PSI - Issue 20

Yakov Mikhailovich Andreev et al. / Procedia Structural Integrity 20 (2019) 167–173 Yakov Mikhailovich Andreev et al. / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction A significant part of the unified gas system in Russia was created in the early 1950s and in the late 1980s, which are mainly located in the central part of Siberia in the temperate climate zone. Recently, new hydrocarbon deposits located in the Arctic and Subarctic zones of the Russian Far East have been intensively explored. On the basis of long experience from the beginning of the 1970s in the operation of gas pipelines located in the largest region of the Russian Federation by occupied space, the Yakutsk gas production center is being created in the Republic of Sakha (Yakutia). Against the background of the development of the Arctic, on the western part of the territorial subject of Russia in the Republic of Sakha (Yakutia), the Yakut Gas Production Center is being created, which will be the base for the formation of the internal gas transmission network and resource base for the Power of Siberia gas trunkline. Taking into account the extremely difficult climatic conditions, poor development of the road transport and energy infrastructure of this region of Russia, the latest innovations in gas production management technologies, transportation and providing timely forecasts of incidents in which the risk of human error will be at a minimum level will be used. The main reason for these innovations is not only the reduction of incidents resulting from human errors, but also the invaluable experience in operating the existing gas pipelines of this region in the difficult climatic conditions of the permafrost zone, built since the beginning of the 1970s, the total length of which is more than 3130 km. One of the priority tasks for early warning of unplanned stops of the design work of gas pipelines operating in the permafrost zone is to ensure the cold resistance of the gas pipe material in conjunction with unstable permafrost soils. The study of the problem of ensuring the strength and destruction of gas pipelines are devoted Ajnbinder A.B., Kamershtejn A.G. (1982), Bolshakov and Andreev (2014), Bolshakov and Prokopyev (2016), Oswell J.M (2011).

Nomenclature D outside

outer diameter of the pipeline;

Ψ 3

coefficient taking into account the biaxial stress state of the metal of pipes;

c 1

coefficient reflecting the category of pipeline sections;

k reliability coefficient of reliability of pipes; R 2

the standard value of the yield strength of the pipeline material;

P

is the operating pressure of the pipeline; internal diameter of the pipeline; nominal thickness of the pipeline;

D internal δ nominal

α

is the coefficient of linear expansion of the pipe material;

Δ t

is the temperature difference.

2. Specifics multi-year-frozen grounds in the area of the main gas pipelines in the Republic of Sakha Yakutia It will consider the features of the construction and operation of gas pipelines in difficult conditions of the permafrost zone, where the main adverse factor is the variable bearing capacity of permafrost soils. At subzero temperatures, permafrost soils experience extremely high loads without significant changes in terrain, and when the temperature approaches zero, they lose their bearing capacity. Re-freezing of these soils causes them to swell and crack, which leads to incidents or accidents in gas pipelines. To protect against such soil deformations, it is necessary to apply special protection measures, including the processing of structural and technological solutions. On permafrost soils, mainly two types of solution are used: installing the gas pipeline on pile supports and laying the gas pipeline in an embankment with a thermally insulating pad. The bearing capacity of soils in summer and winter is variable. In winter, permafrost soils form a single monolithic “plate”, which positively affects the operation of heavy machines, so the gas pipeline is laid in the winter. Based on welding logs, gas pipeline laying and filling acts, the average ambient temperature during gas pipeline installation is in the range from subzero –20 to subzero –45 ° С . After the gas pipeline reaches its design capacity, the surface temperature of the pipes in summer can reach up to plus 10 ℃ .