基于超声临界折射纵波的管道应力状态无损测量方法

Nondestructive measurement method of pipeline stress state based on ultrasonic LCR wave

油气管道多年运行后不可避免出现额外变形,现场管道运行维护工作者正面临准确评价危险管段安全裕度的难题,迫切需要可直接测量管道运行工况下应力的手段,为快速准确评价管道安全裕度提供定量的参考数据。利用超声临界折射纵波(LCR波)波速与应力呈定量关系的超声波法是管道运行工况下应力测量的有效方法。本文基于声弹性理论,分析了超声LCR波传播方向平行于加载方向时波传播时间与应力的关系,推导了一定声程下超声LCR波测量变形管道应力的公式,研制了油气管道运行状态下应力的专用超声测量装置;研究了管壁表面两向应力状态测量方法、温度补偿公式、LCR波在弹塑性变形中的响应规律,开展了现场测量应用实践,形成基于超声LCR波的管道应力状态无损测量技术。研究结果为现场变形管道应力的准确测量提供技术手段,为管道运行期间的安全评估提供准确数据,对保障管道安全有着重要工程意义。

It is inevitable that additional deformation will occur after many years of operation of oil and gas pipelines.On-site pipeline operation and maintenance workers are facing the problem of accurately evaluating the safety margin of dangerous pipe sections.It is urgent to measure the on-line stress of pipeline section directly,and to provide quantitative reference data for rapid and accurate evaluation of pipeline safety margin.The ultrasonic wave method,which makes use of the quantitative relationship between ultrasonic LCR wave velocity and material stress,is an effective method for on-line stress measurement.Based on the theory of acoustic elasticity,the relationship between wave propagation time and stress when the propagation direction of ultrasonic LCR wave is parallel to the loading direction is analyzed in this paper.The formula for measuring the on-line stress of deformed pipe section by ultrasonic LCR wave in fixed sound path is derived.A special ultrasonic measuring device for on-line stress of oil and gas pipeline has been developed.The measurement method of biaxial stress state on the tube wall surface,the temperature compensation formula and the response law of LCR wave in elastoplastic deformation are studied.The application practice of field measurement is carried out,and a nondestructive measurement method of pipeline stress state based on ultrasonic LCR wave is formed.The research results provide technical support for the accurate measurement of the on-line stress of the deformed pipeline section in the field,and provide accurate data for the safety assessment of the pipeline during operation,which is of great engineering significance to ensure the safety of pipeline.