Title: Mechanized Ultrasonic Testing on Girth Weds During Pipeline Construction

Author: J.A. de Raad , F.H. Dijkstar
Institution: RTD, NL

Abstract

The article introduces an inspection solution for girth welds found in pipelines. The mechanization of the inspection process increase the speed of testing and also improves the probability of detection (POD). The described solution is a combination of TOFD with common pulse echo technique. The system can offer unique advantages over the application of pulse echo technique alone.

It has been demonstrated that TOFD can increase POD, in particular for those discontinuities which are difficult to detect because of the unfavorable geometry or orientation. For the weld's root region are appropriate solutions essential to distinguish between relevant weld anomalies and other anomalies such as geometry.

The mechanized UT inspection system is capable of achieving a high POD together with a low false call rate, appropriate anomaly sizing capabilities, and transparent recording of results. The increased use of thin walled, high grade steels justifies the use of ultrasonics in combination with adapted acceptance criteria. For selected applications, the use of the Time of Flight Diffraction technique in addition to the standard mechanized UT probe configuration contributes to the reliability of detection and sizing of anomalies.
(7 Ref, 8 Fig). Review by Rolf Diederichs.

Source:

Materials Evaluation August 1997, Vol.55, Nr.8, S. 890 - 895


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