When it comes to sealing raised or flat face flanges, two types of gaskets can be used: ring and full-face gaskets. Each type is best suited for specific flange designs, so knowing the difference is important for choosing the type that will best service your application.
First, a word about flange faces. The ANSI/ASME B16.5 (Pipe Flanges and Flange Fittings) and B16.47 (Large Diameter Steel Flanges) standards define various types of flange faces. These include raised face and flat face flange types. Raised face flanges are the most prevalent type found in industrial process applications. Raised face flanges are so-called because the gasket surface is placed upon a raised step which elevates the gasket above the bolting circle of the flange. Raised face flanges allow for the use of a wide variety of gasket designs, including flat ring, spiral wound, and those with double jackets.
Flat face flanges, in contrast, have no raised step and the gasket surface rests completely on the bolting surface of the flange. Full-face gaskets are generally required for flat face flanges.
Ring gaskets have no bolt holes. These gaskets are positioned inside the flange bolts and around the pipe bore. Ring gaskets are typically used on raised face flanges. When used on a raised face flange, the ring gasket is positioned on top of the raised surface of the flange. An advantage of ring gaskets is that they can be installed without having to fully disassemble the joint.
Ring gaskets use less material and, because they lack bolt holes, require less cutting in their production. When ordering ring gaskets, suppliers require three measurements: the ID (Inside Diameter), which matches the pipe bore; the OD (Outside Diameter), which matches the outside diameter of the raised flange face; and the gasket thickness. The desired pressure tolerance of the gasket should also be specified.
A full-face gasket covers the entire face of the flange. Full-face gaskets are typically used on flat face flanges. Full-face gaskets are cut with bolt holes which allow the insertion of the flange bolts through the gasket. When installing full-face gaskets, the joint must be completely disassembled. When ordering full-face gaskets, the ID and OD must be specified together with the bolt circle diameter and the number and spacing of the bolt holes. Gasket thickness and the desired pressure tolerance of the gasket should also be specified.
CRG supplies a wide variety of gasket designs and types, including ring and full-face gaskets. All CRG gaskets are precision cut in our ISO 9001-certified facility from the highest quality materials using the latest CNC production technology.
CRG carries an extensive array of gasket materials, meaning that we can produce ring and full-face gaskets that will service any application. We offer industry-leading order turnaround and emergency service is available upon request. CRG is equally comfortable handling short-run orders or orders involving thousands of parts, and our experienced sales team is always available to provide guidance on material selection. To find out more about ring and full-face gaskets available from CRG, please contact our sales team at email@example.com.
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