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In industrial usage, the term RF gasket usually refers to the annular flat gasket designed for raised face flanges. Unlike an FF gasket, it has no bolt holes and sits inside the bolt circle of the flange.
In current European standards, this geometry is identified as a type IBC (Inside Bolt Circle) gasket. This page focuses on its dimensional identification: the relationship between the old DIN 2690 and the current EN 1514-1, and the data needed to define it. For materials, applications and manufacture, see our flange gaskets page.
RF stands for Raised Face and describes the raised sealing face of the flange. In industrial practice, the term "RF gasket" is often used to refer to the annular gasket that seals on that area.
In EN 1514-1, however, the dimensional designation of this gasket is Type IBC (Inside Bolt Circle): a flat gasket without bolt holes whose outside diameter lies inside the bolt circle. It is defined by three dimensions:
The number of bolts, the bolt hole diameter and the PCD are not part of the gasket, although they help to identify the flange when its standard is not known.
The DN (nominal diameter) identifies the size of the connection and the PN (nominal pressure) the pressure rating of the flange. Specifying only the DN – for example, DN100 – may not be enough: the outside diameter of the gasket can vary depending on the PN and the applicable dimensional series.
As a minimum, you should have:
DN + PN + dimensional reference (DIN 2690 or EN 1514-1 type IBC)
For decades, DIN 2690 was a common reference for flat gaskets intended for flanges with flat sealing faces. For this reason, it still frequently appears on drawings, in catalogues, maintenance records and technical documentation for existing installations.
DIN 2690:1966-05 has been withdrawn. DIN states that it was replaced by DIN EN 1514-1, initially in its 1997 edition, and the current European reference for non-metallic flat gaskets for PN flanges is EN 1514-1:2024.
This does not mean it should automatically be assumed that all historical DIN 2690 dimensions and current EN 1514-1 type IBC dimensions are identical. When replacing an existing gasket, it is advisable to check the DN/PN combination and the actual dimensions before manufacturing or supplying the part.
Need an RF gasket but unsure of the dimensions?
Send us the DN, the PN or a drawing and we will tell you which gasket you need.
EN 1514-1 sets out dimensions for non-metallic flat gaskets, with or without inserts, intended for flanges designated by PN. Its current edition, EN 1514-1:2024, covers, among others, types FF (Full Face) and IBC (Inside Bolt Circle).
For a type IBC gasket, the standard relates the DN and PN of the installation to the inside and outside diameters of the gasket, with applications up to PN63 and sizes up to DN4000, according to its tables and conditions.
If the old gasket or the flange is available but the standard is not, the three gasket dimensions are sufficient: inside diameter, outside diameter and thickness. With the DN, the PN or the flange reference, it is possible to check whether the geometry corresponds to DIN 2690, EN 1514-1 type IBC or another dimensional series.
The bolt pattern can help identify the flange, but it should not be confused with the dimensions of the RF gasket, which has no bolt holes.
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An RF or IBC gasket is annular, has no bolt holes and sits inside the bolt circle: it is defined by its inside diameter, outside diameter and thickness. An FF (Full Face) gasket extends to the outer edge of the flange and includes the bolt holes, so it also requires the number and diameter of the bolt holes and the PCD.
The dimensional references for the two formats must not be used interchangeably. For full face gaskets, see our FF gasket for flat face flanges page.
Flange DN.
PN.
Gasket type: annular / IBC.
Standard, if known.
Required material.
Thickness.
Quantity.If the standard has not been identified, you can provide a drawing or the main gasket dimensions: inside diameter, outside diameter and thickness. To choose the material according to the fluid, pressure or temperature, see our flange gaskets page.
Materials, applications and manufacture of DIN/EN and ASME/ANSI flange gaskets.
Full face gasket with bolt holes: dimensions, EN 1514-1 and how to identify it.
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