Ultrasonic testing method
First Claim
1. A method of ultrasonically inspecting a selected portion of a metal object having an accessible surface and an opposite surface for flaws using a transducer including an ultrasonic transmitter and receiver where the transducer is moved longitudinally toward and away from said selected portion and laterally essentially parallel to the selected portion, to detect and size flaws in said selected portion and an instrument for recording returned ultrasonic pulse signals received by said receiver where the ultrasonic signals are transmitted in the longitudinal mode within an envelope having a central axis which forms a selected angle with a line perpendicular to a surface of said piece, comprising the steps ofa) determining a reference position on said object in the selected portion on the opposite surface thereof,b) determining a first scanning position on said accessible surface of said object for transmitting an envelope of pulses with the axis thereof directed toward said reference position whereby the points where the envelope of transmitted pulses will intersect said opposite surface on either side of said reference position and define a first longitudinal distance between said points,c) positioning said transducer at said first scanning position and moving said transducer on said accessible surface of said object laterally while transmitting ultrasonic signals into said object with the axis of said envelope directed at said reference position,d) noting on said instrument as indicative of a flaw the first reflected pulse of a reflection of said transmitted signals and noting the location thereof,e) positioning said transducer on said accessible surface so as to detect a first indicated flaw and moving said transducer laterally to size the length of said a first indicated flaw,f) moving said transducer longitudinally on said accessible surface to size the through wall extent of said a first indicated flawg) repeating steps e) and f) for each indicated flaw, andh) recording the position, length and through wall extent of each detected flaw.
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Accused Products
Abstract
A single operation, multi-task, non-destructive testing technique of ultrasonic examination for defect detection, analysis and sizing. The technique utilizes the same angle, mode of propagation, calibration, set-up, and scanning patterns, for all materials, thickness of materials, and configuration of components for which it is applicable. The technique is used to detect, analyze and size planar flaws, such as fatigue cracks, which are connected to the surface opposite that from which the ultrasound is propagated. The technique relies on the fact that specular reflections received from flaws that have penetration into materials will return to the transducer before reflections which are associated with geometric features of the surface to which the flaw is connected. It also relies on the properties of the longitudinal mode of sound propagation at a 65-75 degree angle resulting in reduced specular reflections from opposite wall geometric reflectors such as weld roots and counterbores.
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Citations
25 Claims
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1. A method of ultrasonically inspecting a selected portion of a metal object having an accessible surface and an opposite surface for flaws using a transducer including an ultrasonic transmitter and receiver where the transducer is moved longitudinally toward and away from said selected portion and laterally essentially parallel to the selected portion, to detect and size flaws in said selected portion and an instrument for recording returned ultrasonic pulse signals received by said receiver where the ultrasonic signals are transmitted in the longitudinal mode within an envelope having a central axis which forms a selected angle with a line perpendicular to a surface of said piece, comprising the steps of
a) determining a reference position on said object in the selected portion on the opposite surface thereof, b) determining a first scanning position on said accessible surface of said object for transmitting an envelope of pulses with the axis thereof directed toward said reference position whereby the points where the envelope of transmitted pulses will intersect said opposite surface on either side of said reference position and define a first longitudinal distance between said points, c) positioning said transducer at said first scanning position and moving said transducer on said accessible surface of said object laterally while transmitting ultrasonic signals into said object with the axis of said envelope directed at said reference position, d) noting on said instrument as indicative of a flaw the first reflected pulse of a reflection of said transmitted signals and noting the location thereof, e) positioning said transducer on said accessible surface so as to detect a first indicated flaw and moving said transducer laterally to size the length of said a first indicated flaw, f) moving said transducer longitudinally on said accessible surface to size the through wall extent of said a first indicated flaw g) repeating steps e) and f) for each indicated flaw, and h) recording the position, length and through wall extent of each detected flaw.
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10. A method of inspecting a selected portion of a pipe comprising two sections of butt welded pipe having an outer wall surface and an interior wall surface for flaws using a transducer comprising an ultrasonic transmitter and a receiver and an oscilloscope for displaying received reflected signals where the ultrasonic signals are transmitted by said transmitter in the longitudinal mode within an envelope having a central axis which forms an angle of 65 to 75 degrees with a line perpendicular to the axis of said pipe, comprising the steps of
a) determining a reference position on said pipe on the interior surface at the center of said weld, b) determining a scanning position on said outer surface for transmitting an envelope of pulses with the axis thereof directed toward said reference position whereby the envelope of transmitted signals will intersect said interior surface at points on either side of said weld center and define a first longitudinal distance between said points, c) positioning said transducer at said first scanning position and moving said transducer laterally of said pipe axis on said outer surface of said pipe while transmitting ultrasonic signals into said pipe with the axis of said envelope directed at said weld center line, d) noting on said oscilloscope as indicative of a flaw the first reflected pulse of a reflection of said transmitted signals and noting the position thereof, e) positioning said transducer on said outer surface so as to detect a first indicated flaw and moving said transducer laterally of said pipe on the outer surface while transmitting ultrasonic signals to size the length of said a first indicated flaw, f) moving said transducer longitudinally on said outer surface while transmitting ultrasonic signals to size the through wall extent of said a first indicated flaw, g) repeating steps e) and f) for each indicated flaw, and h) recording the position, length and through wall extent of each detected flaw.
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18. A method of inspecting a section of pipe comprising two sections of butt welded pipe having outer and inner surfaces in the vicinity of the weld for the detection of planar flaws connected to said inner surface using a transducer including an ultrasonic signal transmitter and a receiver and an instrument for recording returned ultrasonic signals received by said receiver where the ultrasonic signals are transmitted in the longitudinal mode within an envelope having a central axis which forms a selected angle with the longitudinal axis of said pipe, comprising the steps of
a) determining the center of the weld on the inner surface of said pipe, b) determining a scanning position on the outer surface of said pipe for transmitting an envelope of pulse at the selected angle with the axis thereof directed toward said weld center on the inner surface of said pipe whereby the points where the envelope will intersect said inner surface at points on either side of said weld center and define a first longitudinal distance between said points on said inner surface, c) positioning said transducer at said scanning position and moving said transducer on said outer surface laterally of said pipe while transmitting ultrasonic signals into said pipe with the axis of the transmitted envelope directed at said weld center, d) noting on said instrument as indicative of a flaw the first reflected pulse of a reflection of said transmitted signals and noting the location thereof, e) positioning said transducer on said outer surface so as to detect a first indicated flaw and moving the transducer laterally of said pipe longitudinal axis to size the length of said a first indicated flaw, f) moving said transducer longitudinally on said outer surface to determine a connection of said a first indicated flaw to said inner surface and to size the through wall extent of said a first indicated flaw, g) repeating steps e) and f) for each indicated flaw, and h) recording the position, length and through wall extent of each detected flaw.
Specification