GB 50251-2015 English PDFUS$1599.00 · In stock
Delivery: <= 10 days. True-PDF full-copy in English will be manually translated and delivered via email. GB 50251-2015: Code for design of gas transmission pipeline engineering Status: Valid GB 50251: Historical versions
Basic dataStandard ID: GB 50251-2015 (GB50251-2015)Description (Translated English): Code for design of gas transmission pipeline engineering Sector / Industry: National Standard Classification of Chinese Standard: P47 Classification of International Standard: 91.140.40 Word Count Estimation: 199,138 Date of Issue: 2015-02-02 Date of Implementation: 2015-10-01 Older Standard (superseded by this standard): GB 50251-2003 Quoted Standard: GB 50016; GB 50019; GB 50029; GB 50034; GB 50040; GB 50041; GB 50050; GB 50052; GB 50057; GB 50058; GB/T 50102; GB 50116; GB 50140; GB 50183; GB 50264; GB 50369; GB 50423; GB 50459; GB 50470; GB/T 50538; GB 50540; GB 50582; GB/T 50698; GB/T 50818; GB 50991; GBZ 1; GB 150.1; GB 150.2; GB 150.3; GB 150.4; GB/T 5117; GB/T 5118; GB/T 5293; GB 5310; GB 5749; GB 6479; GB/T 8110; GB/T 8163; GB 8978; GB/T 9711; GB/T 10045; GB/T 12459; GB/T 13401; GB/T 14957; GB/T 17493; GB 17820; GB/T 18603; GB/T 21447; GB/T 21448; GB/Z 29328; SY/T 0048; SY/T 0452; SY/T 0510; SY/T 0516; SY/T 0556; SY/T 4103; SY/T 4108; SY/T 4109; SY/T 5257; SY/T 6848; SY/T 6885 Regulation (derived from): Ministry of Housing and Urban-Rural Development Announcement No.734 Issuing agency(ies): Ministry of Housing and Urban-Rural Development of the People's Republic of China; General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Summary: This Standard applies to land new construction, expansion and renovation pipeline engineering design. GB 50251-2015: Code for design of gas transmission pipeline engineering---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.1 General 1.0.1 This specification is formulated to implement the relevant national laws and regulations and policies in the design of gas pipeline engineering, unify technical requirements, achieve advanced technology, reasonable economy, safety and applicability, and ensure quality. 1.0.2 This code is applicable to the engineering design of newly built, expanded and reconstructed gas transmission pipelines on land. 1.0.3 The design of gas pipeline engineering shall meet the following requirements. 1.Protect the environment, save energy, save land, and handle the relationship with railways, highways, transmission lines, rivers, urban and rural planning, etc.; 2 should actively adopt new technologies, new processes, new equipment and new materials; 3 The design scheme should be optimized to determine the economical and reasonable gas transmission process and the best process parameters; 4 The expansion project should make reasonable use of the original facilities and conditions; 5 The phased construction project shall carry out the overall design and formulate the phased implementation plan. 1.0.4 The engineering design of gas transmission pipelines shall not only comply with this code, but also comply with the current relevant national standards. 2 terms2.0.1 pipeline gas pipeline gas Natural gas, coal bed methane and coal-to-natural gas transported by pipeline. 2.0.2 gas transmission pipeline project Projects that use pipelines to transport natural gas, coal bed methane and coal to natural gas. It generally includes engineering content such as gas transmission pipelines, gas transmission stations, pipeline crossing (crossing) and auxiliary production facilities. 2.0.3 Gas transmission station The general term for various process stations in gas pipeline engineering. Generally, it includes the first station of gas transmission, the last station of gas transmission, gas compressor station, gas receiving station, gas distribution station, pigging station, etc. 2.0.4 gas transmission initial station The starting point of the gas pipeline. Generally, it has the functions of separation, pressure regulation, metering and pigging. 2.0.5 gas transmission terminal station The terminus of a gas pipeline. Generally, it has the functions of separation, pressure regulation, metering, pigging, and gas distribution. 2.0.6 gas receiving station gas receiving station Along the gas transmission pipeline, the stations set up to receive gas from the gas transmission branch line generally have the functions of separation, pressure regulation, metering, and pigging. 2.0.7 Gas distributing station Along the gas pipeline, the stations set up to distribute and transport gas to users generally have the functions of separation, pressure regulation, metering, and pigging. 2.0.8 compressor station Along the gas pipeline, a station is set up to pressurize the pipeline gas with a compressor. 2.0.9 underground gas storage Geological structures, gas wells and ground facilities that store natural gas in a certain underground space. Geological structure types include salt cavern type, depleted oil and gas reservoir type, aquifer type, etc. 2.0.10 gas injection station gas injection station A station for injecting natural gas into an underground gas storage. 2.0.11 gas withdrawal station A station set up to extract natural gas from underground gas storage. 2.0.12 Pipe accessories pipe auxiliaries Pipe fittings, flanges, valves, pig receivers, headers, assemblies, insulating flanges or insulating joints and other special pressure-bearing parts of pipelines. 2.0.13 Pipe fittings Elbows, elbows, tees, reducers and pipe heads. 2.0.14 Pipe laying with elastic bending It is a pipeline laying method that uses elastic bending deformation of the pipeline under the action of external force or self-weight to change the direction of the pipeline or adapt to changes in elevation. 2.0.15 pigging system A complete set of equipment for removing condensates and deposits in pipelines, isolating, replacing or conducting on-line inspections of pipelines. These include pigs, pig receivers, pig indicators, and pig tracers. 2.0.16 design pressure design pressure (DP) At the corresponding design temperature, the pressure value used to determine the calculated wall thickness of the pipeline and the size of other components is called the design internal pressure when it is the internal pressure of the pipeline, and it is called the design external pressure when it is the external pressure. 2.0.17 design temperature design temperature The maximum or minimum temperature that the pipe wall or component metal may reach under the corresponding design pressure during the normal working process of the pipeline. 2.0.18 pipeline gas temperature The flow temperature of the gas when it is transported in the pipeline. 2.0.19 operating pressure operating pressure (OP) Under steady operating conditions, the pressure of the medium in a system. 2.0.20 maximum operating pressure maximum operating pressure (MOP) Under normal operating conditions, the maximum actual operating pressure in a pipeline system. 2.0.21 maximum allowable operating pressure (MAOP) The pipeline system follows the provisions of this specification, and the maximum pressure that can be operated continuously is equal to or lower than the design pressure. 2.0.22 relief and blow-down system Facilities for collecting and treating combustible gases emitted during overpressure relief, emergency venting, and start-up, shutdown, or overhaul. The pressure relief venting system consists of pressure relief equipment, collection pipelines, vent pipes and processing equipment or a part of them. 2.0.23 water dew point water dew point The temperature at which the first drop of water is precipitated from a gas under a certain pressure. 2.0.24 Hydrocarbon dew point The temperature at which the first drop of liquid hydrocarbons is precipitated from a gas under a certain pressure. 2.0.25 cold bends cold bends Use a mold to bend the pipe into an angled pipe without heating. 2.0.26 Hot bends After the pipe is heated, it is bent into the required angle on the bending machine. 2.0.27 parallel pipelines Two or more pipelines laid adjacent to each other at a certain distance (less than or equal to 50m). 2.0.28 Line cut-off valve (chamber) block valve station The general term for shut-off valves and supporting facilities of oil and gas transmission pipelines, also known as valve chambers. 3 Gas transmission process 3.1 General provisions 3.1.1 The designed delivery capacity of the gas pipeline shall be calculated according to the annual or daily maximum gas delivery specified in the design commission or contract. When the annual gas transmission volume is adopted, the design annual working days shall be calculated as 350d. 3.1.2 The gas entering the gas pipeline should meet the indicators of the second-class gas in the current national standard "Natural Gas" GB 17820, and should meet the following regulations. 1 Mechanical impurities should be removed; 2 The water dew point should be 5°C lower than the lowest ambient temperature under the delivery conditions; 3 The hydrocarbon dew point should be lower than the minimum ambient temperature; 4 The content of hydrogen sulfide in the gas should not exceed 20mg/m3; 5 The carbon dioxide content should not exceed 3%. 3.1.3 The design pressure of gas pipelines should be determined after technical and economic comparisons based on gas source conditions, user needs, pipe quality and safety factors near the pipelines. 3.1.4 When the gas pipeline and its accessories have taken anti-corrosion measures in accordance with the requirements of the current national standards "Code for External Corrosion Control of Steel Pipelines" GB/T 21447 and "Technical Specifications for Cathodic Protection of Buried Steel Pipelines" GB/T 21448, the corrosion allowance of the pipe wall should not be increased. 3.1.5 Gas transmission pipelines should be equipped with pigging facilities, and the pigging facilities should be constructed in combination with the gas transmission station. 3.1.6 When the inner wall drag-reducing coating is used for the pipeline, it shall be determined by technical and economic comparison. 3.2 Process design 3.2.1 Process design should be based on gas source conditions, transmission distance, transmission volume, characteristics and requirements of users, and the relationship with the capacity and distribution of the established pipeline network and underground gas storage. Determined after technical and economic comparison. 3.2.2 Process design should determine the following contents. 1 The overall technological process of gas transmission; 2 Process parameters and flow of the gas transmission station; 3.The number and station spacing of gas transmission stations; 4 The diameter, design pressure and station pressure ratio of the compressor station of the gas pipeline. 3.2.3 The gas source pressure should be used reasonably in process design. When pressurized transportation is adopted, multi-plan technical and economic comparisons should be carried out in combination with the factors of transportation volume, pipe diameter, transportation pressure, power supply and operation management, and the station pressure ratio of the compressor station should be reasonably selected and the station spacing should be determined according to the principles of economy and energy saving. 3.2.4 The characteristics of the compressor station and the pipeline should match and meet the requirements of process design parameters and changes in operating conditions. Under normal gas transmission conditions, the compressor unit should work in the high-efficiency zone. 3.2.5 The gas transmission station with the function of distribution or distribution should be equipped with gas limit and pressure limiting facilities. 3.2.6 When the gas source of the gas pipeline comes from an oil and gas field natural gas processing plant, an underground gas storage, a coal-to-natural gas plant, or a coalbed methane processing plant, gas quality monitoring facilities should be installed on the intake pipeline of the gas pipeline receiving station. 3.2.7 The strength design of gas pipelines shall meet the requirements of changing operating conditions. 3.2.8 The gas transmission station should be provided with an over-station bypass. 3.2.9 The gas transmission pipelines entering and exiting the gas transmission station must be equipped with shut-off valves. And should comply with the relevant provisions of the current national standard "Code for Fire Protection of Petroleum and Natural Gas Engineering Design" GB 50183. 3.3 Process calculation and analysis 3.3.1 The technical design of the gas pipeline shall at least have the following information. 1 Composition of pipeline gas; 2 The quantity, location, gas supply volume and variable range of gas sources; 3 The pressure, temperature and variation range of the gas source; 4 Requirements of users along the line for gas supply pressure, gas supply volume and their changes. When it is required to use pipeline gas storage for peak regulation, the user's gas consumption characteristic curve and data shall be available; 5 The natural environment conditions along the line and the ground temperature at the place where the pipeline is buried. 3.3.2 The hydraulic calculation of the gas pipeline shall meet the following requirements. 1 When the relative height difference △h≤200m of the longitudinal section of the gas pipeline and the influence of the height difference is not considered, it shall be calculated according to the following formula. In the formula. qv——the flow rate (m3/d) of gas (P0=0.101325MPa, T=293K); P1——the starting pressure (absolute) (MPa) of the calculation section of the gas pipeline; P2——The end pressure of the calculated section of the gas pipeline (absolute) (MPa); d——inner diameter of gas pipeline (cm); λ—hydraulic friction coefficient; Z—compressibility factor of gas; △——relative density of gas; T - the average temperature of the gas in the gas pipeline (K); L——The length of the calculation section of the gas pipeline (km). 2 When considering the influence of the relative height difference of the longitudinal section of the gas pipeline, it shall be calculated according to the following formula. In the formula. α—coefficient (m-1); △h——Elevation difference between the end point of the calculation section of the gas pipeline and the start point of the calculation section (m); n——the number of sub-sections calculated along the gas pipeline. The division of the calculated pipe division is along the direction of the gas pipeline, starting from the starting point, and when the relative height difference is ≤200m, it is divided into a calculated pipe division; hi——Elevation of the end point of each calculated pipe section (m); hi-1——the elevation of the starting point of each calculated pipe section (m); Li——the length of each calculation sub-pipeline (km); g—gravitational acceleration, g=9.81m/s2; Ra——gas constant of air, under standard conditions (P0=0.101325MPa, T=293K), Ra=287.1m3/(s2·K). 3 The hydraulic friction coefficient should be calculated according to the following formula, and the formula in Appendix A should be used when the process calculation of the gas transmission pipeline is performed by hand. In the formula. K——the absolute roughness of the inner wall of the steel pipe (m); d - the inner diameter of the pipe (m); Re - Reynolds number. 3.3.3 The temperature calculation at any point along the gas pipeline shall meet the following requirements. 1 When the throttling effect is not considered, it shall be calculated according to the following formula. In the formula. tx—gas temperature at any point along the gas pipeline (°C); t0——soil temperature at the place where the gas pipeline is buried (°C); t1——Gas temperature at the starting point of calculation section of gas pipeline (°C); e - the base of natural logarithm, should be taken as 2.718; x——the length from the starting point of the calculated section of the gas pipeline to any point along the line (km); K——total heat transfer coefficient from gas to soil in the gas pipeline [W/(m2·K)]; D——outer diameter of gas pipeline (m); qv——the flow rate of gas (P0=0.101325MPa, T=293K) in the gas pipeline (m3/d); cP——Constant pressure specific heat of gas [J/(kg·K)]. 2 When throttling effect is considered, it should be calculated according to the following formula. In the formula. j—Joule-Thomson effect coefficient (°C/MPa); △Px——the pressure drop (MPa) of x-length pipe section. 3.3.4 According to the actual needs of the project, it is advisable to conduct steady-state and dynamic simulation calculations on the gas transmission pipeline system to determine the number of compressor stations, boosting ratio, compressor power and power fuel consumption under different working conditions. The flow rate, pressure, temperature and gas storage capacity of pipelines at each node. According to the needs of system analysis, the calculation time period can be determined by hour or day. 3.3.5 Calculation software for steady state and dynamic simulation should be verified by engineering practice. 3.4 Safe release of gas pipelines 3.4.1 The gas transmission station should set up pressure relief and venting facilities upstream of the inbound block valve and downstream of the outbound block valve. 3.4.2 Vent valves should be installed on the pipe section between adjacent line shut-off valves (chambers) of the gas pipeline, and a vent standpipe or a flange interface for leading the vent pipeline should be reserved in consideration of the construction environment. The diameter of the vent valve should be equal to the diameter of the vent pipe. 3.4.3 Pipelines, equipment and containers with overpressure must be equipped with safety valves or pressure control facilities. 3.4.4 The constant pressure of the safety valve shall be determined after system analysis, and shall meet the following requirements. 1 The constant pressure of the safety valve of the pressure vessel shall be less than or equal to the design pressure of the pressure vessel. 2 The fixed pressure (P0) of the safety valve of the pipeline shall be determined according to the maximum allowable operating pressure (P) of the process pipeline, and shall meet the following requirements. 1) When P≤1.8MPa. The constant pressure (P0) of the safety valve of the pipeline should be calculated according to the following formula. 2) When 1.8MPa< P≤7.5MPa, the constant pressure (P0) of the safety valve of the pipeline should be calculated according to the following formula. 3) When P >7.5MPa, the constant pressure (P0) of the safety valve of the pipeline should be calculated according to the following formula. 4) The constant pressure of the safety valve set by the pipeline with the strength design coefficient of 0.8 should not be greater than 1.04P. 3.4.5 The calculation of the diameter of the relief pipe of the safety valve shall meet the following requirements. 1.The diameter of the discharge pipe of a single safety valve shall be determined according to the fact that the back pressure is not greater than 10% of the discharge pressure of the valve, and shall not be smaller than the diameter of the outlet pipe of the safety valve; 2 The diameter of the discharge pipe connecting multiple safety valves shall be determined according to the fact that the back pressure generated when all safety valves discharge simultaneously is not greater than 10% of the discharge pressure of any one of the safety valves, and the cross-sectional area of the discharge pipe shall not be less than The sum of the cross-sectional areas of the relief branch pipes of the safety valve. 3.4.6 The vented gas should be safely discharged into the atmosphere. 3.4.7 The venting design of the gas transmission station shall meet the following requirements. 1 The gas transmission station shall be equipped with a vent standpipe, and a vent pipe may also be provided if necessary; 2 Natural gas at gas transmission stations should be discharged centrally through the venting standpipe, or it can be discharged in different areas. High and low pressure venting pipelines should be set up separately. unimpeded discharge; 3 When the gas transmission station is equipped with an emergency venting system, the design shall meet the requirement that the pressure in the equipment and pipelines in the station be reduced from the initial pressure to 50% of the design pressure within 15 minutes; 4 For the vent pipeline from the exhaust port of the vent valve to the access point of the vent facility, the specification of the pipe used should not be reduced in diameter. 3.4.8 The venting design of the valve chamber shall meet the following requirements. 1 The valve room should be provided with a vent standpipe, and the vent pipe of the shut-off valve installed indoors should be led to the outside; 2 The valve chamber without a vent standpipe shall be provided with a vent valve or a flange interface reserved for connecting the vent line; 3 When the surrounding environment of the valve chamber does not meet the conditions for venting natural gas, the vent standpipe may not be provided, and the natural gas in the upstream and downstream pipe sections of the valve chamber shall be vented by the adjacent valve chamber or the a......Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB 50251-2015_English be delivered?Answer: Upon your order, we will start to translate GB 50251-2015_English as soon as possible, and keep you informed of the progress. 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