Roymech engineering encyclopedia

Flange Dimensions, PN Ratings and Pipe Threads (BS4504 & EN 1092)




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Flange dimensions and PN ratings are used in piping systems to define pressure capability, bolt patterns and connection sizes. Standards such as BS4504 and BS EN 1092-1 specify dimensions for flanges used in engineering and process industries.

This section provides tables for PN16, PN25 and PN40 flanges, along with pipe dimensions and pipe thread data used in mechanical and piping design.

Flange and Pipe Data

The pages below include flange dimensions, pressure ratings, pipe standards and thread specifications used in piping systems and mechanical engineering applications.

Popular Flange Data


BS4504 PN16 Flanges

BS4504 PN16 Flanges are now obsolete, it remains in use for the dimensions of light duty, economy stainless steel flanges in applications where corrosion resistance and hygiene is important.

BS4504 PN16 Flanges

BS4504 PN25 Flanges

BS4504 PN25 Flanges are now obsolete it remains in use for the dimensions of light duty, economy stainless steel flanges in applications where corrosion resistance and hygiene is important.

BS4504 PN25 Flanges

BS4504 PN40 Flanges

BS4504 PN40 Flanges are now obsolete, it remains in use for the dimensions of light duty, economy stainless steel flanges in applications where corrosion resistance and hygiene is important. 

BS4504 PN40 Flanges

BS EN 1092-1 PN16

PN16 Raised face slip-on bossed welding forged flanges to BS EN 1092-1:2018

BS EN 1092-1 PN16

BS EN 1092-1 PN25

PN25 Raised face slip-on bossed welding forged flanges to BS EN 1092-1:2018

BS EN 1092-1 PN25

BS EN 1092-1 PN40

PN40 Raised face slip-on bossed welding forged flanges to BS EN 1092-1:2018

BS EN 1092-1 PN40

BS1600 Pipes

BS1600 Pipes dimensions.

BS 1600 Pipes

BS3600 Pipes

BS3600 Pipes dimensions.

BS3600 Pipes

Pipe Threads

Pipe Threads dimensions.

Pipe Threads

Note: Standard BS 4504 is now superseded by

BS EN 1092-1:2002 Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, PN designated. Steel flanges.

BS EN 1092-2:1997 Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, PN designated. Cast iron flanges.

BS EN 1092-3:2003 Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, PN designated. Copper alloy flanges.

BS EN 1092-4:2002 Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, PN designated. Aluminium alloy flanges.

BS EN 1515-1:2000 Flanges and their joints- Bolting: selection of bolting.

BS EN 1515-2:2000 Classification of bolt material for steel flanges PN designated.

BS 3600:1997 :Specification for dimensions and masses per unit length of welded and seamless steel pipes and tubes for pressure purposes. Is withdrawn and replaced By BS EN 10220:2002..Seamless and welded steel tubes. Dimensions and masses per unit length