1. What is the nominal pressure PN (MPa)?
The reference value relating to the pressure resistance of the piping system component refers to the design given pressure in relation to the mechanical strength of the piping component. The nominal pressure is generally expressed in terms of PN.
1) Nominal pressure - The compressive strength of the product at the reference temperature, expressed in PN, in units of MPa.
2) Reference temperature: The material has different reference temperatures. For example, the reference temperature of steel is 250°C.
3) The nominal pressure is 1.0Mpa, recorded as: PN10.

2. What is working pressure?
It refers to the maximum pressure specified for the maximum operating temperature of the pipeline transport medium for the safe operation of the pipeline system. Working pressure is generally expressed in Pt.

3. What is the design pressure?
It refers to the maximum instantaneous pressure exerted by the water supply pipe system on the inner wall of the pipe. The sum of working pressure and residual water hammer pressure is generally used. Design pressure is generally expressed in Pe.

4. Test pressure
Pipes, vessels or equipment are subjected to pressure and air tightness tests to determine the pressure to be achieved. The test pressure is generally expressed in Ps.

5. Relationship
Test pressure > Nominal pressure > Design pressure > Working pressure
Design pressure = 1.5 × working pressure (usually)