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Corrosion damage to flanges and gaskets cause problems in many industries.

Often the problem is only discovered when a bolted joint leaks and at this point it is much more difficult to repair and reseal the joint. Understanding why corrosion occurs and the best gaskets to combat it are important to maintain asset integrity and prevent leaks. 
NACE define corrosion as “The deterioration of a material (usually a metal) that results from a chemical or electrochemical reaction with its environment”. In a gasket/bolted joint application if either the material of the gasket or flange corrodes this will effect the sealing capability of the joint and over time can result in leakage. This then results in wider impacts such as: 

  • safety issues
  • loss of production
  • unplanned maintenance
  • environmental problems
  • reputational damage 
  • plus the associated costs in dealing with these problems. 

There are many types of corrosion but the two common types that effect gaskets in flanged connections are galvanic corrosion and crevice corrosion. Although the mechanisms that cause them are different they can often occur at the same time on a bolted joint.

Galvanic corrosion

This is caused when you have two dissimilar metals in an assembly that are electrically connected in an electrolyte (typically sea water). The dissimilarity in metals can be between the gasket and the flanges or two flanges of dissimilar metals. One material becomes an anode and corrodes more quickly than expected and the other material acts as a cathode and corrodes slower than it would alone. 

The gasket related factors that have a particular impact on the corrosion rates are:

  • the difference in electrode potential between the metals
  • the geometry i.e. the ratio of the size of cathode to the anode. 

Good Practice

To avoid creating galvanic corrosion:

  • The materials of the gasket should always be matched to the materials of the flange.
  • Using the non-conductive (non-graphite) material Thermiculite in spiral wound gaskets reduces the propensity for corrosion. 
  • Use high purity sealing materials
  • Active anti-corrosion chemical coatings on the gasket

Crevice Corrosion

Differences in electrical potential can also occur within the same piece of metal. When a flange is closed, crevices can be formed between the surface of the gasket and serrations on the flange faces. Chemical changes within these ‘stagnant’ micro-environments can initiate corrosion. 

Good Practice

To avoid creating crevice corrosion:

  • Close the crevices by have soft conformable sealing materials such as Sigma
  • Prevent the media from reaching the crevice by using a barrier or inner ring FRG
  • Active anti-corrosion chemical coatings on the gasket

For more information on sealing in corrosive environments please contact our Applications Engineering Team.



    Corriculite is a spiral wound gasket material designed to provide optimum sealing performance and corrosion resistance in seawater and hydrocarbon services.

    Find Out More »


    Flange Rescue Gasket


    The Flange Rescue Gasket (FRG) can be used for remedial repairs on corroded equipment AND as a preventative solution.    

    Winner of the NACE Corrosion Innovation Award.

  • SABIC enhances workforce skills with The Academy Of Joint Integrity
    SABIC enhances workforce skills with The Academy Of Joint Integrity
  • Thermiculite® High Temperature Material – Invincible against Heat.
  • Change™ Gasket – Our best gasket yet - proven to perform 60% longer!
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