Question: What options do we have for high-performance liquid gaskets these days?
Answer: Many industrial and automotive gaskets are pre-formed by molding them from rubber. However, liquid gaskets have been available for many years.
There are two types of liquid gaskets: “form-in-place” or “cure-in-place.” Pre-formed and liquid gaskets create seals in different ways;―a pre-formed gasket relies on compression of the flanges to make a seal, whereas a liquid gasket is applied between flanges just before assembly and completely fills the space between flanges, then cures to a solid and does not require compression.
The most common types of liquid gaskets are RTV silicones and anaerobics. In general, the flexible silicones are used where some flange movement is expected in an assembly, and anaerobics are used for very rigid assemblies. Silicones were historically said to be unsuitable for many applications because of poor oil resistance, but this weakness has been overcome and they are widely used at both the OEM level and in the automotive aftermarket.
Anaerobics have been widely used by manufacturers of off-road vehicles where relatively low production volumes cannot justify making specialty molds for pre-formed gaskets. A sort of hybrid system has been introduced, which uses an acrylic backbone like in an anaerobic but cures by interaction with atmospheric moisture just like a silicone. Some liquid gasketing compounds are also based on polyester urethanes, which were original developed for the aviation industry. These are frequently used as gasket dressings in addition to some gaskets.
Recent developments in gasketing include the capability to apply a liquid gasket to one flange and then cure it in place to form a part with a gasket already on it. Such cure-in-place gaskets are cured by heat or UV radiation and behave like pre-formed gaskets.
Any views or opinions expressed in this column are those of the author and do not represent those of ASI, its staff, Editorial Advisory Board or BNP Media.