聚乙烯管材的连接方法和技术

为充分发挥聚乙烯（PE）管材的先进性，经济性和安全性，对PE管材的各种连接方法进行了广泛的研究。介绍了PE管材的热熔对接焊，电热熔焊，热熔承插焊，鞍形/侧壁熔焊，以及钢塑过渡接头连接方法和技术，并对热熔对接焊和电热熔焊作了较深入的探讨，同时进一步分析了不同塑料管材间的焊接方法。     

聚乙烯电熔接头管材熔融区深度与焊接性能关系研究

在聚乙烯管道电熔焊接过程中,形成接头强度主要取决于套筒和管材界面聚乙烯高分子链的扩散缠结阶段经历的时间,该时间与熔焊区扩展到管材内部的熔融区深度存在一定的对应关系。为探索聚乙烯电熔接头管材熔融区深度与接头焊接性能的关系,提出了一种管材熔融区深度的超声测量方法,开展了管材熔融区深度测量和焊接性能试验。结果表明,管材熔融区深度与界面焊接强度有明确的关联,管材熔融区深度在一定范围内时,就能保证基本的剥离强度值和界面韧性;在此基础上提出一种以管材熔融区深度确定电熔接头焊接时间的新方法,该方法充分考虑到环境温度、焊接电压、电阻丝电阻等各种偏差,更能适应实际工程。     

新型结构蒸发器的制造

蒸发器管程为蛇形加热管线。管束是蒸发器的核心部件 ,制造管束的关键是控制异径管以及异径管与封头管板的焊接质量。加热管线通过异径管的套管与封头管板相连接。异径管的套管与管板的连接是挠性结构 ,改善了连接点的应力状况 ;U形管的中心距和管板、支持板的中心距必须保持一致。加热管的对接焊缝必须进行 10 0 %射线探伤。由于管孔和U形弯头的中心距较小 ,异径管与封头之间的空间有限 ,为方便换热管与异径管、封头管板与异径管的焊接 ,采取从上到下 ,按排组焊、无损探伤的组装方法     

城市燃气管网应用ERW钢管及其防腐问题

从天然气改变能源结构的重要意义上，探讨了天然气同人工煤制气在管网输配上的区别，并论述了高频直缝电阻焊钢管（ERW）先进的生产工艺，几何和物理无缝化特点，同时对铸铁管，高密度聚乙烯9HDPE）管，无缝管进行了性能和造价的综合比较。根据设计规范，而得出ERW钢管是城市燃气管网的首选管材，对埋地钢管外防腐层的选用问题，也进行了国内外应用技术和理论的探讨。     

Interpretation of results of full notch creep test and comparison with notched pipe test

Abstract

An investigation of two tests commonly used to determine resistance to slow crack growth in PE pipes and materials is detailed, in order to gain a greater understanding of the mechanisms involved and to resolve differences in results observed. The full notch creep test (FNCT) is carried out on small notched bars machined from sheet or pipe loaded to create high constraint at the notch tip. The notched pipe test (NPT) is a pressure test on pipe containing external machined notches. In this test, it has been observed that the use of more flexible materials allows deformation in the crack tip region and contributes to slow crack growth resistance via crack tip blunting. Good pipe performance can be achieved by selecting materials with high inherent slow crack growth resistance or by combining inherent resistance with blunting mechanisms promoted by a lower density material. It is concluded that the FNCT test, while useful for an indication of inherent slow crack growth resistance, cannot be used to predict pipe performance for a range of materials, and therefore is unsuitable as a reference test for a pipe product specification. The NPT test remains the benchmark test for pipe performance and is referenced by many specifications.     

Optimization of process parameters for rehabilitation of pipes through adhesive bonding: experimental study

Abstract

In many industries maintenance and repairing of pipes are crucial elements to engineers. The processes may consume a lot of money and time. Conventional methods like welding, riveting etc. may damage the base material or some times the pipe may carry inflammable fluids which can not be possible to repair by conventional methods. In such a case, adhesive bond may provide an alternative solution to the pipe repair or strengthening applications. The present work focuses on the optimization of process parameters which enhances the adhesive bond capacity (Tensile shear load) between carbon fiber reinforced polymer (CFRP) composite patch and SS (SS 304) plates. Epoxy resin and adhesive combination, pre cure temperature and surface preparation was considered as parameters. The surface roughness of pre-bond surfaces was measured using a 3D-microscope. The quality of the adhesive bond was evaluated using non-destructive testing (Digital Radiography) before performing tensile test. The failed surface morphology was studied using FE-SEM images. The optimal parameters were derived form the tensile test data of the adhesive joint. The bond capacity for lateral loadings was also studied using a three point bending test at the derived conditions. These parameters were also applied to rehabilitate the damaged pipe and its ability was evaluated through hydrostatic pressure test. From the results, it was observed that these parameters hold good for pipe rehabilitation also.     

尿素合成塔物料管管口裂纹统计与成因初探

对水溶液全循环法尿素合成塔物料管检验缺陷进行了统计分析,指出物料管缺陷主要是液氨物料管管口裂纹,其是由物料管焊接结构、温差应力、腐蚀介质和工况条件等因素综合影响造成的。并指出可以通过控制工艺稳定性,采取预混甲液和液氨以及改善焊接接头应力集中程度等方法来降低液氨进口管管口裂纹出现的频率。     

工程塑料管道焊接质量检测和性能评定方法

随着工程塑料管道应用的不断深入,管道的焊接质量检测及其性能评定成了一个重要的问题。介绍了工程塑料管道焊接接头的外观检测、内部缺陷的无损检测、焊接接头性能试验及快速裂纹扩展和慢速裂纹扩展方法等,这些对推动工程塑料管道的广泛使用具有重要的意义。     

Investigation of the stress and strain state of clay pipes under fire condition

The focus of this paper is given to investigating the testing and evaluation method of stress and deformation behaviour of clay pipe elements like chimneys under cyclic high temperature. The experimental study on the temperature–time curves and on the radial deformation–temperature curves of a series of fire-resistant clay pipes was carried out. The tensile strength and the compressive strength, the elastic modulus before and after fire, the stress and deformation properties and the cracking behaviour of the clay pipes under fire conditions have been analyzed. The theoretical analysis corresponds well with the experimental results and tends to prove that the elastic deformation can be the most significant component in fixed-end clay pipes. This study is useful for evaluation of the stress–strain properties of ceramic pipes and provides a beneficial test method for the pipe member in small-scale or in full-scale tests under fire temperatures.     

BGL气化炉接管局部烧损修复方案可行性分析

BGL气化炉鼓风口的接管局部烧损,此鼓风口接管为20 MnMoⅢ锻造接管.为尽快修复设备,制定了利用现有材料16 MnⅢ锻造接管进行局部焊接补齐的修复方案,但此16 MnⅢ锻造接管厚度低于原接管厚度.为确保方案的可行性,从修复方案的强度核算及焊接工艺两方面进行了分析论证,证明上述修复方案可以实施.     

一步法硅烷交联聚乙烯铝塑复合管生产技术

一步法硅烷交联聚乙烯管材加工技术应用于铝塑复合管成型加工,是将薄壁金属管高速焊接和聚合物反应挤出成型这两个跨专业的新技术有机地结合为一体,从而建立起一种加工新型管材的新兴工业技术。铝塑复合管内外聚合物层采用一步法硅烷化学交联聚乙烯反应挤出技术加工内管和外管,比采用两步法交联技术节省40%以上原材料,并有利于生产组织。薄壁金属管焊接采用高频束流钨板惰性气体保护焊(TIG)技术,最高生产速度可达20m/min,整条生产线由三台牵引机、四台挤出机、二台TIG焊机、二台助剂计量泵及高频感应加热装置等构成。     

气液分离器焊接接头裂纹原因分析及修复

对煤气化装置气液分离器高强度钢与异种钢小型接管之间在焊接过程中连续出现的焊接接头裂纹进行分析,通过采用正确的焊接材料,制订切实可行的维修方案,焊接一次成功,焊后检测未发现焊接缺陷。     

化工厂地下水管裂漏快速永久性修复

本文简要介绍化工厂地下环形供水管网裂漏，在裂漏点前后阀门关闭不严。阀门以外管网又需保证正常供水压力的情况下而进行的快速永久性修复。     

双相不锈钢复合钢板压力容器加工工艺

文章从双相不锈钢复合钢板一级分离器的制造问题入手,制定了设备的工艺方案,并通过详细的方案拟定接管法兰的焊接加工工艺,从保证焊接质量、节约制造成本及简化工艺流程的角度分析并选择适合工艺方案。     

非金属管道的受力分析与结构设计

针对顺北油田苛刻的腐蚀环境和特殊的地形地貌，地面集输管线建设面临沙丘起伏大（落差>10 m）、移动性强（沙暴天气>1个月）等不利因素，开展非金属材料管体和接头的受力分析和结构设计研究。利用有限元分析软件对不同内径的管材在不同外压载荷作用下展开的分析，计算管材在不同载荷下对管材挠度与应力的影响，校对所设计的结构是否能达到使用标准。结果表明，在内压载荷下增强层是主要承压层，增强层损坏意味着管道的失效；外压载荷下的风力载荷对管道影响最小，惯性载荷与沙丘移动均对悬空管道产生较大影响，可以通过应力分析来判断管道连接的可行性。     

新型悬挂式管板焊机机头研制

悬挂式管板焊机在大直径换热器的制造和维修上具有很大优势．但目前国产悬挂式焊机技术与国外相比还有一定差距。为解决焊机机头悬挂使用条件下焊枪精确定位与调整、机头轻量化等技术难题,开发了一种新型悬挂式管板焊机。该焊机采用胀管器胀管定位方式以及新型的焊枪轴向、径向调整结构,具有结构紧凑、功能完善、工作可靠和焊接质量好等特点。该焊机机头已经产品化并规范应用。     

双轴取向聚氯乙烯管材解取向研究

将双轴取向聚氯乙烯（PVC-O）管段进行加热，使其发生2种不同程度的解取向：完全解取向、轴向解取向。通过对PVC-O成品管段、完全解取向管段、轴向解取向管段、坯管进行低温抗冲试验，另对PVC-O成品管段和轴向解取向管段进行轴向拉伸和径向拉伸试验，分析解取向前后管材的力学性能。结果表明，完全解取向管材的低温抗冲性能和轴向拉伸性能会降低；轴向解取向管材的低温抗冲性能和轴向抗拉性能降低，径向拉伸性能变化不大。     

热管科学及吸液芯研究进展回顾与展望

首先回顾了热管基本工作原理,随后分别简述了热管发展过程中衍生的热虹吸管、往复热管、脉动热管、回路热管、旋转热管、微型热管和可变导热管.列举了它们在提高铁路路基可靠性、延长机械零件寿命、强化集成电路散热和提高温度测量精度等方面的应用.着重阐述了热管核心吸液芯结构以及复合吸液芯的发展带来的渗透率和毛细力的提高.热管材料的相容性制约热管的使用寿命,相容性材料的选择亦是热管设计的重要内容.最后简述了热管传统加工制造方法,即管壳与吸液芯分开加工的方法.热管微型化发展和与服务对象的结合对热管形状和吸液芯结构多元化的要求不断提高.提出了基于三维打印的新型热管加工方法,此方法便于热管管体与吸液芯结构一次成型,并直接将管体与被散热体集成一体,从而达到以往难以实现的复杂散热效果和经济效益.三维打印技术的飞速发展有望为吸液芯结构的创新提供新的空间,同时为热管的应用提供一个更为广阔的市场.     

The essential work of fracture characterization of PVC pipes and its correlation to the degree of gelation

PVC pipes (ABNT NBR 5647) were characterized by its essential work of fracture (EWF), using test specimens prepared from flattened sections and directly from rings cut from the pipes. These pipe samples were also characterized for the degree of processing by immersion in dichloromethane and differential scanning calorimetry (DSC). The results obtained for the essential work of fracture show statistically identical values, independently of the type of test specimen, demonstrating that this test can be carried out directly on test specimens prepared from pipe rings, without changes in their actual state of processing. The evaluation of the processing quality through immersion in dichloromethane does not apply to ABNT NBR 5647 pipes, since the results show that, despite the strong attack after immersion, the pipes are well processed, taking into account these new evaluation parameters. J. VINYL ADDIT. TECHNOL., 25:3–8, 2019. © 2018 Society of Plastics Engineers     

PE管电熔焊接和热熔焊接在施工中的比较

目前,塑料管道在中国正在稳步发展,PE管、PP-R管、UPVC管都占有一席之地,其中PE管强劲的发展势头最为令人瞩目。PE管的使用领域广泛。其中燃气管和给水管是其两个最大的应用市场。PE管作为煤层气输送管线在施工中得到普遍的应用,根据以往施工实践的总结,对于PE管的热熔和电熔两种比较成熟的施工方法进行分析和比较。