HYDROGEN INDUCED CRACKING (HIC)

Internal cracks caused by material trapped in budding hydrogen atoms are referred to as hydrogen-induced cracking (HIC). It involves the diffusion of atomic hydrogen, the smallest atom, into a metallic structure. Many alloys and metals may lose mechanical properties when a crystal lattice becomes saturated or comes into contact with atomic hydrogen.

Hydrogen-induced cracking (HIC) is a type of degradation that occurs in the oil and gas industry. The hydrogen atom is the smallest of all atoms, and hydrogen attack is similarly subtle and difficult to detect using standard inspection techniques. Hydrogen damage occurs at two temperature ranges: elevated temperatures and ambient and slightly above temperatures. The following information NON-DESTRUCTIVE inspection methods for detecting, quantifying, and tracking this type of damage. The operation entails using advanced ultrasonic techniques to detect HIC and SOHIC, metal loss, and other laminar defects in the vessel shell material. Manual UT, TOFD, Phased Array Ultrasonics, and Automated Combined UT is all UT techniques (Triplex). The best results are obtained when a combination of these techniques is used.

Hydrogen Induced Cracking Inspection in UAEAdvanced Ultrasonic Techniques for the inspection of Hydrogen Induced Cracking (HIC)

When planning inspection surveys on various components, a number of factors must be taken into account. To obtain complete coverage in the area of concern, it is sometimes necessary to use a combination of ultrasonic techniques and possibly other NDT test methods. Advanced Ultrasonic Testing (AUT) encompasses a variety of ultrasonic techniques that may be partially or fully automated.

The following are a list of factors that should be considered prior to specifying the scope of work:

  • Code compliance (ASME/EN/DIN/API)
  • Fitness for Service (Accurate Dimensions for Calculations)
  • Monitoring (Repeatability with Confidence)
  • In-service / Out of Service (Hi-Temperature Applications)
  • Access / Temperature (Specialized Probes / Limitations)
  • Sensitivity Required (Hi-Resolution Required?)
  • Inspection Window & Costs (Time Available and Budget)

Time of Flight Diffraction (ToFD): This technique detects changes in material structure in a single line scan pattern and is ideal for screening welds for the presence of environmental service-related cracking such as HIC/SOHIC. This would be followed by other techniques for further evaluation. It is critical to use proper setups and procedures.

Phased Array Technology (PAUT): PAUT is an excellent tool for assessing HIC damage, whether using a 0° Linear Scan Technique or the more familiar Sectorial Scan (-30° to + 30°). Both of these techniques are depicted in the images below. Once again, proper setup, probe frequency, and focus are critical to examination accuracy.

HIC TOFD and PAUT

Advantages

  • Applicable for base material or welds, ferritic or non-ferritic conductive metals.
  • Can be used on hot surfaces, underwater, or in irradiated environments.
  • Provides both depth and length information.
  • Accurate sizing of defects up to 25mm in depth.
  • Requires minimal surface preparation and can be applied over paint and other coatings.
  • Applicable for under water inspection as well as normal inspection.
  • Inspection data can be stored and analysed offline.