高钢级天然气管线裂纹缺陷分析

发布时间：2018-03-11 07:42

本文选题：高钢级管道　切入点：裂纹　出处：《西安石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：管道输送已经成为世界范围内最经济、最便捷的石油和天然气运输手段之一,然而随着居民和工业对油气需求的不断增长,以前的低压力、小管径、低强度油气输送管道已经不能满足时代的要求,因此,高压力、大管径、高强度输送管道应运而生。为了确保这些高钢级管道在日常运营中的安全,除了要保证输送管材的质量之外,管道焊接接头的安全状态也至关重要,因为绝大多数管道泄漏事故都是从焊缝处开始的。本文系统阐述了国内外天然气输送管道的现状、发展趋势和论文研究的重要意义。理论方面以X70、X80管线钢为载体,分析了其焊接过程中焊接接头处随温度变化而产生的裂纹缺陷的种类、原因、危害及其相应的预防措施。焊接过程中产生的这些裂纹缺陷会降低焊件结构的强度,其最主要原因就是这些缺陷减小了结构承载横截面的有效面积,同时在缺陷周边区域产生了应力集中,从而造成对焊件的使用性能及寿命产生不利的影响。为了保证管道焊接接头质量,有必要对其进行例行检测,而无损检测能够对生产和运营中的高钢级管道进行检测,以便能够及时发现各种缺陷并采取相应的措施,以减少管道运营期间不必要的损失。超声波检测技术因其操作方便快捷、检测速度快、数据可靠而且成本较低等优点成为对管道焊缝缺陷进行检测的主要手段。本课题实验方面利用数字式超声波探伤仪对自制的仿自然缺陷模拟试块进行实践检测,分析总结了横波斜探头检测技术中探头类型、探头参数(频率、K值、晶片尺寸)、耦合剂和扫查方式对检测灵敏度的影响,并提出了如何选用探头、耦合剂和扫查方式才能更精确地检测焊缝中的裂纹缺陷。测得裂纹缺陷的指示长度和指示高度后以及裂纹偏离焊缝中心线距离后,与预埋理论尺寸进行对比,发现将近90%的实践检测数据误差都在9%以内,从而验证了超声波探伤在高钢级管线焊缝裂纹缺陷检测方面是相当准确和可靠的。
[Abstract]:Pipeline transportation has become one of the world's most economical and convenient means of transportation of oil and gas. However, with the increasing demand for oil and gas from residents and industry, the previous low pressure, small pipe diameter, Low strength oil and gas pipeline can not meet the requirements of the times. Therefore, high pressure, large diameter and high strength pipeline come into being. In order to ensure the safety of these high steel pipeline in daily operation, In addition to ensuring the quality of the pipeline, the safety state of the welded joints of the pipeline is also very important, because most of the pipeline leakage accidents begin at the weld seam. This paper systematically describes the present situation of the natural gas pipeline at home and abroad. In theory, taking X70 X80 pipeline steel as the carrier, the types and causes of crack defects caused by the change of temperature in the welding process are analyzed. The main reason is that these defects reduce the effective area of the bearing cross section of the structure, and the main reason is that these defects reduce the effective area of the bearing cross section of the structure. At the same time, stress concentration is produced in the area around the defect, which has a negative effect on the service performance and service life of the welded piece. In order to ensure the quality of the welded joint of the pipeline, it is necessary to carry out routine inspection. However, NDT can detect high grade steel pipes in production and operation so as to detect various defects in time and take corresponding measures. In order to reduce the unnecessary loss during the operation of the pipeline. The advantages of reliable data and low cost have become the main means to detect the weld defects of pipeline. In this paper, the digital ultrasonic flaw detector is used to test the self-made simulated samples of natural defects. The effects of probe type, probe parameters (frequency K value, wafer size, coupling agent and scanning mode) on the detection sensitivity in the detection technology of S-wave oblique probe are analyzed and summarized, and how to select the probe is put forward. Only by coupling agent and scanning method can the crack defects in weld seam be detected more accurately. When the indicated length and height of the crack defect and the distance between the crack and the center line of the weld seam are measured, the size of the crack is compared with that of the pre-buried theory. It is found that nearly 90% of the practical data errors are less than 9%, which verifies that ultrasonic inspection is quite accurate and reliable in the detection of weld crack defects in high grade steel pipelines.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE973

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