What are nominal pressure, working pressure and design pressure?
1. What is PN (MPa) - the nominal pressure?
The reference values related to the pressure resistance capacity of pipeline system components refer to the design specified pressure related to the mechanical strength of the pipeline elements. The nominal pressure is generally represented by PN.
Nominal pressure - The pressure resistance strength of the product at the reference temperature, denoted by PN, with the unit: M Pa.
(2) Reference temperature: The reference temperature varies depending on the material. For example, the reference temperature for steel is 250°C, EPDM gasket reference temperature is 120 degreee
(3) Nominal pressure 1.0 Mpa, denoted as: PN 1.0 Mpa
II. What is Work pressure?
It refers to the maximum pressure that must be applied to the pipeline system for its safe operation, which is determined based on the highest working temperatures of the various levels of the pipeline's transported medium. The working pressure is generally denoted by Pt.
III. What is design pressure?
It refers to the maximum instantaneous pressure acting on the inner wall of the water supply pipeline system. It is usually calculated as the sum of the working pressure and the residual water hammer pressure. The design pressure is generally denoted by Pe.
IV. Test Pressure
The pressure that pipelines, containers or equipment are required to reach for conducting pressure resistance and air tightness tests. The test pressure is generally denoted by Ps.
V. Relationship between Nominal Pressure, Working Pressure and Design Pressure
The nominal pressure is a fictitious pressure artificially set for the convenience of design, manufacture and use. The unit of this nominal pressure is actually pressure, which is the common term in Chinese, and its unit is "Pa" rather than "N". The nominal pressure in English is "nominal pressure" - "in name or form but not in reality" (nominal, but not real). The nominal pressure of a pressure vessel refers to the nominal pressure of the pressure vessel flange. The nominal pressure of the pressure vessel flange is generally divided into 7 grades, namely 0.25, 0.60, 1.00, 1.60, 2.50, 4.00, and 6.40 MPa. The design pressure is equal to 1.5 times the working pressure.
The work pressure is derived from the hydraulic calculation of the pipeline network. 1 MPa = 10 bar (bar) = 10.2 kg/cm² = 100 N/cm²
VI. Relationship
Test pressure > Nominal pressure > Design pressure > Working pressure
Design pressure = 1.5 times Working pressure (usually)