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.

PPR热水保温管接受的负载有内部压力和外部压力，通常内部压力产生的应力是形成PPR热水保温管毁坏的主要缘由，毁坏方式是管壁内的拉应力形成变形过大和决裂，设计的时分，要先按接受内压负载停止计算，选择资料和构造数据，然后再思索外压负载停止设计验算，必要时要修正构造数据。

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热水保温管接受外压负载，毁坏方式是外压负载形成管材变形过大或压屈失稳，设计时要依照外压负载停止计算，来选择资料和构造数据。

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.

外压负载比拟复杂，包括土壤重量和空中产生的静负载，及运输车辆经过时产生的动负载，PPR热水保温管接受负载的机理也是比拟复杂的，由于PPR热水保温管属于柔性管材，在外压负载作用下，管材和四周的土壤会产生“管土共同作用”，也就是说管材和四周土壤来共同接受外压负载。

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.

PPR热水保温管的环刚度实践上是不断不变的，比方de110*0.8Mpa和de315*0.8Mpa的PPR热水保温管，同样重量压力的管道，但环刚度并不是相同的，管材的口径越大，环刚度就会相对削弱，还有气温变化的影响，温度降落，PPR热水保温管的硬度也会增大，环刚度就会变大。

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.

关于PPR热水保温管性能的理解，能够协助人们更好的运用PPR热水保温管，使之发挥更大的价值，而PPR热水保温管厂家在设计和消费时，也会思索PPR热水保温管的环刚度问题，保证管材性能的稳定。

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.