Improving wear resistance of drill pipe sub thread is a vital task, and finding effective solution for it would much assist oil and gas companies to enhance well construction process. The report presents the results of comparative wear resistance tests for P147/147 and P133/133 subs of the top drive manufactured by OOO «NIGMASH» in Bashkortostan. The tests were performed by OOO «Tatburneft» holding company, a division of PAO «TATNEFT». Both, series and test subs were made from 40X2H4A steel. This report shows the results of metallographic studies and tests for improvement of the parts wear resistance, including the method of final electromechanical hardening (EMH) of the box and pin threads as compared with the conventional method of bulk heat treatment.The researches has developed the equipment, tools and technology for hardening of tool joint thread of drill pipe subs. The performed tests and studies aimed at enhancing efficiency of oil and gas well drilling. Their results are of much interest for oilfield operators, drilling and service contractors, as well as drilling subs manufacturers and repair companies.

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Increasing the durability of drill pipe subs is a pressing problem, a solution to which will improve the efficiency of oil and gas companies when drilling wells. Outer diameter wear, tears on the end surfaces of couplings and the end surfaces of pins, as well as blemishes on external and internal conical rotary-shouldered connections are the most typical defects of the subs. A study and comparative bench tests of the 5135 steel subs with the Z-117 screw were conducted. Testing of the subs with hardening of the work surface by electromechanical processing was done in comparison with the base technology (hardening and high tempering) and carbonitriding. The drill pipe subs were manufactured and hardened by OOO Alexandrovsky Drilling Equipment Plant on the 1М63 machine modernized for electromechanical processing. The comparative bench tests of the drill pipe subs were conducted by OOO Kovrovsky Drilling Equipment Plant on the coupling makeup machine MC-4 by screwing on / unscrewing threaded connections, taking into account the Russian Federation standards and recommendations of the American Petroleum Institute API 7. Electromechanical processing, being one of the method of hardening by a concentrated flow of electric energy of industrial frequency, builds up a gradient layer with the hardness of 52–56 HRC on the surface of the drill pipe subs. The results of the screwing on / unscrewing tests of threaded connections with a toot-joint thread demonstrated high efficiency of carbonitriding and electromechanical processing (500 and more cycles) as a method of increasing hardness of the work surfaces and low efficiency of the current bulk heat treatment (up to 47–66 cycles).