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Materials

Flexseal uses the following materials in the manufacture of its products (click the material name for more information):

Elastomer Materials

The majority of Flexseal couplings are manufactured using a highly versatile EPDM rubber sleeve with stainless steel clamping bands. The sleeve is used to create an air and watertight seal on the pipe surface and the stainless steel clamping bands produce the compressive force that forms the seal. Stainless steel shear bands are used in some of the product range to resist lateral movement across the joint caused by ground settlement.

An elastomer can be broadly defined as a natural or synthetic elastic material. The elastomer compounds used in our coupling sleeves meet the requirements of BS EN 681:1. This is a requirement of the coupling manufacturing standards and ensures that the EPDM rubber compounds used meet specified physical performance criteria and as such the longevity and performance of the products is assured.

EPDM Rubber (Ethylene Propylene Diene Monomer)

Advantages:
• A high performance synthetic rubber.
• Ethylene Propylene Diene Monomer has excellent resistance to ozone, weathering and sunlight.
• Excellent heat resistance and very good flexibility at low temperature.
• EPDM generic temperature range is -50ºC/+150ºC.
• Flexseal states: continuous operation at 80ºC; intermittent at 100ºC.
• Has a good general chemical resistance and can be used above ground.
• Inherently has good resistance to alkalis, acids and oxygenated solvents.
• Superior resistance to water & steam.

Limitations:
• EPDM has poor resistance to oil, gasoline and hydrocarbon solvents.

Remarks:
Due to its unique combination of physical properties, EPDM can be used in an unusually broad range of products. Aside from applications requiring resistance to oil and hydrocarbon solvents, there is scarcely an application in which EPDM is totally unsuitable.  Because of its excellent resistance to ozone, sunlight and severe weather conditions, EPDM is ideal for outdoor service.

SBR Rubber (Styrene Butadiene)

Styrene Butadiene (SBR) is occasionally used by Flexseal as an alternative to EPDM for products with an underground use only.

Advantages:
• Styrene Butadiene has excellent impact strength: very good resilience, tensile strength, abrasion resistance and flexibility at low temperature.
• SBR has a generic temperature range of -45ºC/+100ºC.

Limitations:
• Styrene Butadiene is not as suitable for above ground applications and has a lower heat resistance than EPDM.
• Poor resistance to ozone and sunlight: very little resistance to mineral oil, oil, gasoline and hydrocarbon solvents.

Remarks:
SBR is much like natural rubber in most of its properties. The physical properties meet the requirements of EN681:1 and therefore this elastomer is a good alternative to EPDM but cannot be used above ground. Also the material does not have the same resistance to high temperature as EPDM.

NBR Rubber (Nitrile or Acrylonitrile Butadiene)

Nitrile or Acrylonitrile Butadiene (NBR) can be offered as an alternative material for instances when the drainage effluent is contaminated by hydrocarbons.

Advantages:
• Very good resistance to oils, petrol, diesel and greases.
• NBR generic temperature range is -20ºC/+120ºC.
• Good resistance to alkalis and acids.

Limitations:
• Poor resistance to ozone and sunlight.

Remarks:
The physical properties of the compound meet the requirements of EN 681:1 NBR is used in specific applications for effluent contaminated with hydrocarbons, oils, fats and greases.  It should be noted that the nitrile compound is classed as medium grade and is therefore only suitable for drainage applications.

Click Here for Nitrile Couplings Technical DataSheet

Comparison of elastomer materials

Environmental Resistance Properties

 

EPDM

SBR

NBR

Oxidation Resistance

G-E

F-G

F-G

Ozone Resistance

E

P

P

Weathering Resistance

E

F

F-G

Sunlight Resistance

E

F

P-F

Water Resistance

E

G-E

G-E

Flame Resistance

P

P

P

Heat Resistance

G-E

F-G

G

Key:  E = Excellent   G = Good   F = Fair   P = Poor

 

Chemical Resistance Properties

 

EPDM

SBR

NBR

Oil and Petrol

P

P

G-E

Animal and Vegetable Oils

G

F

G-E

Alcohols

F-G

G

F-G

Alkalis

G-E

F

G-E

Acids

G

F-G

G

Key:  E = Excellent   G = Good   F = Fair   P = Poor

 

Plastics

Plastic, in the form of flexible PVC, is the base material for the Fernco PVC Coupling range, in place of the elastomeric sleeve used in Flexseal flexible couplings.  Plastics also feature in other product ranges such as saddles, drainage channels and air admittance valves.

Flexible PVC

Flexible PVC (Polyvinylchloride) is a durable thermoplastic material. Plasticizers are used with PVC plastic to produce a flexible material. The material exhibits many of the chemical resistance characteristics of the plastic but is flexible and durable enough to be used as a sealing material.

Advantages:

  • Strong, resilient and unaffected by soil conditions.
  • Resistant to a wide range of chemicals.
  • Resistant to the environment normally associated with sewers and drains.
  • Flexible PVC has an operating temperature range of -34°C/+60°C.
  • We recommend: continuous operation at 40°C; intermittent at 60°C.
  • Couplings manufactured from PVC can be used above ground.

Limitations:

  • Flexible PVC has poor resistance to fats, oil, and greases and hydrocarbon solvents.

Remarks:

Flexible PVC offers a more economic alternative to other elastomers.  Flexible PVC is not included within the UK manufacturing standard.

Rigid PVC

Rigid Polyvinylchloride (PVC) is a widely used durable thermoplastic material. Without the addition of plasticizers it is a hard and rigid material.

Advantages:

Resistant to a wide range of chemicals. 

Limitations:

PVC has limited or poor resistance to aldehydes, halogenated hydrocarbons and ketones.

Remarks:

Can be machined, bent, welded and glued making it very useful for plastic fabrications.  Rigid PVC has an operating temperature range of -25°C/+70°C.  The Fernco range of Air sure air admittance valves is predominently manufactured from rigid PVC. 

ABS

Acrylonitrile Butadiene Styrene (ABS) is the polymerization of Acrylonitrile, Butadiene and Styrene monomers. It combines these three different monomers to form a single material that draws from the properties of all three constituents.

Advantages:

  • Outstanding impact strength.
  • High mechanical strength.
  • Excellent general chemical resistance.

Limitations:

  • Limited chemical resistance to weak acids.
  • Poor chemical resistance to strong acids and strong solvents.

Remarks:

Used by Flexseal to manufacture the plastic components of the FA, PA and UA saddle products. Maximum operating temperature of 80° C. Minimum operating temperature of -20°C.

Polypropylene Copolymer

Polypropylene (PP) is a widely used chemically resistant and durable plastic.

Advantages:

  • Excellent general chemical resistance.
  • Tough.
  • High impact strength.
  • Resistant to fatigue when flexed under load. 

Limitations:

  • Limited chemical resistance to Halogenated Hydrocarbons and Oxidising Agents.

Remarks:

Used by Flexseal in the manufacture of channel drain products.

Nylon

Nylon (or Polyamide) is an extremely useful engineered thermoplastic. 

Advantages:

  • Good to excellent chemical resistance to oils and solvents.
  • Easily machined.
  • Tough, strong and impact resistant.
  • Very low coefficient of friction.
  • Abrasion resistant.

Limitations:

  • Poor or little chemical resistance to acids and alkalis

Remarks:

Flexseal saddle components contain nylon as a 30% glass filled variant for toughness and strength.

Stainless steel

Stainless steel is used for the manufacture of clamping bands, shear rings and other components within Flexseal products.

The term stainless steel is applied to a range of iron based alloys which rely on their chromium content for resistance to corrosion. The stainless steels used with our Flexible Couplings are classed as Austenitic Stainless Steels. The term Austenitic steel refers to the microstructure of the steel caused by the alloying elements. The steels used by Flexseal have 17%-18% Chromium content and 8% -11% Nickel content and are in full compliance with the manufacturing standards of BS EN 295:4 and WIS4-41-01. Such steels offer a good combination of corrosion resistance, formability and weldability.

Product is normally supplied with Grade 1.4301 (304) stainless steel. Grade 1.4401 (316) can be fitted where a higher resistance to corrosive elements is required.  The stainless steel used in the manufacture of end caps is a high corrosion resistant marine grade 300 series austenitic stainless steel to BS 970 Part 1: 1983 or BS 1449 Part 2: 1983 as applicable.