Thermal compensation for non-metallic pipes

For thermal compensation of non-metallic pipes, L-shaped and Π-shaped compensators can indeed be used to address thermal expansion issues. Additionally, expanding joints or bellows compensators can also be considered, as they can effectively address the issue of thermal expansion. As for the issue of an excessive number of such compensators being used in long-distance pipelines, it is possible to consider setting up compensation points in segments and increasing the number of fixed supports appropriately, in order to reduce the total amount of compensating equipment needed and thus achieve a balance between cost and performance. Regarding the heat-resistant polyethylene (PE-RT) piping systems mentioned in the GBT 28799-2020 standard, they do possess a certain degree of thermal stability and heat resistance, but this does not mean that thermal compensation is entirely unnecessary. PE-RT pipes still experience linear expansion or contraction due to temperature changes when in use; therefore, in practical applications, it is still necessary to assess whether thermal compensation measures are required based on the specific engineering conditions and design requirements. Typically, in longer pipelines or scenarios with large temperature differences, it is still necessary to calculate the thermal expansion and consider appropriate compensation methods. .

How is compensation calculated for PE-RT? Considering only PE results in an excessive amount of expansion

For PE-RT pipes, their thermal expansion coefficient is usually higher than that of metal pipes; therefore, the issue of thermal expansion does need to be taken seriously. When performing thermal compensation calculations, the following steps can be followed: 1. **Determine the coefficient of thermal expansion**: PE-RT has a relatively high linear expansion coefficient, typically ranging from 0.15 to 0.2 mm/m·°C. 2. **Calculate the thermal expansion of the pipe**: Use the formula ΔL = α × L × ΔT. Here, ΔL represents the thermal expansion of the pipe in millimeters; α is the linear expansion coefficient of the material in mm/m·°C; L is the length of the pipe in meters; and ΔT is the temperature change in °C. 3. **Design compensation measures**: Based on the calculated thermal expansion, design appropriate compensation measures such as using expansion joints, bellows compensators, or taking advantage of the natural bends in the pipe (e.g., U-shaped or S-shaped arrangements) to absorb the stresses generated by thermal expansion. 4. **Mounting brackets and fixing points**: Install brackets and fixing points for the pipes in a proper manner to control the direction and extent of pipe movement, thereby preventing damage to the pipes caused by thermal expansion. 5. **Monitoring and maintenance**: After the pipeline is put into operation, regularly check whether the pipeline’s thermal compensation system is functioning properly, and carry out any necessary maintenance. Proper calculation and design of thermal compensation measures are essential to ensure the safe and stable operation of PE-RT piping systems. During the design process, actual operating conditions and environmental factors should be fully considered to ensure the reliability of the piping system. .

I. Determining the thermal expansion coefficient of PE-RT pipes The thermal expansion coefficient of PE-RT pipes is a key parameter; it determines the amount of expansion or contraction that occurs in the pipes when temperatures change. According to publicly available information, the thermal expansion coefficient of PE-RT pipes can generally be taken as 0.07 mm/(m·°C). This coefficient indicates that for every 1°C change in temperature per meter of pipe length, the pipe will expand or contract by 0.07 mm. II. Calculating the temperature difference The temperature difference is another important factor in calculating the expansion amount of pipes. It includes changes in the temperature of the medium inside the pipeline as well as changes in the ambient temperature outside the pipeline. During calculation, it is necessary to consider the combined effect of these two temperature changes on the expansion and contraction of the pipeline. Temperature change of the medium in the pipeline (ΔT_in): This refers to the temperature change of the fluid within the pipeline, such as water or hot water. It is necessary to know the highest and lowest temperatures of the fluid in the pipeline in order to calculate the temperature difference. Change in the external ambient temperature of the pipeline (ΔT_ext): This refers to the change in the ambient temperature at the location where the pipeline is installed. It is also necessary to know the maximum and minimum values of the ambient temperature in order to calculate the temperature difference. III. Calculating pipe expansion/contraction: With the thermal expansion coefficient and temperature difference, a formula can be used to calculate the amount of expansion or contraction of the pipe. The formula is as follows: ΔL=0.07L·ΔT, where ΔL is the longitudinal deformation caused by the temperature difference (in mm). 0.07 is the linear expansion coefficient of HDPE pipes (including PE-RT) (mm/m·℃). L is the length of the pipeline (m). ΔT is the temperature difference between the internal and external media during installation and use (°C), and can be calculated as ΔT=0.65ΔT_internal+0.1ΔT_external. IV. Determining the compensation method: Based on the calculated expansion amount of the pipeline, an appropriate compensation method can be determined. For PE-RT pipes, common compensation methods include: natural compensation: where the terrain permits, natural compensation can be achieved by routing the pipes in a winding path; this method is simple and cost-effective. U-shaped tension design: When it is not possible to dig a curved trench in difficult terrain, elbows (such as 45° elbows) can be used to create a U-shaped tension design in order to compensate for the expansion and contraction of the pipes. Compensator compensation: In some construction sites where digging trenches is limited and only straight paths are possible, compensators (such as stainless steel compensators) can be used to counteract the thermal expansion and contraction of pipes.

How to install fixing brackets for non-metallic pipes? Metal pipes can be welded firmly to pipe supports, but what about non-metallic pipes?

Clamps, U-bolts, and the like can all be used to secure non-metallic pipes