A technology for dressing and coating in weld areas on inner pipe surface and a device for its realization have been developed. The referred technology and device can be used to restore coatings damaged in the welding process, reduce hydraulic resistance, and extend service life of trunk pipelines.Currently, special attention is being paid in the oil and gas industry to extending service life of trunk pipelines. This life depends essentially on the quality of corrosion protection (prevention) of outer and inner surfaces of trunk pipelines [1].Various methods have been developed and are being used widely to protect the outer surface of pipes, especially in weld areas. For instance, after dressing of the weld, Trial-L type of thermosetting collar supplied by the St. Petersburg firm Khimbalt is put on it. The remaining part of the outer pipe surface is reliably insulated by what is called the VUS insulation supplied by the Moscow firm Evrotekhstroi. Such a technology helps extend the pipeline service life to as many as 20-25 years, but the cost in this case rises by 20-25%.Protection of the inner surface of trunk pipeline is, however, a more complicated matter [2]. Nowadays, some pipe rolling mills, particularly abroad, coat the inner surface of pipes either with Permacor type of special paint manufactured by the German firm Sika Korrosionschutz GmbH or with sand cement. Such coats not only extend the service life of the pipeline significantly but also reduce loss of power for pumping gas trough the pipe on account of diminution of its hydraulic resistance.However, wide application of inside coats is hindered due to difficulties associated with operations performed after welding.First, this involves "swabbing" of the pipe by running through it a specially made piston (a cleaning device fitted with cup-shaped sleeves and steel brushes) with the help of a pipe-layer and a long rod, purging of the pipe with air, and collection of the dirt [3]. Such a procedure for pipes with an inner coating is inadmissible because it damages the coating, but no other method is available yet. Pipe "swabbing" by three pistons is an indispensable operation stipulated by the Set of Rules for laying trunk pipelines [4].Second, when the butt joints of two trunk pipes having a factory-laid inner coat are welded, the coat in the weld area is destroyed completely. And precisely here begin irreversible corrosion processes.Solution of this problem is pressing when use is made of costly high-pressure pipes having a diameter of 1420 mm and a wall thickness of as much as 36 mm, which the Chelyabinsk Pipe Rolling Mill and Vyksa Metallurgical Works have begun to manufacture.The importance of solution of this problem is associated also with the immediate prospect of hydrogen energy development because on the efficiency of gaseous hydrogen pumping from the point of its production to the consumer depends the economic efficiency of introduction of hydrogen energy.
A structural scheme is examined for a 10.43⋅10 6 -ton strategic underwater gas-storage facility at the base of the Kurily-Kamchatka Trench (Tuskarora Trough).Today, underground storage facilities for gas (UGSF) are widely used in Russia to ensure its uninterrupted delivery to consumers. Let us point out that interruptions develop primarily during seasonal fluctuation in gas demand, especially in anomalously cold winters, during emergency situations involving gas pipelines, when the introduction of new capacities is delayed, and finally, when timely export deliveries of natural gas (NG) are impeded.In this connection, the company Gazprom is building 20 UGSF with an overall commercial-gas reserve of more than 60 billion m 3 in various regions of Russia. These include base UGSF (storage for several months), peak UGSF (storage for several days), and strategic UGSF (long-term storage). They all have a number of significant drawbacks: complexity of orifice-bracing equipment; diffusion losses of gas, which degrade the environment in the region where the UGSF are located; disruption of water-salt exchange in groundwater; and, the need to drill a large number of wells for uniform delivery of NG to the UGSF.These drawbacks have prevented the building of strategic NG reserves. Storage facilities with a high gas pressure to ensure compactness, fail-safe sealing to prevent losses and damage to the ecology of the surroundings, and with the ability to eliminate contamination of the gas and its humidification during significant flooding of the storage facility are required for this purpose. The creation of storage facilities for liquefied NG and the use of deep-water troughs, which make it possible to store gas under pressures to 100 MPa are therefore of practical interest (Russian Federation Patent No. 2263248).The container for deep-water gas storage can be fabricated from thin reinforced polyethylene film, which carries virtually no load due to pressure, since it is the same on both sides of the film during the storage of gas. On the other hand, utilization of such ultrahigh pressure permits the storage facility to contain up to 660 kg of methane per 1 m 3 ; this is of particular importance for the development of hydrogen power, when 83 kg of gaseous hydrogen can be stored in 1 m 3 under this pressure; this is 13 kg more than when liquid hydrogen is stored under normal pressure.A factor of no less importance to the operation of such a storage facility is the automated maintenance of a constant (equal to the initial) pressure in the facility as the gas is consumed; this will appreciably simplify the process of filling the facility with compressed gas and its off-loading for consumption.Let us examine the structural design for a strategic underwater gas-storage facility (SUGSF) to be created at the base of the 9717-m-deep Kurily-Kamchatka Trench (Tuskarora Trough). This trench is 2170 km long, and is, on average, 5.9 km wide with an average slope of 7°.
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