Tag Archives: сварные соединения
The article is devoted to the issues of safety provision during gas consumption and gas distribution in cities and residential areas. The performed analysis of the literature showed that significant part of the pipelines transporting gas to the residential areas is applied for operation for more than 40 years. The dependency of the number of accidents of gas supplying and gas distributing networks on the increase of the total length of the network determined on the basis of Rostekhnadzor of RF data shows the tendency of emergency situations increase. On the one hand this is connected with the increase of the service life of the pipelines and accumulation of damages in the pipelines material. Moreover, it was found out that control of the residential buildings networks is not under the supervision of the regulatory authorities due to the amendment of norms and regulations in the field of industrial safety.
Due to the fact that operation of gas distribution systems is performed in the quasi-static mode of loading, these facilities do not considered from the point of view of accumulation of damages in the gas pipelines material and there is no applicable regulations regarding its safety operation period. However, from the literary sources it is well known that complex processes occur in the material on micro and macro levels during the operation period of the equipment. This causes accumulation of damages, locally obtaining limiting state, and creates the possibility of brittle failure in case of an emergency situation.
Carried out research showed that thermal expansion distribution coefficient in the area of welded joint of the material of the gas pipelined made of steel 20 is unstable. This means that stress appeared in the result of the strength load is also distributed irregularly. In the result, accumulation of damages in the areas with the increased stress, which locally could achieve the yield limit, occurs faster.
The article describes the possibility of application of nondestructive method of evaluation of the stress state in the welded joints of the gas pipelines which could provide the possibility to register the rate of accumulated damages in the potentially hazardous elements of the gas distribution systems.
The application of magnetic methods at the quality control of welded designs made from increased durability steel
The results of determination of the residual tensions in welded elements from the low-alloyed increased durability steel classes X65 and Х75, received by a method of holes and means of the final element analysis in the ANSYS software are given in this work. The assessment of influence of thermal processing on the level of the residual tensions in welded elements is made. The comparison of values of the tension received by a method of holes and sizes of intensity of the magnetic field of demagnetized has established correlation dependencies for an assessment of tensely deformed condition of welded elements from investigated steel in the initial and thermally processed condition.
The estimation of durability and safety of operation of the welded technological pipeline from a steel 17G1SU in diameter 400 mm with thickness of a wall of 10 mm, loaded with internal pressure 6 МPа, intended for transportation of oil products is made. Dependence of change of limiting bearing ability of the pipeline on operation time in an excited environment is established. Calculation of pressure in a real design with the revealed not through defects is essentially specified. The expediency of application of diagrams of an indestructibility is proved at an estimation of resource characteristics and survivability of the welded equipment from low-alloy steels.
The evolution of gradient of structural and mechanical conditions of welded connections under thermocyclic influence
Laws of formation and evolution gradient structural states of welded connections of a steel of mark 09G2S in the process of welding and the subsequent thermocyclic processing are investigated. Character of change of their mechanical behavior is analysed.
At the temperature surrounding air below normative welding polyethylene pipes for gas main is made on proposed in IPNG SB RAS technological mode. The Efficiency of the technological mode was researched by methods of the checking quality welded join recommended by normative document. It is installed that recommended methods do not allow realistically to reveal the breaches of the technological mode.