Bespoke
Generally gaskets manufactured as a "one off" to suit an irregular shaped sealing face. WR Gaskets can produce bespoke gaskets from a drawing, sample, or even a sketch.
Bolt Load
The compressive force exerted on a gasket by the bolting in a flanged joint. Adequate bolt load is essential for the gasket to deform into the flange surface irregularities and create a reliable seal. Insufficient bolt load is one of the most common causes of gasket leakage. View our stud bolts.
Bore
The bore specifies the inner dimension (ID) of the gasket.
CAF (Compressed Asbestos Fibre)
This gasket material is carcinogenic and hence most industries have started to reduce this material usage, replacing it with NAF alternatives.
Carbon Steel (CS)
Steel in which the main alloy is carbon. Carbon steel is used to manufacture spiral wound gaskets, generally on the outer centering ring.
Class
The class of a gasket specifies its standard sizes and rating, e.g. PN 10, PN 16, Class ASA 150#, and Table "H" etc.
Compression Packing
Packings (gland) are produced to suit pump or valve glands or stuffing boxes. They are manufactured by braiding, often pre-treated textile yarns into a square section. The purpose of packing is to form a seal to minimise leakage of the process media. Compression packings cover a large area of products, with temperatures ranging between -250°C to 650°C. View our compression packing.
Cork
A gasket material manufactured from cork wood. Cork material is typically combined with rubbers to give it greater resistance to chemicals and solvents. Cork is a low compression jointing.
Creep
The gradual deformation of a gasket material under sustained compressive load over time. Excessive creep leads to bolt load relaxation and potential leakage. Materials such as expanded PTFE and compressed fibre are particularly susceptible to creep, while graphite and metallic gaskets exhibit lower creep rates.
EPDM
Ethylene Propylene Diene Monomer. A synthetic rubber used to manufacture gaskets, suitable for use with water (a grade for use with drinking water is also available). EPDM is suitable for use up to 120°C. Good resistance to steam, ozone, weathering, and many dilute acids and alkalis. View our rubber sheeting.
Flange
A protruding rim or collar on a pipe, vessel, or piece of equipment, designed to be bolted to another flange with a gasket between them to form a sealed joint. Common flange standards include BS 4504, ASME B16.5, and DIN EN 1092.
Foam / Sponge
Rubber that has been formed into an air-filled matrix structure. Typically used to manufacture environmental and dust seals for equipment. Closed cell sponge repels moisture, whereas open cell absorbs moisture.
Full Face Gasket (FF)
Full faced gaskets and joints cover the full face of the flange and have bolt holes which allow bolts to be fitted through the flanges and gaskets. Often used on flat faced flanges and common in lower-pressure applications. Order full face gaskets.
Gasket
A part that fits between two pieces of metal, typically for sealing purposes. Gaskets are commonly, although not always, made of flexible and compressible material. They are manufactured from a wide range of materials including rubber, compressed fibre, graphite, PTFE, and metal, selected based on the operating temperature, pressure, and media. View our custom cut gaskets.
Gasket Paper
Otherwise known as cellulose paper or oil paper jointing. A paper impregnated with chemicals to make it resistant to oils, fuels, and solvents. Commonly used in low pressure and low temperature applications as an economical alternative to NAF.
Grade X
This grade of gasket material meets the requirements for British Standard BS7531 Grade X. These materials are generally suitable for use up to a medium pressure grade of 100 bar and to 400°C.
Grade Y
This grade of gasket material meets the requirements for British Standard BS7531 Grade Y. These materials are generally suitable for use up to a pressure grade of 70 bar and to 350°C.
Graphite Filler
A gasket material commonly used with steam applications. Used as filler material in spiral wound gaskets and available as sheet material for cut gaskets.
Inner Bolt Circle (IBC)
Inner Bolt Circle gaskets and joints fit within the inner diameter of the bolts. Also known as raised face joints (RF). Order IBC gaskets.
Inner Diameter (ID)
The inner diameter specifies the inner dimension or bore size of the gasket.
Jointing
A general term for gasket sheet materials, particularly compressed fibre sheets and graphite laminates, from which gaskets can be cut. The term is commonly used in British English to refer to the sheet material rather than the finished gasket. View our jointing materials.
Kammprofile Gasket
A metallic gasket with concentric serrations (grooves) machined into both faces, typically coated with a soft sealing layer of graphite or PTFE. Widely used in heat exchangers and high-integrity flange connections. View our gasket range.
NAF (Non-Asbestos Fibre)
Non-asbestos materials that replace asbestos gasket materials (CAF). The materials typically have a non-asbestos fibre, e.g. Kevlar, glass, or carbon base, bonded with synthetic rubber. Available in a wide range of grades for different temperatures, pressures, and chemical environments. View our jointing materials.
Neoprene
A synthetic rubber used to manufacture gaskets. Neoprene gaskets are commonly used for exposed environment applications, such as those involving sea water, and also has good gas tightness properties. View our rubber sheeting.
Nitrile
A synthetic rubber used to manufacture gaskets. Nitrile gaskets are commonly used for applications involving oils and fuels. View our rubber sheeting.
O-Ring
A loop of rubber or elastomer with an O-shaped cross-section. Measurements required are the inside diameter and cross-sectional diameter of the chord. Also manufactured from PTFE for exceptional chemical resistant properties.
Outer Diameter (OD)
The outer diameter specifies the outer dimension of the gasket.
Pipe Gaskets
Gaskets which fit the standard range of pipes. They are specified by their bore size, thickness, table/class and style, i.e. Full Face (FF) or Ring style (IBC) to suit raised face joints. Browse our pipe gaskets.
Pitch Circle Diameter (PCD)
The circle passing through the centre of the bolt holes. For example, eight holes equally spaced on a 200mm PCD.
Pressure Rating
The pressure the material can seal against.
PTFE
Polytetrafluoroethylene. A plastic used for making gaskets that is extremely chemically inert, resistant to chemicals and corrosives. PTFE also has a low coefficient of friction. Available as virgin PTFE, filled PTFE, and expanded PTFE (ePTFE). Temperature range -200°C to +260°C.
PTFE Envelope
An 'envelope' of PTFE designed to line the bore of a pipe gasket. PTFE is an extremely inert material but comparatively expensive. Having a PTFE bore-liner is a way of gaining the chemical resistance of PTFE without the associated costs. Envelopes can be fitted to rubber or non-asbestos type gaskets.
Ring Type Joint (RTJ)
A metal ring with a cross section which is either oval or octagonal. The most common RTJ joints are manufactured in soft iron or stainless steel. Used in high-pressure oil and gas applications where a metal-to-metal seal is required.
Rubber
An elastic type polymer material that comes in natural and synthetic compositions. Used extensively for gasket manufacturing. View our rubber sheeting.
Rubber Binder
Binds and adheres the fibres together in NAF gasket materials. Most common will be nitrile rubber, due to its oil resistance properties.
Shore Hardness
Shore A (otherwise known as durometer) specifies the hardness of rubber material, e.g. 70 SH.
Silicone
A synthetic rubber used to manufacture gaskets. Silicone can withstand 200°C and is widely used in the food processing industry. View our rubber sheeting.
Spiral Wound Gasket (SWG)
Spiral wound gaskets are made of a metal coil, or winding, with a material filler. They allow for a higher bolt loading of the pipe flanges and can withstand very high pressures. The combination of metallic and soft filler materials provides excellent resilience and recovery. View our spiral wound gaskets.
Stainless Steel (SS)
A steel alloy resistant to corrosion. Generally SS 316L is used on the inner support ring and on the winding material of spiral wound gaskets.
Table / Flange Dimensions
These define gaskets to fit particular flanges. For example, ASME standard type joints have class ASA 150# / ASA 300#, DIN standard type joints have class PN 10 / PN16, and BS Table joints have flange dimensions to Table "H" etc.
Thickness
The thickness of the gasket. It is generally recommended to select the thinnest gasket possible subject to the application. The pressure on the gasket will increase in proportion to its thickness.
Torque
The rotational force applied to a bolt during tightening, measured in Newton-metres (Nm) or foot-pounds (ft-lbs). Correct bolt torque is critical for achieving the right gasket compression without damaging the gasket or flange.
Type R
Spiral part only, without outer centering ring. Commonly used for valve bonnets. See our spiral wound gaskets.
Viton
A synthetic rubber used to manufacture gaskets. Viton can withstand temperatures up to 250°C and is a very inert but expensive rubber. Viton gaskets are typically used in extreme environments, in the presence of acids and corrosives. View our rubber sheeting.
White Food Quality (WFQ)
Most commonly used in Nitrile, Neoprene and Silicone rubbers, suitable to be used in the food industry.