【国外标准】 Standard Practice for Examination of Drillstring Threads Using the Alternating Current Field Measurement Technique

5.1 The purpose of the alternating current field measurement method is to evaluate threads for surface breaking discontinuities such as fatigue cracks running along the thread root. The examination results may then be used to determine the fate of the test piece. This may involve re-examination by an alternative technique, immediate scrapping of the test piece, or reworking to remove discontinuities (beyond the scope of this practice). This practice is not intended for the examination of threads for non-surface breaking discontinuities.1.1 This practice describes procedures to be followed during alternating current field measurement examination of drillstring threads on tubulars used for oil and gas exploration and production for detection and, if required, sizing of service-induced surface breaking discontinuities transverse to the pipe.1.2 This practice is intended for use on threads in any metallic material.1.3 This practice does not establish acceptance criteria. Typical industry practice is to reject these connections on detection of a confirmed crack.1.4 While the alternating current field measurement technique is capable of detecting discontinuities in these connections, supplemental surface NDT methods such as magnetic particle testing for ferrous metals and penetrant testing for non-ferrous metals may detect additional discontinuities.1.5 Units—The values stated in either inch-pound units or SI units are to be regarded separately as standard. The values stated in each system might not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from both systems may result in nonconformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.