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Chemical Couplings

Chemical Coupling New Label webThe Flexseal range of Chemical Couplings, supplied by Fernco, provide a watertight drain and sewer pipe connection or repair.

Flexseal Chemical Couplings provide a flexible and watertight connection on underground drainage systems that require a high resistance to a range of chemical substances.

Manufactured to meet specific site requirements, Flexseal Chemical Couplings are able to withstand the widest possible range of chemicals, due to the shear band and clamping bands encasing a high performance elastomeric sleeve with a chemically resistant one-piece Fluorpolymer (FEP) liner and expanded PTFE seals. Chemical couplings that have a diameter of 400-1000mm are subject to availability.

Chemical Coupling Installation

Chemical Resistance

The FEP liner and PTFE seals are chemically inert and solvent resistant to most chemicals with the exception of molten alkali metals, fluorine at elevated temperatures and other complex halogenated compounds, for example, chlorine trifluoride at elevated temperatures and pressures.

In situations of extreme temperatures, 80% sodium hydroxide, metal hydrides, aluminium chloride, ammonia and certain amonios (R-NH2) may attack the film in a manner similar to molten alkali metals.

Although special testing may be required when such extreme reducing or oxidizing conditions are evident, the FEP liner and PTFE seals exhibit a very broad range of chemical and thermal serviceability. Final selection should be based on functional evaluations or experience under actual end use conditions.

Further information is available from Fernco, or take a look at our chemical coupling video to see how they should be installed:


  • Meet specific site and contractor requirements
  • Watertight joints on chemical drainage systems
  • Withstand broad range of chemical substances


  • Used on chemical resistant drainage systems
  • Joint flexibility enables pipeline settlement during construction and differential ground movement
  • Suitable for above ground and underground drainage applications