RELATIONSHIP BETWEEN NOMINAL PRESSURE, WORKING PRESSURE AND OTHER PRESSURES

# RELATIONSHIP BETWEEN NOMINAL PRESSURE, WORKING PRESSURE AND OTHER PRESSURES

Summary

RELATIONSHIP BETWEEN NOMINAL PRESSURE, WORKING PRESSURE AND OTHER PRESSURES

1、 What is nominal pressure PN (MPA)?

The reference value related to the pressure resistance capacity of piping system components refers to the design given pressure related to the mechanical strength of piping components. The nominal pressure is generally expressed by PN.

(1) Nominal pressure – the compressive strength of the product at the reference temperature, expressed in PN, unit: MPa.

(2) Reference temperature: different materials have different reference temperatures. For example, the reference temperature of steel is

250°C

(3) Nominal pressure 1.0MPa, recorded as: PN 1.0MPa

2、 What is work stress?

It refers to the maximum pressure specified according to the maximum working temperature at all levels of the pipeline medium for the operation safety of the pipeline system. The working pressure is generally expressed by Pt.

3、 What design pressure?

It refers to the maximum instantaneous pressure acting on the inner wall of water supply pipeline system. Generally, the sum of working pressure and residual water hammer pressure is used. The design pressure is generally expressed as PE.

4、 Test pressure

The pressure required for the pressure strength and air tightness test of pipeline, vessel or equipment. The test pressure is generally expressed as PS.

5、 Relationship among nominal pressure, working pressure and design pressure

Nominal pressure is a kind of nominal pressure which is artificially specified for the convenience of design, manufacture and use. This nominal unit of pressure is actually pressure, which is commonly known in Chinese as “pa” rather than “n”. Nominal pressure is nominal pres-s urenomina:l in Name or form but not in reality. The nominal pressure of pressure vessel refers to the nominal pressure of pressure vessel flange. The nominal pressure of 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. Design pressure = 1.5 × working pressure.

The working pressure is obtained by hydraulic calculation of pipe network. 1MPa = 10bar (bar) = 10.2kg/cm2 = 100N / cm2

6、 Relationship

Test pressure > nominal pressure > design pressure > working pressure

Design pressure = 1.5 × working pressure (normal)