IMPROVING WEAR RESISTANCE OF THREADED JOINTS BETWEEN PUMP-COMPRESSOR STEEL PIPES WHEN APPLYING MINERAL COATING

Abstract

A new technology of developing mineral coatings on metal surfaces was used to create wear-resistant layers on threaded joints between pump-compressor steel pipes. Comparative studies were conducted, and operational life of threaded joints between pump-compressor steel pipes was determined for the joints before and after applying mineral coating. The method used to determine operational life of a pipe’s threaded joint consisted of performing multiple screwing-loosening tests of pump-compressor pipe’s lock registering torque at every test stage and determining tension with the help of screw pitch gages. The following measurements were taken: - geometrics of pump-compressor pipe’s threaded joint’s profile before and after the tests were conducted; - value of tension depending on the quantity of test cycles; - screwing-loosening torque measurement. As the result of the tests, it was concluded: 1. The sleeves with a hardening mineral coating the maximum value of wear-and-tear is demonstrated during the first 12 test cycles and is by far less than that of the sleeves without such coating. 2. The threaded part of the sleeves with mineral coating shows the absence of a running-in stage. 3. The survey of how screwing corresponds to loosening of the threaded joints of pipes with mineral coating throughout all the test cycles demonstrates a stable operation of threaded joints. 4. The hardening mineral coating increases wear resistance of a threaded joint to wearing loads by 2.5-3 times and is able to provide a predictable number of screwing-loosening cycles up to 100 cycles on condition that pump-compressor pipes’ operational requirements are observed.