【作者】 李晨光；

【导师】 陈国明； 李安；

【作者基本信息】 中国石油大学 ， 安全技术及工程， 2011， 硕士

【摘要】 天然气是21世纪主要的能源之一,干线输气管道是连接矿场集气系统和城市门站的纽带,是一个复杂的动力系统,管道绝大部分埋于地下,运送量大,占地少,受地形和气侯影响小,是目前最有效、最大规模的运输系统。市场经济决定了要建设长输管线,以获得最大的经济利益和社会利益。但是天然气并不等同于一般的油品,天然气管线主要承担的任务还是向许多居民供气,涉及千家万户的日常生活和社会稳定。天然气管线输送压力高,介质易燃易爆,管道的损伤会导致爆裂或撕裂,难以短期修复,因此要求管道要有好的质量,焊接过程中要防止产生裂纹等缺陷,整个施工过程要求精细作业,并建立完善的输气管道质量保证体系。随着新能源工业的迅猛发展,国内外的许多长输管线将建成并投入运营,管道的安全性和可靠性将是对管线建设和管线集输最基本的要求。焊接技术作为长输管线施工的关键技术,直接关系到工程质量、施工效率、施工成本以及管线运行期间的安全可靠性和经济效益。天然气管线由于高温高压及管线所在地区的复杂性,极易发生破裂、失效和泄漏,所以安全输送已经成为涉及社会和消费者重大利益的问题,一旦发生事故,会给企业和国家造成重大的损失和巨大的负面影响,因此无论对管线的现场焊接,还是对焊接人员和管理人员都提出了更高的要求,迫切需要对焊接质量控制做出全面而科学的规定。本文还对激光焊接技术的基本理论和优缺点进行了描述,同时根据目前激光焊接技术的发展及趋势,对厚壁管的激光焊接问题做了初步的探讨。焊接结构的缺陷检测评价是一项关键工序,焊接结构检测技术在不断发展完善。随着信息技术的日新月异,常规检测方法有了更多的突破和创新,新的检测技术和方法层出不穷,例如射线检测实时成像技术、TOFD技术、太赫兹无损检测和红外热成像检测等新的检测技术得到了长足的发展和应用。对焊接及其它工业生产活动的质量保证起到了重要的保障作用。本文详细描述了焊缝成形的过程,缺陷的种类以及产生的原因和后果,说明了焊缝缺陷对管材的各种疲劳损伤和断裂的作用,明确了管道焊缝无损检测的重要性。重点研究了TOFD技术和红外热成像探测技术,表明它们以其原理简单,操作方便,对管道环形焊缝内缺陷的高检出率而有广阔的应用前景。较高的缺陷检出率有助于无损检测人员及时做出评价,决定是否进行修复,而且还可以根据所得到的缺陷情况和焊接的质量预测管道运行的质量和服役的寿命。数字图像在各行业有着十分广泛的应用,图像处理及图像理解在工业检测、工业探伤,计算机辅助生产等方面起着加快生产速度、保证质量的作用。本文重点介绍了智能图像处理和光电图像处理的内容,尤其在红外焊缝图像的处理与应用方面做了大量的探讨,在多种无损检测方法的综合使用中,针对焊缝红外图像的特点和特征,尽可能使用合理的方法分离出焊缝缺陷,提高焊缝缺陷检出率,保证管道焊接的高质量。更多还原

【Abstract】 Natural gas is the one of major energy sources in 21st century. The trunkline is a complicated power system that is buried under the ground with gigantic transportation volume, less field areas, less impact by terrain and climate, linking field gas-collecting system and city gate stations, is considered as the most effective and the largest scales delivering system at present. The long distance of natural gas pipeline is determined by market economy for achieving maximum economic profits and social interests. Nevertheless, the natural gas is not identical to ordinary product oil, because the natural gas pipeline is to provide the residents with fuel, related to everyday life of families and social stability. With flammable combustible gas, the trunkline of natural gas is featured with high transporting pressure, vulnerable to crack and tear-down due to damage. The sabotaged pipeline can not be repaired in very short time so that the defects such as crack shall be prevented for better quality which requires meticulous operation during the construction and establishment of impeccable quality-assuring system for pipeline.As fast development of new energy industry, a good number of long-distance pipelines at home and broad will be put into service based on the primary safety and reliability to be required by pipeline construction and storage & transportation. The welding technology in close connection with quality of project, efficiency, cost, safety, reliability and profits, has been working as key part of construction. Susceptible to fracture, failure and leakage, the gas pipeline has become significant issue on society and end users in terms of safety, because any accident will bring about great losses and negative influence. The higher requirement will be proposed for field welding service and working staff in urgent hope of comprehensive and scientific standard for welding quality control. In addition, the thesis describes rudimentary theory and relative merits of laser welding technology. In the meanwhile, the preliminary probe is done to laser welding on thick wall pipeline according to progress and tendency of laser welding.Detection & evaluation of welding structure for potential defection is a key procedure shaped continuously. With the updating of information technology, regular detecting methods have had more breakthrough and creation, such as TOFD, THz NDT and infrared imaging NDT, which safeguard the welding quality and other industrial activities.The paper detailed the process of forming of weld beads, types of defects and reasons and consequences to be occurred, describing fatigues and damages by the mentioned defects and importance of NDT of pipeline welding beads. The key attention has paid to TOFD and infrared NDT technology for manifesting high successful findings and expansive prospect due to simplicity and amenity. The high successful finds will help NDT staff with prompt assessment and decision for repairing, moreover, with predict running of pipeline and life span of service according to statement of defects and welding quality.Digital image technology has found their versatile roles in many fields. Image processing and image understanding speed up production and guarantee quality in industrial testing, industrial detecting, CAM etc. The paper has introduced a large number of intelligent imaging and photoelectric imaging contents, particularly had discussion in terms of infrared bead image processing and application. In the synthetic application of multiple NDT technology, the most reasonable method has been applied to separate defects from images of the beads on the basis of characteristics of infrared images for increasing successful rates and make sure high quality of pipeline welding.更多还原