Processing technology and application of special pipe for petroleum
Petroleum special pipe is mainly used for oil and gas well drilling, oil and gas transmission. It comprises an oil drill pipe, an oil casing pipe and an oil pumping pipe. The tube is mainly used to connect the drill collar and drill bit and drill drilling power transfer. Oil casing is mainly used in the drilling process and after completion of the well wall support, to ensure that the drilling process and completion of the normal operation of the entire well. Oil pumping pipe mainly to the bottom of the oil, gas transmission to the ground. Oil casing is the lifeline to maintain the oil well. Because of the different geological conditions, the stress state of the underground is complex, and the combined action of tension, compression, bending and torsion stresses on the pipe body, which puts forward higher requirements for the quality of the casing itself. Once the casing itself for some reason and damage, may lead to the production of the entire well, or even scrapped.
According to the strength of the steel casing pipe can be divided into different steel grade, that is, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc.. The well condition and the well depth are different, and the steel grade is also different. In the corrosive environment, the casing itself is also required to have corrosion resistance. In the place where the geological conditions are complex, the casing pipe is also required to have anti collapse performance. 27MnCrV is a new type steel production TP110T petroleum pipes, the conventional production of TP110T grade oil pipe steel is 29CrMo44 and 26CrMo4. Relative to the latter two, 27MnCrV contains less Mo elements, can greatly reduce production costs.
27MnCrV steel AC1=736 C AC3=810 C, when the heating temperature of Subcritical Quenching selected at 740-810 DEG C. Select the quenching heating temperature of 780 DEG C, soaking time 15min quenching; tempering after quenching from 630 degrees Celsius temperature, tempering holding time 50min. Because of Subcritical Quenching heating in the alpha + gamma quenching in the two-phase region, retain some undissolved ferrite state, while maintaining high strength and toughness is improved.
There is obvious high temperature temper brittleness after production of 27MnCrV by normal austenite quenching process, which caused the low impact toughness and unstable. After tempering, the rapid cooling method is adopted to avoid high temperature brittleness. By the method of incomplete quenching of austenitic steel in order to effectively improve the harmful elements and impurities, improve the toughness. Heat treatment equipment requirements are relatively strict, the need to add additional cost. At low temperature the lower tempering temperature, reducing stress hardening, thus reducing the quenching deformation, so as to ensure the smooth operation of heat treatment production, provides a good material for the follow-up and thread machining etc..
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