Technologies
- Material Properties

Corrosion

Almost all materials will corrode if exposed to sufficiently reactive conditions. This can include moisture in the atmosphere, seawater, sour service conditions and many more. The estimated direct cost of corrosion for the USA alone in 1998 was $276 billion.

However, in many cases, corrosion may be predicted, managed, mitigated or prevented entirely by the selection of correct materials, conditions and careful monitoring.

TWI has dedicated laboratories for electrochemical and direct exposure small scale tests, larger facilities for testing specimens under load in sweet conditions, seawater (including CP), plus laboratories for H₂S sour service testing. Evaluation of materials corrosion behaviour is undertaken by relevant techniques covering rapid electrochemical testing and longer term direct exposure tests in simulated environments. Testing is in accordance with internationally recognised standards or developed by our experts in conjunction with client requirements as part of our corrosion services.

Standard test methods are also employed for routine assessments in accordance with the recognised standards for sensitisation, CPT, CCT etc. Testing of components may also involve electrochemical studies and long-term testing in purpose designed configurations.

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 with 12-channel electrochemical weld tester for monitoring 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 for the oil & gas sector 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 for the petrochemical, chemicals and power generation sectors.
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

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, 4-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

For more information, please contact us.