Flexible Repair Couplings Product Specification and Performance

Flexible Repair Couplings

British Standard (BS En295) Band-Seal Flexible Repair Couplings and Bushes up to 1000mm diameter comply with the requirements of BS EN295-4 “Vitrified clay pipes and fittings and pipe joints for drainage and sewers – Requirements for special fittings, adaptors and compatible accessories”

WIS 4-41-01 Assessed under the British Standard Certification Scheme, Standard Couplings and Bushes from 100mm to 600mm internal diameter, comply with the requirements of Water Industry Specification WIS 4-41-01 ‘Specification for flexible couplings for gravity sewerage and drainage pipes’. Licence Number 33388.

Danish Standard VA Approval Number: VA2.23/19354

German Standard MPA Approval Number 220000307-01

Approved Quality System BS EN ISO 9001 (BS5750) Band-Seal Flexible Repair Couplings are manufactured under an Approved Quality System which complies with BS EN ISO 9001 (BS5750) and certified by Registered Firm of Assessed Capability Certificate No FM1420

Other international approvals exist – please contact our sales office for details.


Elastomers The elastomeric components of the couplings and bushes are made of one or two types of synthetic rubber, either Ethylene Propylene Diene Monomer (EPDM) or Styrene Butadiene Rubber (SBR). These elastomers offer excellent resistance to normal drainage and sewerage effluents as well as providing excellent long term performance and hence are commonly used to joint pipes. For situations where effluents contain hydrocarbons, fats, greases etc then components are available made in nitrile rubber. Both EPDM and SBR conform to the requirements of BS EN 681-1:1996 “Specifications for elastomeric joint rings for pipework and pipelines – drainage” as well as to ISO 4633:1986.

Stainless Steel Couplings are available in two grades of austenitic stainless steel to suit either normal ground conditions or conditions when additional corrosion resistance is required such as coastal environments with high levels of chlorides in the soil or groundwater. For normal conditions Naylor’s couplings incorporate components manufactured from grade 1.4301 (304) austenitic stainless steel to BS EN 10088-2:1995. This grade meets the requirements of both BS EN 295-4 and WIS 4-41-01 in that it contains a minimum of 17% chromium and 8% nickel. For conditions requiring higher levels of corrosion resistance then components manufactured from grade 1-4401 (316) austenitic stainless steel to BS EN 10088-2:1995 are available to special order. This grade contains 2% molybdenum and is especially suited to marine environments.

Durability when used within the conditions and recommendations detailed in this brochure, for normal underground drainage, the couplings are expected to have a life expectancy equivalent to that of the pipeline.

External Protection external protection is seldom required except where couplings are used in poorly drained coarse sand/gravel or in made up contaminated ground such as colliery spoil and in all cases where the ground or groundwater contains chlorides at levels exceeding 1000ppm. In these situations application of a suitable protective wrapping tape such as “Densotape” will give adequate protection. Alternatively components made from grade 1.4401 (316) stainless steel may be used.

Hydrostatic Pressure when correctly installed Naylor’s range of couplings and bushes will withstand the following hydrostatic test pressures:

  • Standard Couplings and Bushes up to 620mm diameter  = 0.6 bar
  • Large Couplings and Bushes up to 1000mm diameter = 0.6 bar
  • Large Couplings and Bushes over 1000mm diameter = 0.6 bar
  • Adaptor Couplings 0.6 bar Pipe Couplings 0.6 bar Plumbing Couplings = 0.6 bar

Site Testing when correctly installed, all Band-Seal Couplings will withstand the air and water pressure tests specified in BS EN1610:1998 “Construction and testing of drains and sewers”; Water Services Association “Sewers for Adoption”; “Civil engineering specification for the Water Industry” and Building Regulations “Approved Document H”.

Clamping Bands two types of worm drive end clamps are used depending upon the coupling size and type. All clamps have perforated bands which are self cleaning should the band become coated in mud or sand.

Heavy duty “Hi-Torque” worm drive clamps are used on all Standard and Large Couplings over 200mm diameter. For smaller diameter Standard Couplings and Adaptor, Pipe and Plumbing Couplings medium duty worm drive clamps are used.

Recommended Tightening Torque

  • Standard Couplings up to 300mm diameter (NSC290) = 6 Nm
  • Standard and Large Couplings over 300mm diameter = 13 Nm
  • Adaptor Couplings 6 Nm Pipe Couplings 6 Nm Plumbing Couplings = 6 Nm