1. Definition and working principle
Pressure piping: refers to the piping system that is subject to a certain pressure inside the piping and is used to transport gases, liquids or vapors. Its working principle is to promote the fluid flow in the pipeline through internal or external pressure, applicable to the need for sustained pressure to promote the fluid transportation scenarios, such as industrial production, water supply, gas supply, heating and other systems.
Non-pressurized piping: refers to piping systems in which the fluid inside the piping does not or almost does not bear internal pressure under normal operating conditions. It usually utilizes gravity flow for fluid conveyance and is designed without considering internal pressure, and is suitable for municipal engineering and infrastructure projects such as drainage systems, sewage treatment, and rainwater collection.
2. Material and Structure
pressure piping: Because of the need to withstand high internal pressure, its material needs to have sufficient strength, pressure resistance and corrosion resistance. Commonly used materials include steel (such as carbon steel, stainless steel), copper, aluminum alloy and high-performance plastics (such as PE, PVC, PP, etc.). Structurally, pressure pipes are usually welded, flanged, heat-fused or electrofused to ensure high sealing and pressure-bearing capacity.
Non-pressurized pipes: Since they do not need to withstand high pressure, their walls are thinner and the main considerations for design are flow rate, flow velocity and corrosion resistance. Commonly used materials include plastic (PVC, PE), concrete, ceramics and so on. In terms of connection, non-pressurized piping mainly uses plugging, bonding or threaded connection, etc., and the design focuses on easy installation and economy.
3. Fluid Characteristics and Conveying Methods
Pressurized Piping: It is suitable for conveying fluids that need to be pushed by a certain pressure, including gases (e.g., natural gas, compressed air), liquids (e.g., water, oils, chemicals), and steam, etc. It is usually used to convey fluids at pressures higher than atmospheric pressure. Fluid is usually transported under higher than atmospheric pressure, with higher flow rate and strict requirements for sealing.
Non-pressurized piping: mainly used to convey fluids that are not subject to internal pressure, usually gravity-driven fluids such as rainwater, sewage, wastewater, etc. Its flow rate is low, and the pipeline is designed with a small slope, relying on gravity to flow.
4. Safety and Maintenance Pressure Pipeline: Due to the risk of rupture and leakage due to the long-term exposure to internal pressure, the safety requirements are high. Regular testing and maintenance are required to ensure their safety, and maintenance costs and technical requirements are relatively high. Pressureless piping: Since it is not under pressure, its safety risk is lower, maintenance is simpler, and the main concern is the smoothness of the piping, prevention of blockage and corrosion.
5. Application ScenarioPressure piping: Widely used in water supply, gas, heating, fire fighting and other systems that require continuous pressure. Non-pressure piping: more suitable for drainage, sewage and other occasions that do not bear internal pressure, such as municipal drainage, sewage treatment, rainwater collection, etc.
