MEL COMPOSITES
EXTENDS THE LIFE OF EXISTING METALLIC UNDERGROUND TANKS
WITH INNOVATIVE COMPOSITE REPAIR TECHNIQUES
MEL Composites is a highly experienced raw materials supplier that specializes in vacuum infusion techniques. We spoke with Eduardo Galofre, CEO, about a novel composite repair methodology using a kit-based vacuum infused solution for in-situ fuel tank repair that brings existing steel tanks in line with EU regulations and extends their lifespan with active leak monitoring.
Q – Can you give us a short summary of the typical problems customers reported with their underground fuel storage tanks?
Historically, most underground fuel storage tanks are single-wall steel plate tanks. Surface corrosion on both inner and outer faces leads to through wall defects which cause leaks which can see tanks spilling product and contaminating the soil and ground water below. There is a European standard for underground tanks that requires them to be double-walled but, despite this regulation, many tanks have not been replaced or fitted with a liner. Working in partnership with an engineering bureau, MEL Composites developed a process for transforming single-walled fuel tanks into double-walled tanks, with an interstitial chamber between the walls to allow detection of fuel leaks, using a unique resin infusion process.
Q – Can you describe how composites offered the best repair solution?
Following an inspection that identifies any leaks and weak points, a composite repair solution offers a huge advantage in that it can be applied in-situ, without removing the underground tank. A well-engineered composite solution can be modular (so it fits through the small access hatches) and can be used to create a highly consistent laminate that seals all leaks and restores integrity. It’s also possible to avoid “hot work” and grinding or welding of the steel that might also risk an explosion.
Q – How does your composite repair technique differ from traditional tank repair methodology?
Some work has been done by others with wet laminated systems being applied in poor badly ventilated confined space inside tanks. These techniques have produced low quality laminates and have even led to accidents that endangered the technicians. The MEL process involves the supply of a kit of fully prepared materials, in a format that allows easy access to the inside of the tank and application by unskilled personnel. With these materials, and using a resin infusion process, a new composite tank is made inside the existing one, leaving an interstitial air chamber between them for the placement of a leak detection system. The materials, including fibres, cores and vacuum bags, are supplied cut and tailored for direct installation without having to be processed. The MEL technique culminates with the resin infusion that fully impregnates the fibres and guarantees the quality of the new tank skin; all without exposing the operator to any resin fumes or contamination.
Q – What sort of lifespan does the new composite tank deliver?
Customer requirements vary but we typically engineer the new composite tank liner to deliver the same lifespan as the initial single-wall tank. A key difference with the MEL process, versus a wet laminated tank lining, is the controlled air space we leave between metallic and composite skins. This lets us add an important interstitial sensor, where a leak detection system (pressure or vacuum based) can be installed, offering customers a real-time view of the tank performance, and alerting them to any dangerous leaks.
Q – How does MEL ensure top quality performance from its tank repair kits?
Firstly, our materials and consumables need to be up to the job. For tank repairs we use the same fiberglass reinforcements, resins and consumables that we have tested thoroughly in-house in our own technical lab. This helps us plan how a tank skin will infuse, how the resin will flow and where to add resin inlets. Secondly, we go out to the customer site and we train the operators who will use our kits. We supervise the initial works, but the aim is to pass on the infusion set up and processing skills so that maintenance companies can apply our techniques and ensure a great result on every tank.
Q – Have you been asked to repair other types of structures with composites?
At MEL we do far more than supply materials, most of our customers come to us with a technical challenge and we create a composite solution that works for them. As well as repairing tanks, we have also worked a lot with the wind energy sector assessing blades and helping owners decide if a repair was required. The MEL team was able to take sections of blades, evaluate them in a mechanical testing lab and confirm that a repair was necessary. In many sectors, composites are reaching the end of their planned lifetime and MEL Composites can use its expertise, backed up by NDT analysis or mechanical testing, to re-life these structures or decide on the most economic repair strategy.
