General requirements for pipeline layout design

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(1) The pipeline layout design shall meet the requirements of the piping and instrumentation diagram. (2) The pipeline layout should be planned comprehensively to ensure safety and reliability, as well as economic Rationality; it must also meet the requirements for construction, operation, and maintenance, while striving for an orderly and aesthetically pleasing appearance； (3) When determining the orientation and laying method of the pipes entering the device (unit), coordination between the interior and exterior aspects should be ensured ； (4) The installation of plant-wide pipelines within the factory area should be coordinated with the various installations (units), roads, buildings, and structures present there. Generally, pipe racks are designed along the factory roads to minimize intersections between pipelines and railways as well as roads ； (5) Pipelines should be installed overhead or on the ground ； In special cases, it can be laid in a trench ； (6) Pipelines should be arranged in rows. Pipes on the ground should be laid on pipe racks or pipe supports ； (7) When arranging pipes on pipe racks or pipe supports, it is advisable to ensure that the vertical and horizontal loads acting on the pipe racks or pipe supports are balanced ； (8) A 10%–30% margin should be reserved on the plant-wide pipe racks or pipe supports (including those passing through culverts), taking their loads into account. A 10%–20% margin should be reserved for the main corridor pipe supports of the installation, taking their loads into account ； (9) The layout of pipelines with special requirements regarding distance, angle, elevation differences, etc., as well as large-diameter pipelines, shall comply with the requirements of the equipment layout design ； (10) The piping layout shall not hinder the installation and maintenance of equipment, pumps, and internal components, nor the passage of fire trucks ； (11) The piping layout should provide the piping system with the necessary flexibility. While ensuring the flexibility of the pipeline and keeping the forces and torques exerted by the pipeline on the equipment and pump nozzles within acceptable limits, the pipeline should be as short as possible with as few components as possible ； (12) The placement of support points should be considered simultaneously with pipeline planning. It is advisable to utilize the natural shape of the pipeline to achieve self-compensation ； (13) The pipeline layout should be arranged in a manner that either increases or decreases in elevation step by step, in order to reduce the formation of air pockets or liquid pockets. Otherwise, venting and draining should be provided according to operational and maintenance requirements. The piping layout should minimize \"blind loops\"” ； (14) When a pipeline for gas-liquid two-phase flow is divided into two or more branches, the piping layout should take symmetry into account or meet the requirements of the piping and instrumentation diagram ； (15) Pipelines, except for those that need to be connected to valves, instruments, equipment, etc. using flanges or threads, shall be connected by welding ； Flanges, threads, or other detachable connections should be considered in the following situations: A) When disassembly is required for maintenance, cleaning, or purging ； B) Lined pipe or jacketed pipe ； C) Piping composed of two sections of different materials that are not suitable for welding connection ； D) Pipe connection points where on-site heat treatment of welds is difficult ； E) Galvanized pipes with a nominal diameter of 100 mm or less ； F) Position of the blind plate or \"8\"-shaped blind plate ； (16) The gas branch pipe should be connected from the top of the main pipe ； (17) Pipelines for toxic media shall be connected by welding; flange or threaded connections shall not be used unless there are special requirements. Pipes carrying toxic media should be clearly marked to distinguish them from other pipes, and such pipes must not be laid underground ； (18) When installing pipes for solid materials or pipes containing solid materials, the pipes should be as short as possible, with as few bends as possible, and without any dead corners ； (1) The connection between the solid material branch pipe and the main pipe should be made at an angle in line with the flow direction of the medium, with the angle not exceeding 45° ； (2) The bending radius of the elbows on solid material pipelines shall not be less than six times the nominal diameter of the pipeline ； (3) Piping for slurries containing large amounts of solid material and piping for high-viscosity fluids should have a slope. (19) Branch pipes should not be installed at areas on the vibrating pipeline where bending moments are high ； (20) At the bends in pipes prone to vibration (such as the outlet pipes of reciprocating compressors and reciprocating pumps), elbows with a bending radius of not less than 1.5 times the nominal diameter should be used. The branch pipe should be connected obliquely in the direction of the fluid flow ； (21) When a branch pipe with a nominal diameter of 40 mm or less is connected to a pipe where vibration may occur, reinforcement measures shall be taken at the connection point, regardless of whether there is a valve on the branch pipe ； (22) Horizontal pipes operating under gravity should have a slope of not less than 3‰ in the direction of fluid flow ； (23) When pipes pass through the floor, roof, or walls of a building, sleeves should be used, and the gap between the sleeve and the pipe must be sealed. The diameter of the sleeve should be larger than the outer diameter of the pipe’s insulation layer, and must not affect the thermal displacement of the pipe. The welds on the pipe shall not be inside the sleeve, and shall be at least 150 mm away from the end of the sleeve. The sleeve should be 50 mm above the floor slab and roof surface. A rain cover should be installed when the pipe passes through the roof. Pipes should not pass through firewalls or explosion-proof walls ； (24) When installing corrosive media, toxic media, and high-pressure pipelines, care should be taken to prevent harm to personnel and equipment resulting from leaks at flanges, threads, gasket seals, etc. Leak-prone areas should be avoided above walkways or pumps; otherwise, safety protections should be installed ； (25) For pipes with insulation, pipe supports should be provided at pipe piers and pipe racks. For pipes without insulation, pipe supports may not be installed if not required. When the thickness of the insulation layer is 80 mm or less, a 100 mm pipe support should be used ； When the thickness of the insulation layer is greater than 80 mm, use 150 mm pipe supports ； When the thickness of the insulation layer is greater than 130 mm, use pipe supports that are 200 mm in height ； Insulated pipe supports should be used for insulated pipes ； (26) When there is a large elevation difference in the plant area, the installation of pipelines throughout the plant should take this elevation difference into account, with the elevation of the pipe galleries being adjusted at appropriate locations. The minimum slope of the pipeline should be 2‰. The pipe slope change point should be located at a turn or near a fixed point ； (27) For pipelines that cross or pass through the plant area over railways or roads, no pipeline components such as valves, metal bellows compensators, flanges, or threaded joints shall be installed at the crossing or passing sections ； (28) For buried pipes subject to thermal displacement, retaining piles can be installed if the pipe strength permits; otherwise, thermal compensation measures should be adopted.