Corrosion Testing at TWI
Almost all materials will corrode if exposed to sufficiently reactive conditions, including as a result of moisture in the atmosphere, seawater, sour service conditions, and many more. However, in many cases, corrosion may be predicted, managed, mitigated against or prevented entirely by the selection of correct materials and conditions along with careful monitoring.
TWI has dedicated small scale testing laboratories for electrochemical and direct exposure tests, and larger facilities for testing specimens under load in sweet conditions, seawater (including cathodic protection), and also laboratories for H2S sour service testing.
Bespoke and Standard Testing
Our experts can evaluate materials corrosion behaviour using relevant techniques according to requirements, including rapid electrochemical testing and longer term direct exposure tests in simulated environments. TWI’s testing can be completed in accordance with internationally recognised standards or developed by our experts as a bespoke test to meet your specific requirements. Testing of components may also involve electrochemical studies and long-term testing in purpose designed configurations. Standard test methods are also employed for routine assessments in accordance with the recognised standards for sensitisation, CPT, CCT, etc
Our testing capabilities include:
- Electrochemical evaluation of materials and coatings
- Salt spray ranking assessment
- Testing of materials under load and with cathodic protection in seawater (including corrosion fatigue)
- Weld corrosion testing to assess weld metal, HAZ and parent material, including with 12-channel electrochemical weld testing to monitor up to 12 different weldments in parallel. Monitoring of the individual weldment regions over extended periods by AC & DC test methods, plus laboratory cells and low flow conditions
- Sour and sweet service testing at ambient pressure or at elevated pressure and temperature in autoclaves (200 bar and 200°C) with constant and variable loads (corrosion fatigue, SSRT and ripple loading all in H2S/CO2, etc)
- Hydrogen autoclave for the study of hydrogen disbondment of weld overlays and cladding, materials embrittlement and hydrogen attack
- Full range of analytical equipment available to assess samples and specimens, including SEM with EDX, EPMA, X-ray diffraction and OES, hydrogen analysis, FT-IR with ATR, DSC, etc, for material chemical analysis of metals, welds and plastics
Testing Methods
TWI undertakes all studies according to strict confidentiality and can test materials using recognised standards (ISO, ASTM, NACE etc) or specifically designed procedures using the following techniques:
Testing under load
- Testing configurations include tensile, four-point bent beam, U-bend, smooth or pre-notched geometries, etc, as appropriate
- Constant-load (dead-weight) ambient and elevated pressure testing
- Slow-strain-rate testing (SSRT)
- Ripple load testing
- Corrosion fatigue (including tests in H2S)
Simulated service environments
- Sour service
- Sweet service testing
- Brines
- Seawater (natural or artificial)
- Hydrogen atmosphere at pressure
Electrochemical testing
- 12-Channel ACM Weld Tester for preferential weldment corrosion
- Crevice-free cells (flushed port/Avesta cells)
- Purpose-designed test cells, including multiple sample test environments
- DC and AC techniques for metals and coatings
- Critical pitting temperature (CPT) and critical crevice temperature (CCT) testing
- Long-term exposure testing with LPR, galvanic current, potential monitoring and AC impedance measurement