or single skin?
IOW if it fails completely will you be paying for oil clear up?
Possible a patch of a similar material as the tank and solvent based cement/glue that actually dissolves the surface of the plastic and "plastic welds" it together.
See also youtube videos on plastic welding (car bumpers etc.) using heat and plastic welding rods
Picture?
Does no leak mean it is double skinned, or that it is a crack that has not separated at all, I wonder.
There are wide tape products with a thick sticky back glue (revealed by a tear-off protective layer) that claim to do good repairs to plastic water tanks and pipes. I'd have thought these might be the first thing to try.
My mechanic mate did an amazingly good "weld" repair on the plastic internal structure of a car rear light unit, he obviously had the right "filler rod" because it looked for all the world like a TIG weld in aluminium. But I wouldn't try that myself on an oil tank, too much to lose!
Not worth the risk. Very expensive clean up. If the fuel goes under the house very, very very expensive. The delivery drivers here refuse to fill tanks that are suspect. Get it replaced now while it is warm, not in the rain and dark of midwinter.
I'd say there is not enough information presented here to make that decision.
I would say replacement should be considered, especially where the crack is 'half way down'.
If it can be repaired in situ with confidence then maybe. The risk and cost of it going wrong are too great to contemplate.
Why isn't it currently leaking? Because it is a twinwall tank, or because it is not an effective through-wall crack. Is it a new crack, is it propagating, or is it perhaps a tolerable manufacturing defect. How old is the tank. Is it bunded? How much oil does it contain. How affluent is the OP, and how risk-averse?
The consequences of failure could be very severe, or perhaps not so serious. But you also have to assess the probability of failure to quantify the risk and do a cost-benefit analysis.
To repeat, the OP has not provided sufficient information to do any serious assessment.
Normally if its a single skin tank the crack will gradually propagate through the plastic since the oil pressure inside is pausing the plastic out. Even if you stick a patch on it, because its still slightly pliable you are only delaying the inevitability. Time though to put an oil catching plastic sheet or something under it. I'd imagine. But then this time of year is the ideal time to replace it I'd have thought. If its relatively new you might have a case for some discount on the next one. I well remember a tank of ammonia made of plastic where I worked cracking like this. You do not want that sort of chemical to leak I can assure you, we were smelling it for bloody weeks! Brian
Sadly if it really is a crack, I cannot but agree. Bite the bullet and replace it
I rather suspect the decision will be made by whoever refills your tank. The rules regarding what is acceptable in terms of tank condition are pretty strict and whilst a repair might seem fine, it?s not your decision as to whether the tank is still usable.
Tim
The big risk is that it will suddenly start to leak much more seriously shortly after you have had a full delivery of oil due to the pressure.
Cracks tend to propagate and once started ingress of moisture will speed things up. Methanol would speed things up even more. Stress corrosion cracking of plastics is somewhat unpredictable but once it has started the end point is more or less inevitable and accelerating.
Thank you for the link.
I don't know the age of the tank as it was there when we bought the property. It might be the same are as the boiler which dates from 2000. It has faded in the sun. The cracks are not obvious and may have been there for some time.
Elsewhere I have a 600 gallon steel tank which has been fine since I installed it in 1986 to replace a tank that was rusting. At that location I had a neighbour who had a steel tank that rusted and then leaked. He replaced it with a large bunded plastic tank. After he and his wife died a few years later the property was bought by a developer who knocked the house down and built a new larger one. The only thing he kept was the bunded oil tank which I had been hoping he might not want.
It would appear that Titan have had problems with their tanks failing:
If that was intended to be a link, try
Ooops bad mistake.
That's a clue. Apart from uPVC, plastic items should be protected from direct sunlight (and UV light) if they are outdoor permanent fixtures. Needs to be surrounded by some fence panels with climbing plants or hidden behind some laurel or similar to provide shade.
In the UK the OFTEC regulations for liquid fuel tanks do not permit such screens close to the tanks.
In fact when i had a new oil tank recently i had to remove such wood fencing and vegetation close to the tank site before the change.
Oil tanks are supposed to be made of UV stabilised exterior grade plastic although there is some debate about just how effective it is longer term. I reckon some embrittlement from sunlight and winter freeze thaw action on scratches is inevitable for a tank that is outdoors.
My old metal tank was quite literally held together by many layers Hammerite when I replaced it because of a trace leakage at the base. The guy who put the new one in thought it looked OK to him until he tried to lift it and the top came away at one end leaving the base on the ground.
I will be checking mine carefully after this thread.
Mine is a fully bunded double skin tank due to proximity to a well and a beck. No signs of any noticeable fading as yet and it is a couple of decades old. OTOH it isn't much in direct sunlight either.
IN that case, can they be painted with solar reflective paint ?. The sort used on bitumen flat roofs ?.
I would be very careful about doing anything unusual to it that might compromise the material in any way. Low molecular weight highly polar solvents in paint like methanol can be incredibly damaging.
Lime wash as used on greenhouses might be benign enough or it might not. I wouldn't chance any kind of classic paint formulation on it though.
Mine seems happy enough as it is. The top gets the direct sun at times and shows no sign of discolouration after 15 years.
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