What should be considered regarding the inlet and outlet piping of centrifugal compressors?

There is a document titled “Code for Pipeline Engineering in Petrochemical Design” on the forum; please search for it as it contains detailed explanations

Article 2.1.1 The piping above and around the centrifugal compressor shall not hinder its lifting and maintenance, and no pipes shall be installed within the range where the rotor can be removed. Sufficient maintenance space should be provided around the centrifugal compressor. Article 2.1.2 Attention must be paid to the piping structure at the inlet of the centrifugal compressor, ensuring that its design facilitates even distribution of the fluid at the inlet. Between the suction pipe elbow and the compressor flange, a straight section of pipe (without any branches) must be provided; the length of this straight section should be at least 3 to 5 times the diameter of the pipe. According to clause 2.1.3, the bending radius of the elbow at the suction inlet should be equal to or greater than 3 times the diameter of the pipe. The elbow at the outlet should be a elbow with R≥1.5DN. Article 2.1.4 When the diameter of the suction pipe does not match that of the suction pipe interface on the compressor, a transition reducer should be used for connection; it is strictly prohibited to use flanges with different diameters for connection. Article 2.1.5: In structures where the slit in the casing is horizontal relative to the shaft, that is, where the rotor is suspended from the upper part of the casing, a longer, detachable section of pipe must be installed when connecting pipes at the compressor’s suction and discharge ports upward or laterally, in order to allow the compressor’s top cover to be lifted. Article 2.1.6: A temporary filter is generally required to be installed on the compressor’s suction pipe (as specified in the PID). To facilitate the installation and removal of the temporary filter, a detachable short pipe (with flanges at both ends) should be installed on the suction pipeline. Clause 2.1.7: The compressor discharge pipeline should be arranged as close as possible to the suction pipeline, so that the suction and discharge pipelines are properly positioned. The valves and instruments on it are concentrated, with the suction and discharge pipes sharing a single pipe rack. Article 2.1.8 The check valve on the discharge pipe shall be installed as close as possible to the compressor. Article 2.1.9 When two or more centrifugal compressors are operated in parallel, airflow collision should be avoided to reduce efficiency losses resulting from parallel operation. At the junction where the outlet branch pipe of each compressor meets the main pipe, it is connected to the main pipe at an angle in the direction of the airflow. Article 2.1.10 For valves arranged centrally, their handwheels shall all face in the same direction. Article 2.1.11 The layout of the suction and discharge pipes of centrifugal compressors shall accommodate changes in the compressor’s thermal displacement. The thrusts and moments generated by the piping system at operating temperature at the compressor’s suction and discharge ports, as well as at the inlet and outlet ports of its intercooler, must be less than the external forces and moments permitted for those ports. Otherwise, the pipe layout should be changed, or pipe pre-stretching and the use of limiting brackets should be employed as a remedy. Article 2.1.12 When the suction and discharge pipes of the compressor are installed on the ground, the minimum height from the bottom of the pipes to the ground shall be 600 mm. Article 2.1.13 Centrifugal compressors used for compressed air shall be located away from sources of pollution, on the downwind side of the wind direction with the lowest frequency throughout the year. The intake should be located in a place where clean, fresh air can be drawn in, and the air intake opening should be at a certain height above the ground. The port should be equipped with a filter cover; when the port is oriented vertically upward, a rain shield should be placed above it to prevent debris and rainwater from entering the pipeline. Article 2.1.14 The air intake pipeline of the air compressor should be arranged as straight and short as possible, with the total length of the intake pipe not exceeding 25 m. Article 2.1.15 The exhaust pipes for compressed air, as well as the intake and exhaust systems of air compressors, shall reduce noise in accordance with relevant regulations. The suction and discharge pipes of the compressor located within the plant should be equipped with sound-insulating layers on their walls if necessary.