Assessment of welding defects for gas pipeline radiographs using computer vision

In this paper, a novel automated vision system is introduced to detect and assess the welding defects of gas pipelines from the radiographic films. The proposed vision system was used to capture images for the radiographic films and apply various image processing and computer vision algorithms to detect the welding defects and to calculate necessary information such as length, width, area and perimeter of the defects. A developed software, named AutoWDA, has been fully written in lab using Microsoft Visual C++6 to perform the analysis process. The proposed system offers many advantages such as enhancing the captured images so that the defects appear much clear and eliminating the loss of image details, which occurs due to film deterioration by the time, by transferring the radiographic films into digitized images, which could be saved on magnetic mass storage media. The proposed system is considered quite cheap compared with commercial radiographic image enhancement systems.     

国内外长输管道对接焊缝射线检测验收标准比较分析

对长输管道射线检测评定标准SY4056－1993《石油天然气钢管质道对接环缝射线照相和质量分级》和API1104《管道及有关设备的焊接》作了比较分析，两个标准在焊缝质量的缺陷评定上有一定的差别，在具体应用中，应根据两个标准的各自特点进行综合考虑。     

下向焊大口径管对接接头焊接缺陷分析

为提高下向焊大口径管的焊接质量,针对下向焊大口径管的焊接工艺特点,选择适当的射线透照工艺和技术参数,对下向焊大口径管对接焊缝进行100％X射线探伤。通过所拍x光底片,分析焊接时生成缺陷的类型、位置以及产生原因。     

建筑钢结构梁、柱焊缝的手工超声波探伤

钢梁、柱是建筑钢结构系统的主要部件,其焊接工艺、焊缝类型和坡口状况决定了容易出现的缺陷类型。分析和整理了钢梁、柱焊缝探伤方法以及探伤标准。详细介绍了梁、柱焊缝手工超声波探伤的技术条件、检验方法和缺陷辨别等探伤程序。     

Automated detection of welding defects in pipelines from radiographic images DWDI

This paper presents a method for the automatic detection and classification of defects in radiographic images of welded joints obtained by exposure technique of double wall double image (DWDI). The proposed method locates the weld bead on the DWDI radiographic images, segments discontinuities (potential defects) in the detected weld bead and extracts features of these discontinuities. These features are used in a feed-forward multilayer perceptron (MLP) with backpropagation learning algorithm to classify descontinuities in “defect and no-defect”. The classifier reached an accuracy of 88.6% and a F-score of 87.5% for the test data. A comparison of the results with the earlier studies using SWSI and DWSI radiographic images indicates that the proposed method is promising. This work contributes towards the improvement of the automatic detection of welding defects in DWDI radiographic image which results can be used by weld inspectors as a support in the preparation of technical reports.     

Energy characteristics of the power source‐welding arc system

Analytical decisions supported by experimental data were used to determine the dependences for calculating the size of the heat-affected zone (HAZ) in multilayer welding of circumferential joints in transmission gas pipelines. Data on the dimensions of this zone are essential for evaluating the possibility of applying cold cutting in the rejection of elements of gas pipelines because of defects in circumferential welded joints or welded joints in transition rings in the vicinity of circumferential welded joints.     

弧焊离线编程系统中计算机辅助编程技术

从为实现离线编程系统中计算机自动编程目标出发,对焊接工件特征建模、焊接参数规划技术进行了研究.研究了综合特征识别、特征定义与特征设计的焊接工件特征建模技术,并在SolidWorks之上开发了焊接工件特征建模器.采用基于事例推理和人工神经网络等人工智能技术,开发了用于机器人弧焊的焊接参数过程规划器.     

焊接缺陷对聚乙烯管道焊接接头强度的影响

聚乙烯燃气管道由于其耐腐蚀、柔性好、施工效率高等优良特性,已逐渐在城镇燃气运输中取代钢制管道,成为主要的输送方式。聚乙烯管道的安装主要采用电熔和热熔焊接方式,存在的主要焊接缺陷有过焊、冷焊、氧化皮未去除、电阻丝错位、孔洞等,文中研究了不同焊接缺陷对聚乙烯焊接接头强度的影响程度及影响机理。采用拉伸、压扁、SEM和EDS测试方法对带有人为缺陷的焊接接头进行分析测试。拉伸、压扁力学性能结果表明,影响聚乙烯管道焊接接头强度的主要缺陷为冷焊、过焊、氧化皮未去除、电阻丝错位,其中氧化皮未去除对接头强度的影响最大,为正常焊接断裂应力的0.4%;SEM和EDS测试结果表明,含有氧化皮的管材分子链易交联、断链,流动性差,热氧老化的硬质斑块和机械划伤阻碍了聚乙烯母材大分子链的扩散,同时在紫外线、光、热等作用下,氧与聚乙烯表面分子链发生反应,形成大量羟基自由基团,使得聚乙烯分子链发生热氧老化和降解,大大降低了聚乙烯接头强度。     

5052铝合金交流脉冲等离子弧焊接工艺

采用交流等离子焊接方法,使用焊材ER5356对8 mm 5052铝合金进行了等离子弧立向上焊接试验。通过合理的设计焊接工艺和严格控制焊接关键因素,解决了5052铝合金焊接性的问题。结果表明,交流等离子弧焊接方法适用于5052铝合金的焊接,根据标准对焊接接头进行力学性能检测、X射线检测与焊接接头金相分析。结果表明,焊接接头弯曲和拉伸性能符合检测标准要求,冲击吸收能量在15℃条件下均大于19 J;焊缝无气孔、夹渣等缺陷,焊缝中组织基体为α(Al)固溶体。     

Principles for the evaluation of gas cavities in welded joints of steel on the basis of radiographs according to different European standards

During making a weld, many metallurgical reactions resulting from interaction between slag, gas and metal take place. These reactions influence the quality of welded joints. The oxidation, nitriding and hydriding phenomena occurring in welding processes can be a reason for gas void formation. Gas voids, which are the internal imperfections, are detected most often by radiographic methods. The purpose of this paper is to present the principles of assessment of gas cavities in welded joints, specified in different acceptance standards, on the basis of radiographic examination.     

焊缝射线检测图像的缺陷搜寻与算法优化

基于X射线成像的焊缝缺陷自动检测技术对提高工业射线检测的自动化水平具有重要意义。在通过图像处理算法进行焊接缺陷提取的过程中,存在各种干扰,要求算法有很强的抗干扰能力。尝试了均值滤波背景相减和底帽变换两种缺陷提取算法,并分析存在的主要问题。针对这些问题,提出相应的解决办法,即模板优化算法和多特征再筛选算法,有效地解决了缺陷误检和漏检之间的矛盾。     

Potential risk of propagation of defects and welded joints in pipelines in hydrogen sulphide-containing fields

The main reasons for failure of welded joints in pipelines in hydrogen sulphide-containing oil and gas fields are discussed. A method is proposed for evaluating the potential risk of non-crack defects in the circumferential welded joints, based on the results of full-scale tests of pipes and theoretical calculations. The method can be used to determine the permissible working pressure and justify the further service of sections of pipelines containing defective welded joints.     

超纯铁素体Cr30Mo2钢焊接接头的组织和力学性能

利用自制的焊接工作台,在ＴＩＧ焊基础上,对Ｃｅ３０Ｍｏ２超纯铁素体不锈施焊。焊接中对焊缝和热影响区附加拖罩和背;衬的Ａｒ气延续保护。对焊接接头质量进行宏观坶检验;借助金相显微镜、扫描电镜（ＳＥＭ）、透射电镜（ＴＥＭ）分析焊缝组织特征一冲击断口形貌;按国家标准测试焊接接头的力学性能。华发头上未发现任何焊接缺陷,焊接缝质量良好;其强度、延性和韧性均达到母材水平,特别是在焊缝和热影响区未出现脆化现象,冲     

Influence of interpass temperature on the properties of duplex stainless steel during welding by submerged arc welding process

Duplex stainless steels are materials that present high corrosion resistance with high values of mechanical strength, therefore motivating their use in various components in the offshore industry. However, there are major challenges in the welding of these materials in terms of the productivity and quality of the joint produced, considering its extensive use for components of small thickness, such as umbilicals, to those of large thickness, such as salt water injection pipelines. In relation to pipes of small thickness, the gas tungsten arc welding process is successfully used. In thick-walled pipes, the automatic process of submerged arc welding (SAW) has been recently implemented in lines of pre-assembled piping, and this has considerably increased the productivity of the joints produced, though, a great deal of time is required to perform a new weld pass, due to the fact that the maximum interpass temperature needs to be lower than 150 °C. This work presents the results of characterization and the evaluation of corrosion resistance of a welded joint corresponding to DSS UNS S31803, with a wall thickness of 21.4 mm, welded by the gas metal arc welding process in the root and SAW process in the filling and cap passes, employing an interpass temperature between 150 and 290 °C. The results of the characterization of the mechanical properties, chemical composition and corrosion resistance in different regions of the welded joint were compared with those obtained for the base metal of the pipe, as well as with the minimum values required by the project standards. Therefore, this study has made an evaluation of the influence of the interpass temperature in the properties of the joints produced, motivated by a possible increase in productivity in pipe welding.     

运行管道在线焊接时的氢致开裂与防止方法

油气输送管道于腐蚀或机械损伤引起的减薄区以及由于管道的大段破坏或工艺要求需要安装分输支管、通常要进行现场妆操作。该操作如果在不停输的情况下进行,会大大减少由此引起民的经济损失。但是在不停输情况下焊接,由于管内介质的流动而产生的快冷效果可能会形成热影响区（ＨＡＺ）的氢致开裂。为了避免氢致开裂获得优良的焊接接头。本文 碳钢管的循环试验管道上初步研究了焊接残应力、焊接区冷却速度、焊接工艺条件等因素对运行     

Effect of welding technology on the mechanical properties of welded joints in pipes for deep water offshore gas pipelines

Results of investigations into the dependence of mechanical properties of welded joints of pipes for offshore pipelines on welding conditions are presented. In particular, the results show that the mechanical properties of pipes of the strength categories K60 (X70) and K56 (X65) are influenced mainly by the heat input, the fracture toughness of welded joints, and pipes of a high strength category are lower by 30–35% than in the case of the K56 (X65) pipes. The hardness of the weld metal in the upper layers is 15–17% higher for automatic submerged arc welding and in the lower layers for gas-shielded automatic arc welding. In inspecting the mechanical properties of the welded joints, special attention must be given to the longitudinal welded joints in the pipes.     

中海拔地区钢轨焊接工艺及质量对比

以包钢U75V热处理钢轨焊接为对象,依据焊接接头型式检验结果,对比研究兰州铁路局中海拔地区基地闪光焊、现场移动式闪光焊、移动式气压焊及铝热焊接头性能。结果表明:基地焊接接头综合性能最佳,现场移动式闪光焊和移动式气压焊接头综合性能相近,铝热焊接头性能最差。     

特高压开关铝罐体的变极性等离子弧焊接工艺方法

通过对16 mm厚5083铝合金罐体进行变极性等离子弧焊接工艺试验,分析了工艺参数变化对焊缝成形的影响,研究该铝合金罐体在不开坡口情况下分别采用氩气(需要焊前预热)和氦氩混合气作为保护气的变极性等离子弧焊接工艺,并制定出具体焊接工艺规范参数。试验结果表明,采用氦氩混合气作为保护气条件下焊接的工件,可以有效避免长焊缝预热不均、焊缝背面局部咬边等问题,同时可以降低热输入、提高焊接效率,焊缝质量达到正背面外观无缺陷、射线探伤Ⅰ级,能够满足高压开关罐体的设计要求。     

射线照相黑度值的重要性及其标准规定值的合理性

黑度是射线照相检验中的一个重要参数，我国射线照相标准中的黑度规定值与国际标准化组织（ISO）和国外标准存在的较大差距。指出该参数与景仰质量和检测有效性、可靠性的利害关系，建议按两种主要焊接接头型式分别规定射线照相许用黑度范围。