What are gaskets and o-rings and why are they so important? In general, gaskets are a type of sealing material between two surfaces used to prevent air or liquid from escaping between those surfaces. Gaskets can come in any shape but the ones most commonly used on railroad tank cars are flat, circular or square shaped gaskets which connect two flat surfaces that are normally bolted on to eachother, such as a valve onto a flange.
O-rings are specialized types of gaskets, also known as a toric joint — in reference to its torus shape — with a circular-looped design that’s used to seal two working surfaces. The valve stems in pressure relief devices (PRD) such as safety valves, for example, often use O-rings to prevent vapors from escaping until the internal tank pressure of the railcar exceeds the pressure setting of the PRD. The O-ring creates an air-tight and liquid-tight mating surface between the valve stem and the retainer. Without this small and otherwise simple component, air or commodity may leak into the valve, and unintentionally release vapors or liquids into the atmosphere, also known as a non-accidental release (NAR).
Non-accidental releases are a major focus of the Federal Railroad Administration (FRA) and the Class I railroads. Steep fines can be levied against shippers for mishandling ladings transported on railroad tank cars. It is imperative that anyone who uses a tank car understands and ensures that the commodity they intend to carry is compatible with the gaskets and o-rings on the railcar AND to complete proper pre-loading and post-loading inspections of the railcars for leaks. Ideally, a written chain of custody showing what gaskets and o-rings are on the car and their date of installation will go a long way in preventing NAR’s and safely carrying your cargoes in railroad cars.
As part of our efforts to maintain the safest railcars, we have partnered with VSP as a participant in their RideTight® program, where we offer our customers VSP’s deep industry knowledge and engineering of gasket and chemical compatibility.