Methodology for Studying the Wear of Drill Pipe Threads during Repeated Making up and Holding under Load

Abstract

Purpose of reseach is to develop a methodology for studying the wear of drill pipe threads during repeated making up and holding under load. Methods. For the research, stand “IRS-1” was used. This stand is a device for creating a torque of up to 80 kNm and transferring it to a made-up pipe. It is equipped with a make-up torque sensor and a control system that performs make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up thread pair. The test procedure for IRS-1 stand consists of the following sequence of actions: before starting the tests, the threaded protectors are removed; the threads on the nipple and sleeve are cleaned of the preservative grease and traces of corrosion by dry wiping and subsequent degreasing; the thread on the nipple is measured according to the measurement chart using a gauge. The gauge is made on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. The gap between the gauge and the thread is measured using a set of probes from 0.01 to 0.09 mm in increments of 0.01 mm, over 0.1 mm to 0.45 mm in increments of 0.05 mm, over 0.5 mm to 1 mm in increments of 0.1 mm. Results. A new tribotechnical stand of IRS-1 model was designed and created, which allows implementing various techniques for studying the wear of drill pipe threads during repeated making-up and holding under load. An important feature of the designed stand is a make-up torque sensor and a control system that perform make-up until the specified tightening torque is achieved or periodically applies the torque to the made-up threaded pair. The maximum torque generated by the stand is 80 kNm. A particular technique was developed. The technique includes the requirements of the API 7G-2 standard and has shown its effectiveness in the study of thread wear of steel drill pipes. To implement the technique, a special gauge was developed on the basis of the threaded surface impression and is a plate with cutouts in the form of a cross-section of four threads. Within this technique, a measurement chart with two selected measurement areas was developed. An algorithm for making up a pipe at a uniform speed was created. The algorithm includes three stages. There was developed an algorithm of measurements using reference marks, providing measurements at four points in each selected area. Conclusion. The results obtained can be used to create resource-saving technologies for processing ingot, powder, and nanocomposite materials with different dispersion of phase and structural components that are operated under extreme conditions and states.