核电站用PE-HD管水压试验压力变化规律研究

Study on Pressure Variation of PE-HD Pipes for Nuclear Power Plants in Hydrostatic Test

基于高密度聚乙烯(PE-HD)松弛模量方程、管道长时力学模型和水的状态方程,研究了PE-HD管水压试验压力变化规律,讨论了管道端部约束类型、保压时间和温度的影响。研究发现,约束类型对压力变化基本无影响;增加保压时间能有效降低压降和压降速率,提高试验的稳定性;随着温度的升高,PE-HD管水压试验的压降减小,温度和压降大致呈线性关系。

The stress relaxation normally occurs during the hydrostatic test of PE-HD due to the viscoelasticity,which leads to a change in internal pressure. This work focused on a study on the law of pressure variation during the hydrostatic test of PE-HD on the basis of the relaxation modulus equation of PE-HD,the long-term mechanical model of pipes and the state equation of water. The effects of the constraint types of clamp and the pressure holding time and temperature on pressure variation were also investigated. The results indicated that there was no effect from the constraint types on the pressure,but the increase of pressure holding time could effectively suppress the pressure decrease and decline rate. As a result,the test stability was improved. The pressure in the hydrostatic test of PE-HD was reduced with an increase in temperature,and there was a linear relationship observed between the temperature and the decline rate of pressure.