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文中通过粘弹体防腐胶带与热收缩压敏带复合结构在唐山LNG外输管道工程中的应用,介绍了粘弹体加热收缩压敏带复合补口结构的施工方法和检测方法,对这种补口方法现场出现的问题进行分析解决,并将该补口方法与传统的热收缩套补口方法进行了对比,分析2种补口方法的优缺点,得出了比较结果,提出了对粘弹体结构的建议。 相似文献
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埋地钢质管道熔结环氧粉末外防腐层补口方法比较 总被引:4,自引:1,他引:4
根据“钢质管道熔结环氧粉末外涂层技术标准”SY/T0315-97的规定,现场补口宜采用与管体相同的熔结环氧粉末涂料进行热喷涂。但是,通过现场应用及几次补口招标演示,采用熔结环氧粉末涂料进行热喷涂,补口质量很难达到设计要求。为解决熔结环氧粉末外涂层补口问题,在不同的工程中,又采用了无溶剂液态环氧涂料和热收缩套等补口材料进行现场补口。本文对目前国内采用的埋地钢质管道熔结环氧粉末外防腐层三种补口方法的优缺点及经济因素进行了分析,比较。 相似文献
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针对目前管道建设中应用的几种主要防腐层补口材料的 9种基本性能 ,采用权重系数法进行了优化 ,计算出几种主要防腐层补口材料的s值 ,认为其s值为 0 9以上的补口技术成熟 ,s值小于 0 9的补口材料还需要进一步研究 ;根据优化结果确定了单层FBE、双层FBE、煤焦油瓷漆、三层PE防腐层各自比较适宜的补口材料。单层FBE和双层FBE针对熔结FBE和液体环氧而言 ,补口技术比较成熟 ;煤焦油瓷漆和三层PE防腐层针对热收缩套补口材料而言 ,其补口技术还不成熟 ,有待进一步研究。 相似文献
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文中分析了国内外热收缩带质量差异的原因及后果,介绍了美国瑞侃(Raychem)公司、加拿大卡努沙(Canusa)公司产品实际试用的情况。在技术经济对比的基础上,确定定向钻管段补口应选用进口的定向钻专用热收缩带,顶管段、水下段和大开挖管段补口最好也选择进口的通用热收缩带。 相似文献
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大口径管道防腐层一般采用人工补口方法施工,存在施工效率低、质量缺陷多及受限空间施工安全风险大等问题.文中主要介绍了在钢管内防腐补口施工中采用内补口车替代人工补口的施工技术.设备调试、定位、通过性及质量控制是施工中的技术难点,施工中通过参数调整、视频定位、使用专有的机械设计、合理施加外力及采用过程中监控等技术方案顺利解决... 相似文献
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Pedestrians as compared to vehicular traffic enjoy a high degree freedom of movement even in heavily congested areas. Consequently, there are more alternative links available to pedestrians between a given origin‐destination (O‐D) pair. This paper describes a study done by the University of Calgary to evaluate the factors affecting the choice of route on intra‐CBD trips or trips within the Central Business District (CBD). An origin destination survey conducted in downtown Calgary, Alberta enabled the identification of the most significant factors influencing the choice. These factors were analyzed in relation to the physical characteristics of the location, personal characteristics of the trip maker and the type of the trip. It appears that most people chose the shortest link and factors such as the level of congestion, safety or visual attractions were only secondary. This suggests that the length should be made a major consideration when planning and designing pedestrian links. 相似文献
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本文阐述了混合动力列车的技术特点及其相应优势与劣势,同时介绍了其在国内外的研究动向,并对其应用前景进行了展望。尽管该类新型铁道车辆的续航能力、电池寿命以及成本等相关问题目前仍有待改善,但以其对城市环境的美化作用与优越的舒适驾乘性能,以及高效节能、绿色环保的显著优势,依然不失为一类充满前景的新型轨道交通运输方式。 相似文献
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明确埋地管道防腐保温层的技术评价标准,对埋地钢质管道的安全运行,延长管道使用寿命具有重要意义。为了对埋地管道防腐保温层做出有效评价,从间接检测与开挖检测2个方面,结合现场检测数据,提出了基于防腐保温层的电流衰减率、绝缘电阻率、质量状况与厚度的分级评价标准及基于4种评价指标的综合评判方法。工程实践表明,该评价标准对防腐保温层是否存在失效能做出有效判断。 相似文献
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In India pedestrians usually cross the road at mid-block crosswalks due to ease of access to their destination or the development of adjacent land use types such as shopping, business areas, school and residential areas. The behaviour of pedestrian will change with respect to different land use type and this change in behaviour of pedestrian further reflects change in perceived level of service (LOS). So, it is important to evaluate the quality of service of such crossing facilities with respect to different land-use type under mixed traffic conditions. In this framework, pedestrian perceived LOS were collected with respect to different land-use type such as shopping, residential and business areas. The ordered probit (OP) model was developed by using NLOGIT software package, with number of vehicles encountered, road crossing difficulty as well as safety considered as primary factors along with pedestrian individual factors (gender and age), land-use type and roadway geometry. From the model results, it has been concluded that perceived safety, crossing difficulty, land-use condition, number of vehicles encountered, median width and number of lanes have significant effect on pedestrian perceived LOS at unprotected (un-signalized) mid-block crosswalks in mixed traffic scenario. The inferences of these results highlights the importance of land use planning in designing a new set of pedestrian access facilities for unprotected mid-block crosswalks under mixed traffic conditions. Also the study results would be useful for evaluating pedestrian accessibility taking into account different land-use type and planning required degree of segregation with vehicular movement at unprotected mid-block crosswalk locations. 相似文献
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This paper estimates the efficiencies and productivity changes of 12 international airports in the Asia-Pacific region based on data from 1998 to 2006. We apply stochastic frontier analysis (SFA) to compute efficiency estimates and use the Malmquist productivity index (MPI) to analyze productivity changes. We use the SFA model with a translog-type production function after testing the statistical hypotheses. According to the results of the SFA hypothesis tests, airports have experienced a technological regression; the deviations from the efficiency frontier are caused more by technical inefficiency than random noise. However, the inefficiency was found to decrease. The MPI reveals a declining trend resulting more from technological change than from efficiency change, with a decrease in inefficiency. Taken together, both the hypothesis tests and the MPI not only provide consistent conclusions, but also suggest that airports should concentrate on technological progress. 相似文献