January 1, 2010

Sealing Transformer Oil and SF6 Leaks Quickly and Effectively

James Malcolm

It’s All About Adhesion

All of these cases rely on the correct adhesive selection. Oil is an excellent release agent, preventing the vast majority of glues on the market from achieving effective long-term adhesion to steel.

Improvements in oil- and moisture-tolerant polymers changed our options. Belzona 1831 is able to penetrate through the oil and water and bond to even a mechanically abraded substrate, making repairs like these easy.

Surface preparation can be achieved in a number of ways using hand tools such as grinders. However, the best results have been found when using the MBX Bristleblaster, which will quickly and effectively clean the surface of the metal and produce an excellent and consistent profile for the product to bond to.

All of the repairs discussed were accomplished without draining the oil from the equipment by using cold-curing, 100% solids products that require no heat and do not shrink. Unlike welding, these products will not distort the substrates and will bond to all of the rigid materials found in this equipment. When cured, the polymer becomes an inert plastic, aiding disposal and recycling of the unit at the end of its life.

Material Also Seals Gas Leaks

Sulfur hexafluoride (SF6) leakage is also an environmental hazard and another application where this kind of product can provide an effective solution. SF6 is used as a gaseous dielectric medium for high-voltage electric equipment such as circuit breakers and switchgear, and it can be difficult to detect. Once detected, it is imperative that the leak be sealed very quickly, on site, without waiting for a specialist team. The same technology used for sealing transformer oil leaks can also be used to quickly and effectively seal SF6 leaks, as it will bond very well to steel and porcelain insulators (Figure 7).

7. Stop gas leaks. The same sealant has been successfully used to stop SF6 leaks in switchgear. Courtesy: Belzona Polymerics Ltd.

Repairs like these can be completed in as little as one hour without special tools or equipment, and the repair will last for years in the most challenging of environments.

Since this system was launched in the UK, many electrical transfer equipment operators have implemented its use, and now it is being adopted by national electricity distribution companies in other European countries.

— Contributed by James Malcolm (jmalcolm@belzona.com), business development engineer, Belzona Polymerics Ltd.