Pipes and tanks go together like fish and chips. Del and Rodney. Jägermeister and Red Bull. And whilst we have written our fair share of guides for fixing various types of pipe leaks over the years, we have never taken the time to issue guidance about how to patch repair a tank. Until now.
Tanks can develop cracks and holes for all kinds of reasons. Wear and tear and corrosion are two of the most common. Whatever the cause of the problem, the size and fluid of the tank, or its location, it can normally be fixed with a composite patch repair.
What is a composite patch repair?
A composite patch repair is a method similar to fixing a leak with a pipe repair bandage in that both involve resin and a bandage.
The difference is that a pipe repair bandage is already impregnated with a water-activated resin. It arrives ready-to-use. When the bandage becomes wet, the resin begins to cure.
As the bandage is wrapped and smoothed around the pipe, it sets to an impact resistant, rock hard material. This material encompasses the pipe in a protective sleeve, strengthening and reinforcing it.
When it comes to tank repair, you cannot feasibly wrap a pre-prepared composite bandage around even the smallest tank to seal holes and cracks.
A patch repair combats this by taking untreated fibreglass tape and coating it with an epoxy resin. The tape can be cut into strips of the required size, coated with epoxy and then layered over cracks and holes.
It will cure to a rock-hard material in exactly the same way as a pipe repair bandage, but without the need to wrap. Instead, tape can be layered on top of itself to build – or patch – a composite repair.
Making a composite patch repair to a tank
The best type of fibreglass tape for making a composite patch repair are those with an open weave structure. This enables the epoxy resin to saturate the fabric more easily, increasing the effectiveness of the repair.
Surfaces have to undergo a degree of preparation prior to a composite patch repair taking place. Paint, rust and grime should be removed and the area needing attention roughened up by grinding with a coarse wheel or abrasive disk pad.
The brushable epoxy resin will be supplied in two parts. These are mixed at the specified ratio until the epoxy is streak free and ready to be applied.
Strips of fibreglass tape are cut off to the required size to cover the crack in the tank. The tape is then coated in brushable epoxy and layered over the hole in the tank.
The application continues in this way, with strips of saturated tape being layered on top of each other. Once cured, the fibreglass will set to permanently seal the crack.
Advantages of a composite patch repair
A composite patch repair is more versatile than using a standard pipe repair bandage. It allows for multiple areas of the same tank, pipe or structure to be repaired at once.
When applying a pipe repair bandage, the area of repair is rather restricted by the fact it must be wrapped. Cutting strips of fibreglass tape and building repairs means that large tanks suffering from several cracks and holes can be repaired in a more cost-effective manner.
Because a composite repair is being made on-site rather than via a pre-prepared bandage, specialist epoxy resins can also be formulated for use in specific applications.
In an industrial setting for example, it might be desirable to create a composite repair with very high chemical or temperature resistance. An epoxy custom-made can offer greater protection in such scenarios than a standard bandage incorporated with a one-size-fits-all resin.
Reinforcing a composite patch repair
There may be instances where further reinforcement of a composite patch repair to a tank is necessary, such as if the tank is in an aggressive or harsh exterior environment.
This can be done by coating the entire tank with a reinforced brushable epoxy. A pharmaceutical plant in Puerto Rico did this when they needed to repair numerous cracks which appeared through the roof of an outdoors tank made brittle by corrosion.
Once they had made an epoxy composite repair using Sylmasta E190 Brushable Epoxy and fibreglass tape, they coated the entire tank in Ceramic Brushable Green Epoxy Coating.
Ceramic Brushable is reinforced with silicone carbide. It set to provide an ultra-smooth, hard wearing layer which sealed the tank from water ingress and helped protect against further corrosion, cavitation, pitting and erosion.
Other applications where a patch repair can be used
As well as tanks, composite patch repairs can be used in complex pipe repair applications, such as when attempting to seal or reinforce difficult shapes where a bandage cannot be applied effectively.
For significant industrial pipelines many metres in diameter, patch repair provides an easier alternative to attempting to wrap massive structures with bandages.
Any application requiring a more versatile repair method than that offered by a standard pipe repair bandage can benefit from a composite patch repair.