Ring stiffness is used to indicate the external pressure resistance of buried PPR hot water insulation pipe. If the ring stiffness of PPR hot water insulation pipe is too small, the pipe may be seriously deformed or destroyed by buckling. If the ring stiffness is too high, too large section moment of inertia will be adopted, which will lead to too many materials and increase the cost.

The load that PPR hot water insulation pipe receives includes internal pressure and external pressure. Usually the stress produced by internal pressure is the main reason for the damage of PPR hot water insulation pipe. The damage mode is that the tensile stress in the pipe wall causes excessive deformation and fracture. When designing, the calculation should be stopped according to the load received by internal pressure, the data of selection and construction should be selected, and then the design test of the load stopped under external pressure should be considered. Calculate, revise the construction data when necessary.

PPR hot water insulation pipe receives external pressure load. The damage mode is that the external pressure load causes excessive deformation or buckling instability of the pipe. The design should stop calculating according to the external pressure load to select data and structural data.

External pressure load comparison is complex, including soil weight and static load generated in the air, and dynamic load generated by transportation vehicles. The mechanism of PPR hot water insulation pipe receiving load is also complex. Because PPR hot water insulation pipe belongs to flexible pipe, under the external pressure load, pipe material and surrounding soil will produce "pipe-soil interaction", that is, pipe material and surrounding soil. To jointly accept external pressure load.

In practice, the ring stiffness of PPR hot water insulation pipes is constant. For example, de110*0.8Mpa and de315*0.8Mpa hot water insulation pipes, the same weight pressure pipes, but the ring stiffness is not the same. The bigger the diameter of pipes, the weaker the ring stiffness will be. There is also the influence of temperature changes. When the temperature falls, the hardness of PPR hot water insulation pipes will increase, and the ring stiffness will increase.

Understanding the performance of PPR hot water insulation pipe can help people better use PPR hot water insulation pipe and make it play a greater value. When designing and consuming PPR hot water insulation pipe manufacturers will also consider the ring stiffness of PPR hot water insulation pipe to ensure the stability of pipe performance.