Measuring and testing – Vibration – By mechanical waves
Patent
1996-08-18
1997-10-14
Williams, Hezron E.
Measuring and testing
Vibration
By mechanical waves
73620, 73624, 73625, 73628, 73641, G01N 2910, G01N 2926
Patent
active
056774907
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an ultrasonic inspection system (testing device) for use in submerged arc welding lines (weld seams) in pipes and metal sheets, preferably panoramic lines of pipeline-pipes, with two inspection head supports of the same construction, which are specularly arranged to the weld line. Each inspection head support comprises at least one inspection head each, which sends a wave sideways from the base material of the pipes and metal sheets into the weld line. Each inspection head support is attached on the surface of the base material, positioned opposite of the root position of the weld line. This invention relates to hand as well as automatically welded lines, i.e, lines of containers.
2. Description of the Prior Art
An ultrasonic inspection system is known from the DE 4030893 A1. With this system, two angle-inspection heads are attached via crack coupling to the base material right and left of the weld line, and is measured through reciprocal acoustic irradiation.
U.S. Pat. No. 4,570,487 shows a process for inspecting cracks in bimetallic, coarse grained specimens. Thereby, a transmitting ultrasonic transducer emits into the specimen to be inspected in such a way that a creep or surface wave is formed on the surface of the specimen, which is opposite to the surface coupled to the transducer. At the crack, this creep wave converts to a volume wave if the crack extends to the surface of the specimen. The volume wave is received by the receiving ultrasonic transducer. During such an inspection, a weld seam in the vicinity of the crack would form a mechanical obstacle, if there is a mechanical deformation that obstructs the motion of the transducer.
U.S. Pat. No. 3,868,847 refers to a process and a device for the ultrasonic inspection of lengthy weld seams which have a central root, gap coupling is used. There is no use for surface waves.
DE-book "Werkstoffprufung mit Ultraschall" (Ultrasonic testing of materials), 1980, p. 475 to 477 and 490 to 500 reports about use of surface waves for testing resistance welded steel tubes. In the book, doubt is expressed whether surface waves or possibly Lamb or plate waves were used.
With the above-ultrasonic inspection system, only a sub-range step of the weld line is seized, unless the two inspection head supports are shifted back and forth synchronically diagonal to the weld line in such a way that a complete acoustic irradiation through the complete weld line is achieved. The synchronization of the two movements appears to be very difficult with the manually executed test as well as with the use of mechanical operating systems. On the other hand, the interpretation of echo indicators, especially the differentiation between flank and root indicators becomes difficult, because the error signals are gained via constantly changing points of wave-entrance. With mechanical operating mechanisms, the time input and electronic resources are extremely high, therefore, the error signals can only be gained via constantly changing wave entrance points. An automatic test is hard to realize with such a known inspection system.
SUMMARY OF THE INVENTION
This is where the invention steps in. It is the task of the invention to further develop the inspection system of the above-mentioned kind. This task is performed without relative motion of the inspection head supports diagonal to the weld line such that, the complete cross-section of the weld line can be seized with sufficient sensitivity and on the other hand, can be differentiated between binding and root errors, as well as the possibility of separate error echos from presentation echos.
The task is solved by departing from the inspection system of the above-mentioned kind in such a way that each inspection head support shows several immersion-technique inspection heads. The inspection heads are attached diagonally to the weld line in such a way, that their points of wave entrance into the base material are as close together as possible and can be adjusted
REFERENCES:
patent: 3552191 (1971-01-01), Heseding
patent: 3575044 (1971-04-01), Gibbs et al.
patent: 3868847 (1975-03-01), Gunkel
patent: 3958451 (1976-05-01), Richardson
patent: 4170145 (1979-10-01), Kennedy et al.
patent: 4375165 (1983-03-01), de Sterke
patent: 4452080 (1984-06-01), McFarland
patent: 4588873 (1986-05-01), Fenn et al.
patent: 4744250 (1988-05-01), Ganglbauer et al.
patent: 5111696 (1992-05-01), Lund et al.
de Sterke, "Automatic ultrasonic inspection of pipeline welds", Dec. 1980, p. 275-284.
Gunther Werner
Heckhauser Helmut
Karbach Bernhard
Schulz Siegmar
Ashraf Nashmiya
Bordas Carol I.
Cheung Noland J.
F. H. Gottfeld Gesellschaft fur Zerstorungsfreie Werkstoffprufun
Williams Hezron E.
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