The working pressure of the compressed air pipeline is 0.8 MPa; analysis of the design pressure and the valve’s pressure rating.

I. The Relationship Between Operating Pressure and Design Pressure in Compressed Air Piping Systems

In a compressed air system, the working pressure refers to the maximum internal pressure of the fluid under normal operating conditions, while the design pressure serves as the reference pressure used to determine the pipe wall thickness and the pressure‑rating requirements for fittings and valves. The design pressure must be equal to or greater than the working pressure to account for pressure fluctuations and abnormal conditions in the system.

According to relevant codes for industrial piping design, the design pressure is typically taken as 1.1 to 1.15 times the operating pressure, or determined based on the set pressure of the system’s safety valve. For an operating pressure of0.8MPaof the compressed air pipeline, in order to ensure a sufficient safety margin for system operation, its design pressure is typically set to1.0MPaor1.1MPa.

II. Selection of Valve Pressure Rating (Nominal Pressure)

The pressure rating of the valve (i.e., the nominal pressure, PN) must be greater than or equal to the design pressure of the pipeline, ensuring that the valve does not leak or suffer structural failure under the system’s maximum allowable pressure.

• PN10 (1.0MPa）: If the design pressure is set to 1. 0MPa In theory, a PN10 valve could be selected. However, in practical engineering applications, given the start‑stop surges of the air compressor and pressure fluctuations in the pipeline network, the safety margin at this pressure rating is relatively small.
• PN16 (1.6MPa）This is the most common and standardized pressure rating in industrial fluid piping. For systems with a working pressure of 0.8 MPa, selecting valves and fittings rated PN16 provides ample safety margins while ensuring broad market availability, making subsequent maintenance and spare‑part procurement more convenient.

Based on comprehensive engineering practice and safety considerations, it is recommended to select a pressure rating for the valves in this compressed air pipeline.1.6MPa (PN16）.

III. Considerations for the Design and Selection of Compressed Air Piping Systems

• Material matchingSelect an appropriate pipe material—such as carbon steel, stainless steel, or aluminum alloy—based on the service environment, ensuring that the material’s mechanical properties meet the requirements at the corresponding design pressure.
• Safety accessory configurationThe system must be equipped with a safety valve and a pressure gauge. The set pressure of the safety valve shall match the design pressure to prevent overpressure operation.
• Sealing and ConnectionThe sealing gasket at flanged connections shall be selected in accordance with the pressure and the characteristics of the process medium, while threaded joints should be fitted with an appropriate sealing material to ensure the integrity of the piping network.
• Pressure testAfter pipeline installation is completed, strength and tightness tests must be conducted in strict accordance with the relevant codes and standards; only upon passing these tests may the system be put into operation.