Arguing – take pressure pipelines as an example; give a clear definition
Thread Content
This post was last edited by shiworkstation on 2018-7-31 08:24. It is known that there is an exhaust pipe that leads directly to the waste gas scrubber, from where the gases are discharged. The normal operating pressure is at atmospheric level. However, there is a shut-off valve on the exhaust system; if this valve is closed due to employee error, the pipeline upstream will have a pressure of 0.3 MPa. Is this maximum operating pressure considered relevant? Is it the pressure from working conditions, or the pressure from emergency situations? ? ) reaches 0.3 MPa; should such a pipeline be considered a pressure pipeline? ?
First, it is necessary to explain the function of this valve. It can be added as a pressure relief valve, a valve for discharging materials, etc. If this valve remains closed during normal operation to allow for natural discharge of materials, and if the upstream equipment cannot generate a pressure source that exceeds the operating pressure, then it doesn’t matter whether the valve is opened or closed. This is only in terms of stress. If it is equipment such as a reactor that involves material mixing ratios, then using this discharge valve to control the amount of mixture is not feasible. If the fluid coming before the valve is a stationary discharge, it does not matter whether this valve is opened or closed. If the fluid flowing before the valve has a power source, closing this valve will cause the pressure to rise; this condition is referred to as \"overpressure\" with regard to the pressure before the valve. In the case of centrifugal pumps, over time the increase in temperature can lead to vaporization, thereby causing production accidents ； Other types of power sources can also potentially cause production accidents. Even further upstream in the production process, it is also possible for production accidents to occur due to control issues with this valve. In summary, it is still necessary to follow the operating procedures; pressure values are merely numbers and cannot be used to make general statements. It is recommended to use the above image, as it provides a clear direction.
For pressure pipelines, the pipe diameter also matters; there’s no need to worry about this issue for diameters smaller than 50. For values greater than 50, a pressure of 0.3 Mpa is theoretically possible, even in the case of pressure pipelines
Normal operation is at atmospheric pressure; that doesn’t count.
The pressure should be set according to the design pressure, right?
It is not considered a pressure pipeline; a pressure pipeline refers to the condition under normal operation, with temporary or immediate pressures not being taken into account
Our usual practice is to use the valve as the boundary: the area ahead of it is considered part of the pressure pipeline, while the area behind it is not.
Pipelines are determined based on the “maximum operating pressure”, not the “design pressure””
The maximum operating pressure in front of the valve and at the valve itself is greater than 0.1 Mpa.G； The nominal diameter is greater than DN25; it is used for transporting gas and is considered a pressure pipeline
What is the diameter of the pipe, and what gas is inside it? If it is compressed air, it should not be considered a pressure pipeline