TRIBOLOGICAL BEHAVIOR OF THREAD COMPOUND FOR APPLICATIONS IN OIL AND GAS INDUSTRY

N. ZABALA; W. R. TUCKART; P. CASTRO

Foz Do Iguazu

Congreso; TRIBr 2014; 2014

Asociación Brasilera de Metalurgia y Materiales

During the make-up and break-out of the connections, threaded joints are exposed to intense mechanical and tribological solicitations. The connection performance is influenced by its geometry, material properties, surface treatments and thread compound. The aim of this work is to evaluate and characterize the tribological behavior of different thread compounds applied on manganese phosphated carbon steel under low speed and high pressure sliding contact. Four thread compounds were evaluated: one containing lead, zinc and graphite; other lead-free, containing copper and finally, the last two lead-free and containing non-metallic solids. The tribological behavior was analysed by a block-on-ring tribotest. During the test, load varied linearly between 250 N and 7000 N; loading and unloading lasted 14 sec and were performed in opposite directions of rotation to simulate the the make-up and break-out operations. Friction force and load as a function of time were register. Upon completion of the test, wear surfaces were analyzed by SEM, optical microscopy and energy dispersive spectroscopy. The obtained results show that the lead, zinc and copper containing thread compound displayed the best behavior, showing a wear reduction of approximately 20%. These results are in line with previously known oilfield experience. Average COF values around 0.15 were measured and no significant differences between greases were observed; indicating that the wear behavior was influenced by the additive package.