One of the questions I am frequently asked when inspecting boats, particularly older ones, is “Can I repair old tanks if I don’t want plastic or stainless steel instead?” Well of course you can, but you just have to get the job done right because the last thing you need is a fake job leaking fuel or water everywhere, filling up the bilges. The top priority, of course, is safety issues and you can be sure that if there is a fire or damage due to leaking tanks, your insurance will almost certainly be considered null and void. In many cases the tank will be beyond redemption, but the tank may well be used to allow a new tank to be molded from the old one, depending of course on your own GRP skills and the free time you have to spend. do it. in.
There are several stages to tank repair and certain criteria to consider before starting the job at hand. Fuel tanks have a different function than water tanks, but repairs to both must be adequate, safe and sturdy. Materials must also be considered and a decision made as to whether the repair can be considered economically viable, although in most cases the price of a new tank is quite high.
DAMAGE ASSESSMENT
One of the questions that needs to be answered quite early in the article is ‘Will it be an internal repair or an external repair?’ Naturally, the job may well make a difference if the inspection panels can be raised immediately to allow access for repair. The other critical question is. ‘Where is it leaking and how bad is the damage?’ This can be extremely complicated and often very misleading. A small leak from a puncture in the rim of a tank can run several feet along pipes, down slopes, and grumpily drip somewhere quite different, giving you a bad head! The problem can be aggravated by rain or pipes leaking from above, giving the leak an added dimension. Worse yet, and most unfair, a tank can leak from several places at once, but come out downhill in a very different place! Beware too, the flange leak or faucet leaking undetected along the pipe, below the bottom of the tank, giving the misleading impression that the problem is actually the tank itself. Proper leak identification is critical before moving on to the big deal of removing the tank only to find it wasn’t worth it! Sounds terribly obvious, doesn’t it, but you’d be surprised. Don’t be fooled by tiny little leaks. In steel and aluminum tanks, a puncture is sometimes just an indication of a much larger problem inside.
Many tank leaks are caused by corrosion, which is the inevitable result of water sitting undisturbed at the bottom for years. Steel tanks suffer greatly from this, and often the puncture leak is the first sign that the paper-thin bottom is about to fall out, along with the contents. Aluminum tanks also have their own problems. Many alloy tanks are used by people and are often not marine grade aluminum alloy. This means that if they are left sitting in seawater, their chances of surviving ultimate corrosion and failure are slim to none. The wrong grade alloy literally melts in sea water! Much damage can be done if aluminum tanks are placed on rubber mats or cushioned with rubber inserts under steel retaining straps. Certain brands of rubber contain chloride and this also destroys aluminum alloys at an alarming rate. Leaving wet rags on top of alloy tanks is also bad news, as the corrosion resulting from the poultice that produces a horrible white sticky substance is also highly corrosive. The same goes for nuts and bolts and any tools left on top of tanks, dissimilar metal corrosion is alive and well in these cases, all wreaking their own particular havoc!
Now that I’ve managed to scare them to death, what do we have? The leak has been identified, assessed and the tank will most likely have to come out in most cases. It’s a bit annoying, but overall it’s a good thing because you can check all the hidden areas behind and clean them at least while the tank is out. A guy I knew did the same thing and found a heavy bag of oil behind the tank. Opening it up he found a .45 automatic pistol and a couple of boxes of bullets…what I want to know is how the hell the previous owner forgot about that. We’ll never know, I guess, maybe he never knew? It was probably from his wife! Once the tank is out, a lot of things will become clear. The next stage is about to evolve and we can truly face the beast.
THE REPAIR ITSELF
Assuming the tank was initially emptied of its contents, we can now decide, can we repair internally or not? Remove the inspection panels and make a decision on whether it is possible to work inside. Being able to see what you are doing is vital. If you have enough space to see and work, great. However, it remains a firm rule for all tanks, large or small, fuel or water, glass or metal, copper or steel, they must all be spotlessly clean, free of grease, free of rust, free of dust, free of slime, free of dust, no particles. , without anything. Did I clear up? Cleanliness is next to mercy in these cases, a good repair begins impeccable. Once clean, it must be thoroughly degreased. In the case of steel, copper, brass, and alloys, it helps if it’s also a shiny metal! If the bottom appears to be leaking, two coats of CSM (Chopped Strand Mat) will usually suffice about 1.5 ounces to ensure the glass rises about ¾ inch above the bottom all the way inside.
If a deeper investigation of the leak at the bottom shows weaker metal and a larger hole (or several), then it’s best to make sure the repair is done from the outside. This can be accomplished by backing the moistened fiberglass mat with a stiff piece of cellophane-covered cardboard, which, in turn, is firmly taped to the bottom of the tank with plenty of tape. This ensures that the glass does not bend, sag, or even fall out under its own weight during curing. Be generous with the size of the patch, the bigger the better. Curing can be made easier by heating with a hair dryer or even adding a little more to the resin/catalyst mix. NO, however, if epoxy resin is used… strict measures only please! Allow a minimum of 12-15 hours, preferably overnight. Please note: Gas tanks should be steam cleaned prior to any repairs.
Remember, in the case of fuel tanks, it is essential that the repair is completely degreased. It is almost certain that the resin will not adhere and the process will have to be repeated one more time. Degreasing can be done with trichlorethylene, carbon tetrachloride, detergent solution, or a proprietary degreaser. Don’t cut this step short… you can’t say you weren’t warned!
Sealed tanks of course need to be repaired from the outside and it may be worth considering completely covering the entire tank with glass, especially if you use a couple of layers of thin fabric and filled resin to do so. You can give the tank a whole new life, especially if you paint it a bright new color afterward. However, be careful that the corroded parts do not come off in the future, which could block the pipes, filters and cause the engine to stop in a very uncomfortable moment. An additional tip in this scenario to ensure there are no loose particles is to pour 2-3 liters of resin/catalyst mixture into the fill tube through a funnel to completely seal the bottom and forever preserve any loose scale or debris. dust after glass. the outside. It’s so cheap to make and well worth the extra effort!
LEAKING SEAMS
A leaky seam may seem like an impossible job, but with patience it’s a doddle. Thoroughly clean all around the seams and degrease. Simply mend around the entire seam overlap at both ends of the tank.
A WORD ABOUT WATER TANKS
When water tanks are repaired with general purpose (polyester) resins, the styrene residue that is present (about 50 parts per million) imparts a “flavor” to the water. It is not harmful as such, but it is quite undesirable and the taste will linger for some time. In boats or caravans, the water is not used as quickly and it can take time to rinse. However, certain resins that are recommended for potable water supplies may be used. Check with your resin supplier for advice. However, always cure water tanks for at least seven days and rinse repeatedly with hot water, which removes much of the styrene taste. You can also steam clean the tank at your local garage for a reasonable fee… well worth it.
TEMPORARY REPAIR
On a boat it is vital to always have something on hand to repair a sudden leak or burst pipe. There are several varieties of two-part epoxy putty and epoxy pipe tape available. Make sure the temporary repair doesn’t end up being permanent though, some of these putties really do work well, even soaked in fuel or water. sure!
With today’s ever increasing costs, new tanks are really expensive, several thousand for large yachts and it’s always satisfying to be able to do a safe and efficient repair for a fraction of the cost of replacing them. It takes a little extra effort, but think of the hundreds of hours of work you’d have to put in to pay hundreds of extra dollars for new ones.
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