1 Design standard for piping layout
1.1 General
1.1.1 Application scope
1 This standard is universal, and it is applicable to piping layout for chemical plant. When carrying out engineering design, the person in charge of the discipline can make appropriate supplements or adjustments to the provisions of this project according to the characteristics of the project, and then issue this standard for implementation.
2 In addition to this standard, the existing national or industrial standards or specifications on pipeline design shall be implemented as required.
1.1.2 Design principles
1 Piping layout design must meet the design requirements of piping and instrument diagram (PID), be safe, reliable, economical and reasonable, and meet the requirements of construction, operation and maintenance, etc.
2 Piping layout must comply with safety and environmental protection laws and regulations, and inspect fire control, explosion protection, safety protection, environmental protection requirements and other conditions, so that piping layout can meet the requirements of safe production.
3 During piping layout, the flexibility required for thermal expansion & cold contraction shall be considered.
4 For the piping of moving equipment, the natural frequency of the piping shall be controlled to avoid resonance.
5 During piping layout, the piping components shall be in strict accordance with the piping classification table and special fittings table.
6 The piping layout shall comply with the relevant requirements of HG 20546.2 Design standard - Equipment layout for chemical plant.
?
1.2 Piping layout
1.2.1 General requirements
1 The clearance height, channel width and foundation elevation of piping layout shall comply with the provisions in Clause 3 of HG 20546.2 Design standard - Equipment layout for chemical plant.
2 The piping layout shall be designed according to the maximum allowable support spacing specified in the current national standard.
3 Piping shall be laid overhead as much as possible, or buried or laid in trench if necessary.
4 Piping layout shall be convenient for operation, installation and maintenance, and shall not affect the operation of crane. Pipes shall not be laid in the area of the building mounting holes.
5 The installation of supports and hangers shall be considered in the piping layout design, the pipeline shall be close to the existing buildings or structures as possible, but the members of large flexibility shall not bear large loads.
6 Where conditions permit, pipelines shall be arranged in rows. In order to design the support easily, the bottom of bare pipe shall be aligned with the bottom of pipe support.
7 Pipe carriers or supports shall not be used on pipes without thermal insulation layer. Large diameter thin-walled bare pipes and pipes with thermal insulation layer shall be supported by pipe carriers or bearings.
8 Flanges or threaded connections that may cause leakage shall not be set on piping for transporting corrosive media across channels or above rotating equipment.
9 When the piping passes through the separating wall of building for separating highly toxic or explosive medium, casing pipe shall be added, and the gap in the casing pipe shall be filled with nonmetallic flexible materials. The weld on the pipeline shall not be in the casing pipe and shall not be less than 100mm away from the port of casing pipe. Waterproof measures shall be taken at the location where pipeline crossing the roof.
10 Headers of fire water and cooling water and drain pipes are generally buried, and anti-corrosion measures shall be taken on the outer surface of pipes according to relevant regulations.
11 For buried piping, the influence of vehicle load shall be considered, and the distance between pipe top and road surface shall not be less than 0.6m, and the piping shall be laid below the depth of frozen soil.
12 For piping with requirements such as "no pocket", "with slope" and "with liquid seal", piping shall be arranged strictly in accordance with PID requirements.
13 When connecting the branch from the horizontal gas main, the branch shall be connected from the top of the main.
1.2.2 Spacing and installation space of parallel piping
1 The clear distance between parallel piping shall meet the requirements of pipe welding, thermal insulation layer and installation & maintenance of components. The clear distance between protrusions on the piping shall not be less than 30mm. For example, the clear distance between the outer edge of flange and the outer wall of adjacent pipe thermal insulation layer or the clear distance between flanges.
2 For the piping not equipped with flange and thermal insulation layer, the distance between the piping shall meet the requirements of pipe welding and inspection, generally, the distance shall not be less than 50mm.
3 The clear distance between piping shall be appropriately increased for piping with lateral displacement.
4 The clear distance from the protrusion of the piping or the most protruding part of the outer wall of the piping’s thermal insulation layer to the pillar of the pipe rack or frame and the wall of the building shall not be less than 100mm, and the space required for tightening the flange bolts shall be considered.
1.2.3 Exhaust and drainage
1 The high point or low point may be formed during piping layout, so air outlet and drain outlet shall be set up:
1) The minimum pipe diameter of the air outlet at high point is DN15, and the minimum pipe diameter of the drain outlet at low point is DN20 (when the diameter of main is DN15, the diameter of drain outlet is DN15). The minimum pipe diameter of air outlet and drain outlet for high viscosity medium is DN25.
2) The air outlet of gas pipe at high point may be closed by thread cap or blind flange and valve may not be set. Except for the piping on the pipe rack, the pipes with DN less than or equal to 25 may not be provided with air outlet at high point.
3) Non-technical air outlets at high point and drain outlets at low point may not be indicated on PID.
?
2 The air outlets and drain outlets (including those connected to the equipment) required by the technology shall be set according to the requirements of PID.
3 The height of air outlet shall meet the requirements of the current national standard GB 50160 Fire prevention code of petrochemical enterprise design.
4 The discharge point of poisonous and inflammable liquid piping shall not be connected to sewer, but to closed system. As for the vent point of gas heavier than air, the impact on the operating environment and the protection of personal safety shall be considered.
1 Design standard for piping layout
2 Legend of pipes, pipe fittings, valves and special pipe fittings on pipeline layout drawing and isometric drawing
3 Typical legend for heating of adjoining pipes
4 Typical heat tracing legend of temperature limited ribbon heater
