As a common plastic pipe, PVC (polyvinyl chloride) pipe is widely used in various types of construction, drainage, water supply and other piping systems due to its good chemical stability, corrosion resistance, easy processing and economy. However, as a plastic material, PVC pipe has certain limitations in terms of pressure resistance. In order to ensure the long-term safe operation of PVC pipe, it is crucial to understand how much pressure it can withstand.
This article will analyze in detail what pressure can pvc pipe withstand from the aspects of physical properties of PVC pipe, the relationship between working pressure and pressure resistance, standard classification, application scenarios, etc.
Physical properties and pressure bearing capacity of PVC pipes
The pressure bearing capacity of PVC pipes is usually closely related to the physical properties of the pipe type, wall thickness, outer diameter, etc. The main physical properties of PVC pipes include:
1. Tensile strength
PVC pipes have high tensile strength and can withstand a certain external tensile force, but when under pressure, they are mainly affected by internal pressure.
2. Compressive strength
PVC pipes have good compressive strength, especially in thicker wall pipes, which enables PVC pipes to maintain their shape without breaking under certain internal and external pressures.
3. Rigidity and elasticity
PVC pipes are rigid pipes. Compared with some flexible pipes (such as corrugated pipes), they have poor bending resistance and deformation resistance, but when under pressure, PVC pipes can maintain good shape and function.
4. Effect of temperature
Temperature will directly affect the pressure bearing capacity of PVC pipes. As the temperature rises, the strength of PVC pipes may decrease, so in high temperature environments, the pressure bearing capacity of PVC pipes will decrease.
Working pressure and maximum pressure of PVC pipes
The maximum pressure of PVC pipes is not only related to their physical properties, but also affected by factors such as the use environment, pipe size, and service life. In order to standardize design and construction, PVC pipes are usually classified according to their working pressure (working pressure refers to the pressure that the pipe can withstand for a long time under normal working conditions).
Internationally, the pressure level of PVC pipes is usually expressed by PN (nominal pressure), and the unit is “MPa” (megapascals). Different types of PVC pipes are produced at different pressure levels to meet the needs of different uses. Common PVC pipe pressure levels include:
Low-pressure PVC pipe (PN6)
Low-pressure PVC pipes are usually used in places with lower pressure, such as drainage pipe systems. The nominal pressure of this type of pipe is 6 bar (about 0.6 MPa), that is, it can withstand internal and external pressures of about 0.6 MPa.
Medium-pressure PVC pipe (PN10)
Medium-pressure PVC pipes are usually used in general water supply pipe systems with a nominal pressure of 10 bar (1 MPa). This pipe is suitable for home and building water supply systems and can withstand a water pressure of 1 MPa for a long time.
High-pressure PVC pipe (PN16)
High-pressure PVC pipe is generally used for applications requiring higher water supply pressure and some industrial occasions, with a nominal pressure of 16 bar (1.6 MPa). It is suitable for industrial water systems, agricultural irrigation and other scenarios, and can withstand a water pressure of 1.6 MPa.
Ultra-high-pressure PVC pipe (PN20 and above)
For some special applications, such as fire protection pipes, industrial pipe systems, etc., higher pressure bearing capacity may be required. The nominal pressure of this type of pipe can reach 20 bar (2 MPa) or higher. Although the price of ultra-high-pressure PVC pipe is higher, its high pressure bearing capacity enables it to meet high-intensity application requirements.
Factors Affecting the Pressure-Bearing Capacity of PVC Pipes
The maximum pressure that a PVC pipe can withstand is affected by a variety of factors, including the following:
1. Wall Thickness of Pipes
The wall thickness of a PVC pipe directly affects its pressure-bearing capacity. The thicker the wall, the greater the pressure the pipe can withstand. Conventional low-pressure PVC pipes have thin walls and are suitable for occasions with lower pressures, while thick-walled PVC pipes are suitable for occasions with higher pressures.
2. Pipeline Diameter
The diameter of the pipe is also related to the pressure it bears. Pipes with larger diameters usually require thicker walls to withstand the same pressure. Therefore, large-diameter PVC pipes have relatively low pressure-bearing capacity and require higher-grade pipes or thicker pipe walls.
3. Effect of Temperature
As mentioned earlier, the pressure-bearing capacity of PVC pipes is closely related to temperature. In high-temperature environments, the rigidity and strength of PVC will decrease, which will affect the maximum pressure it can withstand. Therefore, the operating temperature of PVC pipes is usually limited to 60°C, and the pressure-bearing capacity will decrease in high-temperature environments.
4. External Environment and Construction Quality
The external environment of the pipe also affects its pressure-bearing capacity. If the pipeline is buried in unstable geological conditions or is subjected to large external forces (such as traffic pressure, groundwater flow, etc.), it may cause the pipeline to rupture. In addition, unqualified construction quality (such as loose connections, unreasonable joint design, etc.) will also affect the pressure-bearing capacity of PVC pipes.
How to choose the right PVC pipe
In practical applications, choosing the right PVC pipe requires considering not only the pressure level according to the specific requirements of the project, but also factors such as the construction environment, temperature changes, and long-term use. The following are several key points to consider when choosing PVC pipes:
1. Clarify the working pressure
When purchasing PVC pipes, you must first determine the working pressure range of the pipe system. For residential water supply systems, PVC pipes with PN10 or PN16 grades are usually selected; for systems that need to withstand higher pressures, such as fire water pipes or industrial pipes, pipes with PN20 or above may need to be selected.
2. Application scenarios of pipes
If PVC pipes are used in water supply systems, especially in warm or tropical areas, it may be necessary to select pipes with better high temperature resistance, or consider the impact of temperature fluctuations when designing. If PVC pipes are used in drainage or sewage systems, pipes with lower pressure grades are usually selected.
3. Pipeline diameter and wall thickness
When designing pipes, the appropriate wall thickness should be selected according to the diameter and use pressure of the pipe. Large diameter pipes usually require pipes with higher pressure grades.
4. Environmental impact
If the PVC pipe is installed underground or in an environment that is greatly affected by external forces, additional protective measures may be required, such as adding an external protective layer or choosing a thickened PVC pipe.
The pressure bearing capacity of the PVC pipe depends on many factors, such as the quality of its material, the diameter of the pipe, the wall thickness, and the temperature. Common PVC pipe pressure levels range from PN6 to PN20, which are suitable for different application scenarios. When making actual selections, the pressure level of the PVC pipe should be reasonably selected according to the specific use requirements and environmental conditions to ensure the long-term safe and stable operation of the pipeline system. At the same time, the construction quality and external environment also affect the pressure bearing capacity of the PVC pipe to a certain extent, so it needs to be taken seriously during the design and construction process.
