Detection of hydrogen attack in base metal and weld HAZ
- NDE Associates, Inc., Houston, TX (United States)
- Chevron Research and Technology Co., Richmond, CA (United States)
Hydrogen attack is known to occur in C-1/2Mo steels operating at high temperature and pressure in the hydrogen environment. The attack occurs in the base metal as well as in the weld heat affected zone (HAZ) of vessels and pipes. Hydrogen attack reduces the strength and toughness of steel and, if left undetected, can lead to component failure. Failures can be avoided by timely application of reliable and sensitive nondestructive techniques. Ultrasonic techniques were developed and applied to detect hydrogen attack in both the base metal and weld HAZ attack. Ultrasonic backscatter and velocity ratio techniques were applied for detection of base metal attack. These techniques are, however, not suitable for detection of HAZ attack. Conventional shear wave examination is currently used for HAZ inspection. This method can detect large cracks but is not sensitive to detect microcracks produced by hydrogen attack. A combination of two techniques was developed for detection of HAZ attack. These techniques are: contact focused angle beam S-wave and pitch-catch L-wave. The first technique focuses the beam using an acoustic lens while the second technique uses the intersection point of the two pitch-catch beam axes to illuminate the HAZ zone. Both the focused and pitch-catch techniques were applied on samples with simulated HAZ attack. The techniques were successful in detecting simulated attack.
- OSTI ID:
- 136791
- Report Number(s):
- CONF-950740--; ISBN 0-7918-1344-4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Measurement of intergranular attack in stainless steel using ultrasonic energy
Measurement of intergranular attack in stainless steel using ultrasonic energy