Bolt Sets & Gaskets

Flange Bolt Sets

Bolt sets are supplied in bagged sets containing the appropriate number of bolts, nuts and washers for each flanged joint. A standard set is used to bolt one ductile iron flange to another, whereas extra length bolts are required when connecting a PE stub flange to a ductile iron flange.

Bolt Types

The standard finish to bolt sets is galvanised steel to BS 4 190. A number of finishing options are available depending upon the specification requirement and site conditions.

  • Rilsan coated
  • Stainless steel
  • Sheridised
  • Zinc plated


Flanged joints are both rigid and self-anchoring. Used in above ground situations such as Pumping Stations, Treatment Works, and Industrial Pipelines. Also used in below ground when connecting fittings such as Valves and Hydrants.

The seal between flanged ends is achieved by axial compression of a flat gasket between the flanges, which is tightened with bolt sets, as shown above.

Flange Specifications

The standard flange drilling is normally PN16, on pipes and fittings for working pressures up to and including 16 Bar. Other drilling configurations (PN10, PN25, PN40) require the corresponding number and size of bolts in a set for the specified drilling arrangement.

Bolt sets (Extra Long) for PN16 flanges - DI x PE Joint

Flange Diameter Bolts in Set Bolt Size (mm) Code
50mm 4 M16x65 0820BS50GALV
80mm 8 M16x65 0820BS80GALV
100mm 8 M16x65 0820BS100GALV
150mm 8 M20x70 0820BS150GALV
200mm 12 M20x70 0820BS200GALV
250mm 12 M24x90 0820BS250GALV
300mm 12 M24x90 0820BS300GALV
350mm 16 M24x90 0820BS350GALV
400mm 16 M27x100 0820BS400GALV
450mm 20 M27x100 0820BS450GALV
500mm 20 M30x110 0820BS500GALV
600mm 20 M33x120 0820BS600GALV

Bolt sets (Extra Long) for PN16 flanges - DI x PE Joint

Flange Diameter Bolts in Set Bolt Size (mm) Code
80mm 8 M16x80 082080BSDIPEG
100m 8 M16x80 0820100BSDIPEG
150mm 8 M20x90 0820150BSDIPEG
200mm 12 M20x90 0820200BSDIPEG
250mm 12 M24x100 0820300BSDIPEG

Flange Bolt Set Installation

Bolts should be tightened in the correct sequence and to the appropriate torque. The sequence is determined by the number of bolts in the flange set, however it generally follows a 1,3,2,4 pattern. Torque is determined by the pipe bore and the Bar rating desired (refer to fitting manufacture’s tables).

  • Check that gasket is correct diameter and matches flange drillings
  • Clean flange faces & position gasket
  • Check size & number of bolts (only use rust free undamaged bolts)
  • Lubricate bolt threads with automotive grease
  • Tighten bolts in correct sequence
  • Gasket normally suffers some relaxation
  • Check and re-tighten bolts, if necessary ‘before’ pressure testing

Flange Gaskets

Flange gaskets are available in several formats and are manufactured from a wide range of materials. The most common combination is the full face type made of EPDM, used for jointing ductile iron flanges together (two lug or IBC Ring types are also available). The standard thickness is 3mm, however 4mm and 6mm are also available on request.

Features & Benefits - EPDM Gasket

  • WRAS approved for potable water usage
  • Good resistance to heat, weathering, ozone effects, ketones and esters
  • Not suitable for contact with petroleum liquids, oils, solvents or fats
  • Temperature range between -40°C and +120°C

Applications - EPDM Gasket

Full face gaskets are used between two ductile iron flanges, the gasket covers the full face of the flanges and so is holed to suit the bolt positions.

EPDM Full Face Flange Gaskets

Flange Diameter Code
50mm 0820G50FFE
80mm 0820G80FFE
100mm 0820G100FFE
150mm 0820G150FFE
200mm 0820G200FFE
250mm 0820G250FFE
300mm 0820G300FFE
350mm 0820G350FFE
400mm 0820G400FFE
450mm 0820G450FFE
500mm 0820G500FFE
600mm 0820G600FFE