Sealing the deal: preventing fluid leakages in industrial components

Loctite 518 Sealant enables sealing between two metal surfaces to replace traditional solid gaskets.

Conventional solid-gaskets present limitations in the prevention of fluid leakage between metal flange surfaces. Henkel’s Loctite 518 pen provides a liquid seal that can help manufacturers cut costs and avoid damaging leaks.

Preventing the leakage of fluids is critical in industrial processes and in the operation of machinery where liquids or gases are used. Fluids can often be toxic and hazardous and pose great financial and environmental risks if not handled correctly.

Valves, pumps and flanges frequently figure as components that hold or transmit fluids into plants. Chemical emissions from plants are projected to reach 37 megatonnes by 2020, according to the federal government’s 2016 report on emissions projections. This can potentially be mitigated by preventing the leakage of fluids from industrial equipment.

The flanged joint is one of the basic seals used to keep process fluids (gas, liquid and vapour) where they belong. They accomplish this by forming an impervious barrier against fluid transfer through the mating surfaces.

Traditionally, sealing two metal flanges to prevent leakages has generally been carried out using pre-cut solid gaskets, often made of rubber, metal, cork or even paper. These gaskets have been positioned between two flanges held together by fasteners. It is the contact pressure between the gasket material and the flanges that produce the seal.

The gasket must also be resistant to the fluid that is moving through the flange and be able to withstand the application temperature, pressure, and any micro-movements caused by vibration and thermal cycling.

The shape of solid gaskets mean that each gasket has a fixed flange shape that it can be used on and a fluid resistance dependent on what the gasket material it is made of. This means on an operational level, a manufacturer using solid gaskets will have to keep an inventory of different gasket types and shapes.

Conventional compression gaskets must deform to fill the irregular voids found on the surface of any metal flange. Flange surfaces may seem entirely smooth from the perspective of the naked eye. However, a view of these surfaces from the microscopic level reveals a jagged terrain punctuated by gaps. Conventional compression gaskets can, over time, lose their ability to maintain the required deformation to seal. This gasket relaxation and creep results in a gasket that can no longer provide an effective seal and becomes prone to leakage.

Manufacturers can mitigate these issues by using a liquid gasket. This means that it is always available, even for old or obsolete equipment.

The new member of Henkel’s Loctite gasketing solution range is the Loctite 518 Sealant Pen. Loctite 518 is anaerobic flange sealant, which means that it cures in the absence of air and with metal to metal contact. It is designed to create a form-in- place (FIP) gasket between metal flanges that are bolted together. This enables sealing between two metal surfaces as if there were no gasket present, with the liquid sealant filling the microscopic voids existing between the mating surfaces. The Loctite 518 pen can adapt to flange surface irregularities and gaps of up to 0.125mm.

While solid-cut gaskets frequently leak and tear, and are often unable to fill all surface imperfections, the Loctite liquid sealant can provide consistent surface coverage and fill all the gaps. While the surface finish of materials – including roughness, flaws and imperfections – is incredibly important for conventional solid gaskets, it has no impact on the effectiveness of the Loctite 518 liquid sealant. This is due to the product’s fluidity in the flange assembly process, which enables scratched surfaces to be sealed without the need to rework the damaged surface.

Flanges frequently encounter small micromovements due to vibration, changes in pressure and temperature, shocks and impacts. Distributing stress evenly, the Loctite 518 pen delivers a seal that provides a reliable and long- lasting seal that doesn’t tear or decay.

The liquid sealant allows metal- to-metal ensuring bolt tension throughout the life of the assembly and eliminating the need for retorquing. Further, the Loctite 518 pen can be applied to both horizontal and vertical flange surfaces. Unlike solid gaskets, Loctite 518 pen does not require any additional help to maintain its position on vertical flange surfaces.

Importantly, the Loctite 518 Sealant Pen helps manufacturers cut costs. Firstly, it reduces inventory costs, as there is no longer any need for a large inventory of solid-cut gaskets. It also helps on those older machines where the gaskets are hard to get or no even longer available. Secondly, it also reduces process costs by minimising any waste or excess on application by using a convenient roller.