Evaluation Test Research of DR Inspection System for Circumferential Welds in Long Distance Pipeline

长输管道环焊缝DR检测系统评定试验研究

Digital radiographic(DR)testing equipment has been widely promoted and applied in the inspection of circumferential welds in oil and gas pipelines.In order to establish a comprehensive quality control system for digital radiographic testing and fully evaluate the integrated system inspection ability of equipment,personnel,and processes,a scientific and standardized evaluation method to the system is very necessary.Here investigates the precedents of relevant non-destructive testing evaluation methods at home and abroad,considers the testing characteristics of DR equipment,develops a complete set of DR testing system evaluation procedures.It deeply studies the adaptability methods of program processes from defect production to slicing processing and data statistical calculation for digital radiographic testing evaluation.To check the repeatability and reliability of the detectable system,five process welds with 200 real metallographic defects were fabricated in the laboratory.From the detected results,the DR system has good repeatability in image quality,and the detectable defect size reaches 0.85 mm under achieving 90%detection probability at a confidence level of 95%,the error of detected defect length is±2 mm,and the error of detected defect localization is±5 mm.The qualitative and quantitative detection of defects are accurate and reliable.The test further confirmed the reliable detection ability of the DR detection system,and fully validated the scientific and practical evaluation method designed.The research on the evaluation test method can serve as an important link in the quality control system for the on-site application of digital ray equipment in long-distance pipelines.The designed program,test,and evaluation content can serve as an important basis for the formulation of relevant specifications or standards.

数字射线检测设备已经开始在石油天然气管道环焊缝检测中大规模推广应用,为建立完善的数字射线检测质量控制体系,充分评价设备、人员以及工艺一体化的系统检测能力,需要建立一套科学规范化的评价方法。本工作结合国内外相关无损检测评价方法先例以及DR设备的检测特性,制定了一套完整的DR检测系统评定程序,深入研究了程序流程从缺陷制作到切片加工及数据统计计算等项目对于数字射线检测评价的适应性方法。并制作了五条工艺焊缝,对200个真实缺陷进行金相加工,对检测系统的重复性、可靠性进行了客观、全面的评价。该试验结果中DR系统图像质量重复性良好,在95%置信度下达到90%检出率,缺陷尺寸达0.85 mm,长度定量误差在±2 mm之内,缺陷定位误差在±5 mm之内,缺陷定性及检出定量准确可靠。试验进一步证实了DR检测系统的可靠检测能力,同时充分验证了文章设计的系统评定方法的科学性、实用性。该评定试验的方法研究,可以作为长输管道数字射线设备现场应用质量控制体系的重要环节,设计的程序、试验及评价内容可以作为相关规范或标准制定的重要依据。