High Temperature Hydrogen Attack Inspection

By signal processing and imaging

High Temperature Hydrogen Attack (HTHA) is one such form of degradation which is due to the formation of Methane (CH4) by reaction with carbon in steel. HTHA can occur either in the parent material or in the weld itself and manifests itself in several types of alloys.

HTHA can be detected in a number of ways, but the reliability of some of the techniques is questionable. SGS has developed a specific procedure and approach to identify and monitor HTHA adequately. The methodology developed by SGS Industrial combines advances signal processing and imaging of the results, utilizing advanced techniques like Time of Flight Diffraction (TOFD), Automated Backscatter and Velocity Ratio measurements.


Lavender HTHA-certified operators with experience
The inspection has high reliability and reproducibility
It is possible to detect attack at an early stage
The progress of attack can be monitored in time
Clear presentation of results is possible
Examination is non-intrusive, resulting in cost and time savings
All geometries can be examined
All data are stored for easy and quick reference at any time in the future
It is not possible to predict how long the inspection will last. When indications are found, the research will be expanded
Only during shutdowns


Areas of Application HTHA could be found in process equipment such as Heat Exchangers, Reactors or pipe-work connected to the equipment.
Capabilities SGS-operators have more than 20 years of experience in these HTHA inspections, which results in consistent performance and has resulted in enormous costs savings in inspection of the assets.
Certifications / licences Lavender HTHA ToFD Level III | Phased Array level III | Ultrasonic Testing level III
In-service inspection possible All equipment should be out-of-service.
Preparation Preparation for the inspection is mandatory (cleaning activities, operational out-of-service aspects).
Procedure SGS has developed a specific procedure and approach to identify and monitor HTHA adequately.
Reporting An extensive report of the inspection will be handed over to the client, where substantiated findings are explained. Furthermore, preliminary reports during the inspection will be given.
Techniques Phased Array | Time of Flight Diffraction | Ultrasonic Testing | Velocity Ratio | Frequency Spectrum Analysis | Backscatter

About SGS

SGS is the world’s leading inspection, verification, testing and certification company. We are recognized as the global benchmark for quality and integrity. With more than 95,000 employees, we operate a network of more than 2,400 offices and laboratories around the world.

Non-destructive testing from SGS – ensures the safe and efficient operation of your equipment and assets by detecting defects before they result in severe damage, and assures compliance with international standards.


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