Ultrasonic pattern recognition study of intergranular stress corrosion cracks vs. weld crown reflectors in SS piping. Interim report

Technical Report · Fri Sep 01 04:00:00 EDT 1978

DOI:https://doi.org/10.2172/6433691· OSTI ID:6433691

Rose, J. L.; Singh, G. P.

Pattern recognition techniques for discriminating between geometrical and crack reflector signals obtained during ultrasonic inspection of weld zone in Type 304 austenitic stainless steel piping have been applied to one set of data. Seven welds from four different 4-in diameter pipe specimens containing intergranular stress corrosion cracking (supplied by the GE pipe laboratory through SwRI) were examined ultrasonically. Geometrical reflectors considered in this feasibility study were crown type reflectors only, since they were readily available in the pipe specimens. The ultrasonic inspection was conducted in a pulse-echo mode using a 1.5 MHz nominal center frequency, 3/8-in diameter transducer mounted on a plexiglass shoe with a 45/sup 0/ refracted transverse wave. A version of the Southwest Research Institute pipe weld examination code was used for recording the data. The ultrasonic signals were digitized and stored for further analysis. One hundred fifty-five indications were recorded from seven different welds, four of which were examined from both sides, and three from only one side. The ultrasonic data were correlated with dye penetration tests and ultrasonic examination conducted by SwRI in order to obtain correct training information. The data naturally fell into two categories, cracks and crowns (geometric reflectors). A total of 107 crown indications and 40 intergranular stress corrosion cracking (IGSCC) indications were further analyzed. The pattern recognition analysis indicated that an IGSCC indication was discriminated from a crown indication in about 98% of the cases. The success of the pattern recognition algorithm employed in this study demonstrates the applicability of this technique for solving such important problems as discrimination between IGSCC and geometric reflectors in 304 stainless steel pipe welds. Additional work on other kinds of geometric reflectors is required to establish confidence level in reflector classification analysis.

• Research Organization: Ultrasonics International, Churchville, PA (USA)
• OSTI ID: 6433691
• Report Number(s): EPRI-NP-891
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220200* -- Nuclear Reactor Technology-- Components & Accessories
ACOUSTIC TESTING
ALGORITHMS
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
COOLING SYSTEMS
CORROSION RESISTANT ALLOYS
DATA ANALYSIS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IN-SERVICE INSPECTION
INSPECTION
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MATERIALS
MATERIALS TESTING
MATHEMATICAL LOGIC
NICKEL ALLOYS
NONDESTRUCTIVE TESTING
PIPES
POWER REACTORS
REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
REACTORS
STAINLESS STEEL-304
STAINLESS STEELS
STEELS
TESTING
ULTRASONIC TESTING
WELDED JOINTS