NDTnet 1998 Aug, Vol.3 No.8

Abstract

With the development of the deep and superdeep drilling of oil and gas wells, the questions of life, efficiency and reliability of drilling tools become important. One of critical items of drilling equipment is the welded drill bit, which has a complicateddesign and shape. The violation of the welding technology leads to the appearance of defect of the type of pores, chains of pores, lacks of penetration and cracks of various orientation. The occurrence of mentioned defects lowers the wear resistance of drill bit.

The butt welded joints of the item have a technological lack of penetration in the weld root and access from one side only. Therefore, the ultrasonic testing was selected as the main inspection technique.

The preliminary experimental studies were carried out to develop the UT inspection techniques. The studies permitted to select the main types of waves providing information on weld defects of various orientation against the background of technological lack of penetration. During these studies the parameters of testing were selected.

The procedure of non-destructive testing of a weld with technological lack of penetration is implemented as follows: the first UT transducer emitting the lateral and transverse waves is installed in the heat-affected zone of the item being inspected. The lateral and transverse waves receiver is installed on the opposite side of the welded joint. The third UT transducer is placed above the surface of the weld. Its purpose is emission and receipt of longitudinal waves to detect volume defects, as well as receipt of diffracted waves, which are formed when the transverse waves are diffracted from the edge of vertical plane defect. Such a solution permits to carry out a testing of the weld with various wave types; to evaluate the depth of defect location; to classify defects into volume and planar zones.

The special UT system was developed for realizing of testing technology [1]. The selected inspection technique allows to improve the quality and reliability of drill bits.

Reference
1. Arrangement for ultrasonic testing welded joints and wares / Bondarenko Yu.K, Yeskov Yu.B., Shekero A.L. and of others // Patent of Russian Federation No. 2018816, 1994.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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