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Corrosion Resistant Alloys

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The correct selection of the appropriate CRA material for production and transportation of hydro-carbons can be a complex procedure based on both previous experience and testing. If not carried out properly, the consequences can be severe.

Selection of the right materials is just the beginning! Alloy composition ranges, joining considerations, heat treatment parameters, metallurgy of complex material combinations, degradation mechanisms in service, and many more parameters must also be well understood for successful use of these highly specialised materials.

The industry drivers for our consulting and research activities include cost reduction through development of new materials, improved productivity welding technology, use of 'cheaper' materials in new conditions and new engineering developments e.g. catenary riser systems, flexible risers in mild sour operation etc. This leads to the following demands:

  • New materials and the consequent need to understand their weldability and corrosion behaviour
  • New welding technologies and joining processes requiring establishment of the joint performance 
  • Application of materials in new service conditions or service envelope extension
  • Corrosion fatigue in sour service and high pressure high temperature applications
  • Industry failure occurrences which have wide potential impact necessitating research to understand the underlying mechanisms
  • Single client confidential work for development of new products and designs to maintain technical excellence in the market place

TWI has the unique capabilities for production of test pieces (including a wide range of joining, cladding and surface deposition methods), testing and characterisation of CRA alloys. Capabilities range from manufacturing and testing of laboratory scale test samples to full-scale production components.

TWI has been involved in many important initiatives in the O&G sector regarding CRA materials:

  • Acceptable dilution limits in claddings
  • Solutions for use of dissimilar metal interfaces subsea
  • Implementation of titanium alloys in drilling platforms
  • Determining optimum heat treatment of supermartensitic steels
  • Determining welding and safe operational limits for duplex and superduplex stainless steels
  • Sour service fatigue limits for a wide range of CRA materials

For more information please email: