Glossary of Sealing Terms
Original article date: March 1998
The European Sealing Association says that with the advent of asbestos-free sealing materials engineers need guidance about the new approaches required. Consequently it has published a technical glossary relating to flange and gasket sealing terminology aimed at end users OEMs and contractors.
The publication contains descriptions of all the common terms used in sealing and includes layouts for typical flange and gasket systems of which there are many in common use described below. Units of common usage in flange gasket terminology are listed with conversion factors. Relevant standards are listed together with the details of the organisations which issue them. Common abbreviations complete the lineup.
Flat face flanges contain a full face gasket. This is a non-confined gasket with both flange contact surfaces flat. This type of flange is normally used where the flange material is relatively fragile.
In the raised face flange flange contact surfaces are raised although the gasket is non-confined. Normally the gasket covers up to the inside of the bolts. This type of flange allows assembly and removal of the gasket without having to separate the complete flange system thereby making maintenance work easier. It is used commonly in pipework systems.
The tongue and groove flange has a totally confined gasket. The groove depth is equal to or greater than the tongue height. Normally the gasket has the same width as the tongue. In this design it is necessary to separate the flanges completely to change the gasket. This flange system exerts high seating pressure on the gasket and is not usually recommended for non-metallic gasket types.
The spigot flange also known as the male and female flange contains a semi-confined gasket. This can appear in a wide variety of forms. The depth of the female flange is equal to or less than the height of the male in order to avoid the possibility of direct contact between the flanges when the gasket is compressed. The flange system must be separated in order to change the gasket.
The flat face and groove flange system has a totally confined gasket. The external face of one of the flanges is plain and the other has a groove where the gasket is assembled. They are used in applications where the distance between the flanges must be precise. When the gasket is seated the flanges are usually in contract with each other. Only resilient gaskets should be used in this system.
The ring joint flange is also called an API ring. Both flanges have channels to accept the gasket which is normally made of solid metal.
- European Sealing Association
- 01524 844222
March 1998