For certain demanding applications, metallic gaskets are sometimes the preferred choice. While some specialized applications, such as those in the petroleum industry, do require solid metal gaskets, other applications can be serviced with semi-metallic gaskets.
Semi-metallic gaskets consist of a combination of metallic and non-metallic materials. The metal gives the gasket strength, while the non-metallic materials provide the sealing component. Semi-metallic gaskets can be a preferred sealing option where higher temperatures and pressures are application factors to be addressed.
The most widely used form of semi-metallic gaskets are spiral wound gaskets. Usually, a spiral wound gasket has metal wound in a spiral pattern, with the non-metallic filler material (usually a flexible graphite material) wound in the same manner but starting from the opposite side of the gasket. This results in alternating layers of filler material and metal. The presence of the filler material acts as the sealing element, while the metal gives structural support to the gasket. Spiral wound gaskets have proven to be reliable in many applications, and they permit lower clamping forces than do solid metal gaskets
Canada Rubber Group Inc. (CRGI) can supply spiral wound gaskets in a variety of styles to suit the particular flange facing used on the flange being sealed. We offer the following Teadit styles of spiral wound gaskets:
911/911T. This is the simplest style of spiral wound gasket, consisting of a circular winding without centering or inner rings. Style 911 gaskets are mainly used in tongue and groove or male and female flange connections. They are also used in equipment with space and weight limitations.
911M. A spiral wound gasket consisting of a sealing winding with an inner ring. The purpose of the ring is to fill out the space between the flanges, avoiding turbulence in the flow of the fluid, or as a protection against corrosion or erosion. It is also used as a compression limit when the seating stress is greater than 30,000 psi (210 MPa). Gaskets with PTFE filler have a tendency to inward buckle; thus the use of an inner ring is recommended if the gasket is to be installed with a non-confined inside diameter.
913. This gasket is constructed of a circular metal winding with an outer guide ring. The sealing element is made of the specified metal and soft sealing material. Standard pipe size gaskets are made to ASME B16.20 (see also style 913M). These gaskets are used in a very wide variety of applications.
913M. A spiral wound gasket consisting of a standard spiral wound gasket with an inner ring. The purpose of this ring is to fill out the space between the flanges, avoiding turbulence in the flow of the fluid or as protection against corrosion or erosion. It is also used as a compression limit. Gaskets with PTFE filler have a tendency to inward buckle; thus the use of an inner ring is required by ASME B16.20. Inner rings are also required with ASME standard spiral wound gaskets with flexible graphite fillers, unless the purchaser specifies otherwise, and some sizes and pressure classes require inner rings regardless of filler material.
914. These spiral wound gaskets have windings in non-circular forms, such as oval, rectangular and square (with rounded corners), diamonds, oblong or pear shaped. Style 914 gaskets are used in boiler handholes and manholes, equipment, engine head-gaskets and exhaust systems. Inner rings should also be used for many of these applications.
We will be pleased to discuss your spiral wound gasket needs. Emergency service is available for both standard and non-standard gaskets.
To find out more about any of our spiral wound gaskets, please contact our sales department at crg@canadarubbergroup.com.