Abstract High-density polyethylene (HDPE) pipes are widely used in urban natural gas pipelines. Thermal butt fusion (BF) welds are the weakest components of pipelines. Welding joint aging causes degradation of the PE thermal BF joint material properties. Using the nonlinear ultrasonic technique as a nondestructive testing (NDT) method was proposed for evaluating aging damage. Nonlinear ultrasonic measurements were conducted for HDPE thermal BF joint samples exposed to compression creep. Ultrasonic harmonics are generated due to aging damage. The acoustic nonlinearity parameter β based on the fundamental and second harmonics is calculated. The results indicate that β is sensitive to the variation in HDPE specimens under different aging conditions. This NDT method is useful in tracking microstructural changes in BF joints due to aging during the service process.

中文翻译：

---

高密度聚乙烯天然气管道热对熔接头老化行为的非线性超声评价

摘要 高密度聚乙烯（HDPE）管道广泛应用于城市天然气管道。热对焊 (BF) 焊缝是管道中最薄弱的部分。焊接接头老化会导致 PE 热 BF 接头材料性能下降。提出了使用非线性超声技术作为一种无损检测（NDT）方法来评估老化损伤。对暴露于压缩蠕变的 HDPE 热 BF 接头样品进行非线性超声测量。由于老化损坏会产生超声波谐波。计算基于基波和二次谐波的声学非线性参数β。结果表明β对不同老化条件下HDPE试样的变化很敏感。