Hydraulic Sealing Components

Rotary Seals

'O' Rings

Compression Packings


'O' Rings

The humble 'O' ring is an exceptionally versatile sealing device. Applications ranging from garden hose couplings to critical aerospace duties make it the world's most popular volume produced seal.

We have been making top-quality 'O' rings since this sealing method was introduced in the 1930s.

Today we hold a vast range of stock sizes and materials for same day despatch - and back this with an emergency manufacturing service to supply you any items that we do not have immediately available.

Our range covers:

Standard 'O' rings

Customised 'O' rings
'O' ring back-up rings
'O' ring cord
'O' ring kits
'O' ring lubricants



Many industrial standards - many thousands of sizes

We manufacture and stock 'O' rings in numerous size ranges including:

  • BS 1806 & SAE AS568A (inch sizes)
  • BS 4518 (metric sizes)
  • ISO 3601-1 & DIN 3771-1 sizes
  • JIS B2401 (Japanese sizes)
  • BS 4825 (food industry quality)
  • JW 17000 (special inch sizes)


Materials - natural rubber to exotic engineering plastics

The development, processing and application of fluid seal materials are James Walker specialities.

We supply our 'O' rings in one of the most comprehensive ranges of materials currently available. This includes, in alphabetical order:

Aflas® TFE/P - Resists oils, lubricants and some fuels. Suitable for sour (H2S) gas duties, and with amines or high temperature water/steam. Explosive decompression resistant grades are available.

Buna N - see Nitrile.

Butyl IIR - Very low gas permeability. Suitable for vacuum and high-pressure duties. Not to be used with mineral oils.

Elast-O-Lion® HNBR - Our range of high-performance hydrogenated nitrile compounds with excellent mechanical properties. Explosive decompression grades of 'O' ring are available ex-stock.

Ethylene propylene EPM/EPDM - Excellent resistance to weathering, ozone, hot and cold water and steam. EP 18/H/75 range of 'O' rings available ex-stock. EP62 range supplied for potable water duties.

Fluolion® PTFE - Outstanding resistance to virtually all chemical media. Virgin PTFE and a wide range of filled materials are processed in-house.

Fluorel® - see Fluoroelastomers.

Fluoroelastomers FPM/FKM - Operate efficiently under severe chemical conditions and at higher temperatures. We have developed many grades based on ingredients such as Viton®, Tecnoflon® and Fluorel®. 'O' rings in explosive decompression resistant grade FR 58/90 and general purpose FR10/80 are supplied ex-stock.

Fluorosilicone FVMQ - Recommended for static seals in aerospace fuel systems. Resistant to hydrocarbon oils, petroleum fuels and mineral-based hydraulic fluids.

Hydrogenated nitrile - see Elast-O-Lion®.

Hypalon® CSM - Chlorosulphonated polyethylene has excellent resistant to weathering. Good service with many media on static sealing duties.

Kalrez® FFKM- These perfluoroelastomer compounds offer the ultimate performance for elastomeric materials when considering heat and chemical resistance. All the components we specify and supply are manufactured by DuPont Dow Elastomers.

Natural rubber NR - Compounds based on natural rubber have high strength and high resilience with good abrasion resistance. Suitable for hot and cold water, ammonia, ethylene glycol, dilute acids and alkalis.

Nitrile NBR - We process a wide range of compounds based on various acrylonitrile/butadiene copolymers. PB80 is our most popular stocked grade for 'O' rings. Recommended for mineral oils - particularly hydraulic fluids - water and some solvents.

Polyurethane AU/EU - 'O' rings in this material are often used for drive transmissions where tensile strength and resistance to elongation and wear are needed. It also has excellent resistance to weathering and good resistance to hydrocarbon fuels and mineral oils. Sealing applications are limited by stress relaxation above +50°C.

Silicone VMQ - Good resistance to heat, weathering and compression set at high temperatures, plus excellent electrical properties. Our preferred grade is SIL 80/2. Sealing applications are limited by gas permeability, low tensile strength and low abrasion resistance.

Tecnoflon® - see Fluoroelastomers.

Viton® - see Fluoroelastomers.Neoprene®, Hypalon®, Viton® and Kalrez® are DuPont Dow Elastomers registered trade marks. Tecnoflon® is an Ausimont registered trade mark. Fluorel® is a 3M registered trade mark. Aflas® is an Asahi Glass registered trade mark. Elast-O-Lion® and Fluolion® are James Walker registered trade marks.

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We will swiftly produce any size of non-standard 'O' ring you need by using one of the three following techniques.

Moulding - our main method of 'O' ring manufacture

  • Moulding produces the highest integrity seals
  • Over 10,000 mould tools in our inventory
  • Non-stocked tools rapidly made to specification
  • Press capacity for precision moulding of endless
  • 'O' rings up to 2.3m diameter.



Extruding and mould-joining - for customised economy

  • Non-standard 'O' rings for static duties only
  • Ends of an extruded cord are vulcanised together
  • in a mould to form an endless ring
  • 3mm minimum section diameter
  • 200mm minimum ID of 'O' ring.


Moulding and mould-joining - for top quality giant seals

  • Often used for seals that exceed 2.3m diameter
  • Section diameters to very close tolerances
  • Diameters over 2.3m: two or more smaller rings are precision moulded then cut and mould-joined
  • Diameters under 2.3m: larger ring is precision moulded then cut back and mould-joined.

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We recommend that back-up rings are installed to prevent the extrusion of an 'O' ring seal in its housing groove under certain operating conditions.

Our back-up rings are usually manufactured from Fluolion® PTFE. They should be used:

  • Where fluid pressure exceeds 100bar
  • Where low strength O' rings are installed
  • Where adverse mechanical conditions prevail
  • If the application is double-acting, use two back-up rings - one on either side of the seal in its housing groove
  • But contact James Walker for technical advice if fluid pressure is likely to exceed 420bar.

Fluolion back-up rings are normally supplied as a flat spiral of two turns. This allows the back-up ring to be opened with ease for fitting over a shaft, and ensures the 'O' ring is supported around its entire diameter. Solid back-up rings, of both split and endless types, are also available.



We manufacture and stock a wide range of elastomeric 'O' ring cord. Many customers find this extruded material a useful maintenance expedient for the on-site fabrication of emergency seals.

  • Stocked in popular sections between 1.6mm and 12.7mm diameter
  • Materials: fluorocarbon, nitrile, ethylene propylene, Neoprene, and silicone compounds.

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Seal kits - the maintenance engineer's saviour

Our robustly boxed kits of popular sized metric and imperial (inch) 'O' rings help engineers to store and carry a selection of rings to suit many industrial applications.

Imperial (inch) Kit

  • 382 'O' rings
  • In 30 different sizes
  • Moulded in 70 IRHD nitrile
  • Each different size is individually stored for easy identification and stocktaking.    

Metric Kit

  • 404 'O' rings
  • In 30 different sizes
  • Moulded in 70 IRHD nitrile
  • Each different size is individually stored for easy identification and stocktaking.


Service Kit

  • 14 popular sizes of 'O' ring cord in 2m lengths
  • Extruded in 70 IRHD nitrile
  • Knife, tape measure, slicing aid and adhesive, for forming rings on site



 Identikit - all the seals you need for specific equipment

James Walker Identikits are custom-assembled set of seals and gaskets contained in easy-to-view 'blister' packs. Complete sets of sealing products for assembling or refurbishing a specific piece of equipment

  • Each component is visible and held firmly in place
  • Installation location of each component is clearly
  • identified on a diagram of overall assembly
  • Every kit has a single part number to simplify your ordering, stockholding and parts issuing routines.




We recommend that the following James Walker lubricants be applied lightly to 'O' rings before assembly.

James Walker Molyon Grease - our most popular brand

  • High quality lithium-based grease
  • +125°C maximum operating temperature
  • DO NOT use on seals manufactured from: Natural Rubber NR, Butyl IIR or Ethylene-Propylene EPM/EPDM
  • compounds.

James Walker Silicone Grease - for higher temperatures

  • High quality silicone grease
  • +200°C maximum operating temperature
  • DO NOT use on seals manufactured from: Silicone VMQ compounds.

James Walker Anti-Seize Compound - highest temperatures

  • Top quality mineral-based product
  • For temperatures above +200°C
  • DO NOT use on seals manufactured from: Natural Rubber NR, Butyl IIR or Ethylene-Propylene EPM/EPDM compounds.

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