Effect of induction heating stress improvement on ultrasonic response from intergranular stress corrosion cracking
Induction heating stress improvement (IHSI) is often performed for the BWR piping weldments in order to reduce the susceptibility of intergranular stress corrosion cracking (IGSCC). Recently, in an US BWR plant, IGSCC was detected where it was not expected because the plant had implemented IGSCC countermeasures, IHSI. The objective of this work is to experimentally document the effect of IHSI on IGSCC detectability. Two IGSCC pipe samples containing a range of circumferential and axial cracks were fabricated from two 12-inch Type 304 stainless steel pipe weldments by the Creviced Pipe Test. Each sample was documented in detail by UT and PT to establish its IGSCC characteristics prior to application of IHSI and I-(Inverse)IHSI. For each sample two separate UT methods were used. One pipe sample was subjected to normal IHSI, in which the pipe OD surface was heated while the ID surface was kept cool by circulating water. The other pipe was subjected to I-IHSI, in which the pipe was heated from the ID surface followed by rapid cooling from the OD surface with water jet spray. After IHSI treatments, the two IGSCC pipe samples were ultrasonically characterized in the exact manner that was done in the initial characterization to determine if there were any noticeable changes in the UT response of the cracks as indicated by their sizes and signal amplitudes. All of the maximum echo height data from the two samples were compared in terms of the effect of the IHSI treatments. There was no statistically significant difference in the echo height due to the treatments. For both cases, the crack sizes measured after the treatments were reported to be larger than those measured before the treatments. Ultrasonic imaging of cracks was carried out by a laboratory immersion technique coupled with an automated scan probe system. The results are expressed by imaging areas of different echo height levels and of depth.
- Research Organization:
- Electric Power Research Inst., Palo Alto, CA (USA); Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)
- Sponsoring Organization:
- EPRI; Electric Power Research Inst., Palo Alto, CA (USA)
- OSTI ID:
- 6082282
- Report Number(s):
- EPRI-NP-7238
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
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42 ENGINEERING
420500 -- Engineering-- Materials Testing
ACOUSTIC TESTING
ALLOYS
AUSTENITIC STEELS
BWR TYPE REACTORS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM-NICKEL STEELS
CONTAINERS
CORROSION
CORROSION RESISTANT ALLOYS
CRACKS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEATING
HIGH ALLOY STEELS
INSPECTION
INTERGRANULAR CORROSION
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MATERIALS TESTING
MODIFICATIONS
NICKEL ALLOYS
NONDESTRUCTIVE TESTING
PIPES
PRESSURE VESSELS
REACTORS
STAINLESS STEEL-304
STAINLESS STEELS
STEEL-CR19NI10
STEELS
STRESS CORROSION
STRESSES
TESTING
THERMAL STRESSES
ULTRASONIC TESTING
WATER COOLED REACTORS
WATER MODERATED REACTORS