Modernization of pipe joints in machines and equipment of oil and gas fields

Introduction The problem of tight joint of pipelines and high pressure hoses (HPH) applied in various fields of human livelihood is considered. Special aspects of the high-pressure pipelines operation in the equipment of the oil and gas complex is as follows. At ambient temperatures below minus 50ºC, it is needed to transmit thousands of tons of stratum fluids heated up to 200-250ºC and containing aggressive media, abrasive and highly mineralized water. Materials and Methods. Various designs of metal seals applied in high pressure pipe connections are considered. Joints widely used for pipelines do not withstand pressures higher than 20-60 MPa. With that, in pipelines of the oil-industry equipment, pressure may exceed 100 MPa. A key feature of applying joints in question is to reduce their strength with increasing the diameter. These detriments confine the scope of use of the above-mentioned sealing schemes. It makes field repair of such joints, for example, during operation of oil and gas equipment, practically impossible. In this case, the use of quick connectors (Q/C) is required, for disassembling of which it is ample to have the keys. Research Results. For the solution to the specified problems, a principally new scheme of connection sealing for pipelines and HPH is developed and patented. The key element of the patented device is a stepped bushing which reliably seals the connection of pipelines and HPH. The stepped bushing (sealant) should be made of high-alloy steel by analogy with the joint in the flange couplings, and it can be hardened which will allow for increasing the strength of the connections in question and using them under low temperature conditions. Discussion and Conclusions. The comparative analysis of the sealing elements designs shows advantages of the proposed sealant. For its practical application, it is needed to optimize the shape and dimensions of the stepped bush in order to provide for leaktightness at given pressures, and, besides, to determine the required thread pull force to ensure safe performance of the unit.