Metal Sealing Performance of Subsea X-tree Wellhead Connector Sealer

The metal sealing performance of subsea X-tree wellhead connectors is crucial for the safety and reliability of subsea X-trees. In order to establish the theoretical relation between metal sealing ring＇s contact stress and its structural parameters and working pressure, a mechanical analysis method for double-cone sealing of high pressure vessels is applied in analyzing the metal sealing ring under the condition of preload and operation. As a result, the formula of the unit sealing load for the metal sealing ring under operation with residual preload is shown in this paper, which ensures that the metal sealing ring has an excellent sealing effect and can prevent the metal sealing ring from yielding. Besides, while analyzing the sealing process of the metal sealing ring, the change rule of contact stress and working pressure is concluded here, putting forward that the structural parameters of the metal sealing ring are the major factors affecting the change rule. Finally, the analytical solution through theoretical analysis is compared with the simulation result through finite element analysis in a force feedback experiment, and both are consistent with each other, which fully verifies for the design and calculation theory on metal sealing ring＇s contact stress and its structural parameters and working pressure deduced in this paper. The proposed research will be treated as an applicable theory guiding the design of metal seal for subsea X-tree wellhead connectors.

Stress and thickness calculation of a bolted flat cover with double metal sealing rings

The design of a bolted flat cover is extremely important for the structural integrity of pressure vessels.The present design codes provide the thickness calculation equations for a bolted flat cover with single metal gasket.However,the rules for a bolted flat cover with double metal sealing rings are not developed to date.In the study,a new thickness calculation equation for the bolted flat cover with double metal sealing rings is proposed.First,the theoretical stress solution for bolted flat cover with the double metal sealing rings is obtained,based on the theory of simply supported circular plate and then verified using the results from finite element analyses.The results indicate that the influence of double metal sealing ring on the stress of the flat cover is more serious compared to single metal gasket.Second,a more accurate and reasonable equation is proposed to calculate the thickness of bolted flat cover with double metal sealing rings based on the derived theoretical equations of maximum stress.Finally,the influence of linear load and the spacing between rings on the thickness are discussed.Subsequently,a few suggestions are provided to design low-pressure or atmosphere pressure vessels.The study provides a theoretical foundation to develop design codes of pressure vessels in nuclear reactors.

Rare Earth Application in Sealing Anodized Al-Based Metal Matrix Composites

A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves. The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for A16061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.

Study on Thermal Expansion Coefficient of Sealing Materials for Ceramic Metal Halide Lamps

With Al2O3, Dy2O3, and SiO2 as starting materials, the basic glass of Al2O3-Dy2O3-SiO2 system was prepared by conventional melting technology, and their thermal expansion coefficients （TECs） at different anneal time were investigated. TECs of the basic glass, which were heat-treated under different temperature, were also investigated. The result showed that TECs of the basic glass gradually approached a fixed value as the anneal time was extended, which suggested that most of the inner stress had been eliminated. After heat treatment, the contents of Dy2O3, Dy2Si2O7, and a new crystal increased up to 1200 ℃ and decreased below 1250 ℃, which was consistent with the TEC change of crystallized samples. This suggests that the crystal has a direct effect on TECs of the crystallized samples.

具有圆度误差的径向金属密封接触应力研究

由于加工圆度误差的影响,井下流量控制阀径向金属密封接触应力分布不均匀,从而影响密封性能。利用有限元方法研究具有圆度误差的径向金属密封唇部接触应力分布,并分析圆度误差对径向金属密封接触应力的影响;基于有限元分析结果提出径向金属密封接触应力分布的理论解析式,并进行误差分析。具有圆度误差的径向金属密封唇部接触应力分布的理论解与数值解相符,各参数引起的最大接触应力的平均相对误差约为10%。根据具有圆度误差的径向金属密封副接触应力的分布规律,提出合理的过盈量函数,修正了径向金属密封轴对称结构的悬臂梁模型的接触应力理论关系式,得出了圆度误差下的径向金属密封接触应力分布规律。研究结果为井下流量控制阀径向金属密封的设计提供了理论指导。

铋酸盐封接玻璃的研究及其连接应用现状

无铅低温封接玻璃由于具有绿色安全、成本低、封接温度低等优势,被广泛应用于航空航天、电真空、集成电路等领域。在磷酸盐、钒酸盐、硼酸盐和铋酸盐等多种封接玻璃体系中,因铋与铅具有相似的性质特点,使得铋酸盐玻璃成为最有可能替代铅酸盐玻璃的绿色玻璃钎料。综述了铋酸盐玻璃的成分和性能调控、网络结构的研究现状,介绍了目前使用铋酸盐封接玻璃进行金属、陶瓷同质/异质材料连接的研究进展,最后对未来的发展趋势进行了展望。

芯轴式封隔器金属密封设计及密封性能分析

针对油页岩、页岩油、重质油和富油煤等非常规油气资源采用地下原位改质技术开采,井下存在高温、高压和腐蚀环境,常规封隔器及其密封不能满足工程要求的问题,设计了一种芯轴式金属对金属密封的井下封隔器,密封副采用耐高温和腐蚀的Inconel 625材料,其中密封座采用金属陶瓷涂层结构。进行了封隔器坐封密封原理试验。试验结果表明,封隔器能在油套大环空间隙形成密封,且密封能力随着坐封载荷的增加而增大。基于密封接触能原理,应用ANSYS软件模拟了井下封隔器的密封性能,并对其影响因素进行研究。研究结果表明:涂层厚度和涂层弹性模量对密封能力影响不显著;芯轴密封面椭圆率和过盈量对密封能力影响较大,起决定性作用。基于密封副高温、持久载荷作用下许用应力低和密封能力评价指标,给出了密封结构参数设计方案,密封座涂层材料为Cr_(3)C_(2)-NiCr,涂层弹性模量250 GPa,涂层厚度为0.3 mm,椭圆率为,过盈量为0.02 mm。研究结果可为高温、高压、腐蚀环境下封隔器的开发和应用提供理论指导。

Contact performance analysis of pressure controller's sealing interface in deep in-situ pressure-preserved coring system

The sealing performance of contact interfaces plays the most important role in the design and operation of the in-situ pressure-preserved coring system.To meet the demand of ultra-high pressure-retained coring for oil and gas exploration in deep reservoirs,a quantitative analysis of the contact mechanical behavior of the pressure controller was performed.Based on the micro-contact theory of rough surfaces,a three-dimensional numerical model of the rough contact interface between the valve cover and the valve seat was constructed,and the micro-contact behavior of the metal contact surfaces was comprehensively studied.The results show that the actual contact area of the valve interface increases with the increase of surface roughness before the critical contact point,but decreases after that.Compared with the real contact model with double rough surfaces,although the simplified hard-contact model with a single rough surface can reflect the micro-contact behavior of the rough surface to a certain extent,it cannot truly reveal the microchannel morphology between the sealing interfaces under pressure.Therefore,the realistic double-rough-surface model should be recommended to evaluate the sealing performance of coring tools,particularly for high pressure conditions.The material properties of valves have a significant effect on the contact characteristics of rough surfaces,which suggested that the actual contact area decreases with the increase of the elastic modulus of the contact material under the same loading conditions.The knowledge of this work could help to enhance the seal design of pressure controllers for in-situ pressure-preserved coring.

可伐合金预氧化工艺对金属-玻璃封接气密性的影响研究

可伐合金和硅硼玻璃是通过可伐合金表面的氧化物与玻璃互溶而紧密结合在一起的,因此可伐合金的预氧化工艺是金属-玻璃封接的关键工序,是直接影响金属-玻璃封接气密性的重要因素。基于空气预氧化方法分析预氧化温度、时间、曲线等工艺因素对可伐合金在空气中预氧化及封接外壳气密性的影响。结果表明,可伐合金在空气中的氧化层厚度随温度和时间单调增加,在500~550℃空气气氛中氧化15~20 min,可伐合金表面形成0.7~1.6μm厚的氧化层,金属-玻璃封接外壳可获得较高的气密可靠性。

金属U-E密封结构重复使用性能数值分析

液体火箭发动机金属密封结构工作在严苛的力热耦合环境中,其循环应力-应变行为和棘轮应变累积效应会显著影响密封环的回弹能力和疲劳寿命。基于统一黏塑性理论对其循环使用过程进行数值研究,采用Chaboche非线性随动硬化和饱和型各向同性硬化模型共同描述密封环基体材料的循环力学行为,分析了密封环经历8次循环使用过程中主副密封唇宏观接触合力的演化规律和局部塑性应变累积部位的损伤进程。结果表明:副密封经历循环力热载荷作用后,由于叠加了显著的棘轮应变,残余塑性应变和累积塑性应变远高于主密封,导致其回弹能力衰减快于主密封且疲劳寿命短于主密封,在重复使用过程中不能发挥冗余设计作用。此外,提高的介质压力和预紧力不足均会导致塑性应变的加速累积,进而影响密封环的循环压缩回弹性能和疲劳寿命,应在装配过程中注意控制预紧力。

芯轴式套管悬挂器金属密封设计及性能分析

为了避免芯轴式套管悬挂器密封失效,根据芯轴式套管悬挂器的结构及密封工作原理,设计了一种新型的金属密封结构。建立了芯轴式悬挂器密封性能有限元模型,研究了不同顶丝压力和套管悬重对密封锥面变形及接触压力的影响。结果表明:随顶丝推力的增加,上、下密封锥面上平均接触压力都增加,有利于实现密封;随套管悬重的增加,上密封锥平均接触压力增加,下密封锥平均接触压力减小,除下内锥面外,均能满足密封要求。研究结果可为芯轴式悬挂器密封部位的结构设计提供参考。

高温全金属可溶桥塞的研发与应用

全金属可溶桥塞作为最新的井下压裂分段工具,现场应用越来越广泛,但限于金属材料的特性,桥塞在高温条件下(≥120℃)的性能极不稳定。根据全金属可溶桥塞在高温条件下的特点,优选镁铝合金材料,优化桥塞结构,加工出满足设计要求的高温全金属可溶桥塞,并参考可溶桥塞行业标准要求,进行了室内测试评价。目前该高温桥塞已在现场进行了大量的应用,承压和溶解效果良好,满足现场施工要求。

面向磁流体增强的骨架结构微成型设计及回弹特性研究

为提高磁流体密封液膜的刚度和抗压力性能,设计一种应用于磁流体密封的翻边Z型增强骨架,该骨架由软磁金属薄板微成型冲压而成。对软磁金属电工纯铁和无取向硅钢进行单向拉伸试验,得到2种材料的应力应变曲线。利用幂硬化准则对Z型骨架成型回弹特性进行理论分析,确定影响回弹的主要因素为材料参数、厚度、弯曲半径、开孔宽度等。利用有限元软件对成型回弹过程进行仿真,应用因素水平分析,以残余应变和最大回弹量为指标,分析板胚厚度、弯曲半径、开孔宽度对回弹的影响。仿真结果表明:在研究的范围内通过增大板胚厚度、减小弯曲半径、减小翅片宽度能有效降低骨架回弹;当厚度为0.3 mm,弯曲半径0.3 mm,翅片尺寸为2 mm×1 mm时骨架成型回弹量最小,运用硅钢材料比纯铁具有更小的回弹量。研究结果对软磁金属的微成型冲压及磁流体密封复合材料设计提供了参考。

林业汽车起重机液压缸杆密封件金属橡胶性能仿真研究

现阶段常见的橡胶密封圈在高温情况下易老化,在油液介质下易腐蚀,在高强度运输下易发生损坏。而主要应用于苛刻工况下密封领域的金属橡胶材料具有工作温度范围大、承载能力强、不易老化等特点。基于金属橡胶材料的优越性能,通过分析液压缸泄露原因,利用ANSYS分析MR组合密封件与普通O型橡胶密封性能的差异,对比不同密封件在相同边界条件下的接触应力与塑性变形,得出金属橡胶组合密封件在汽车起重机液压油缸的密封中更具有优势的结论。

基于金属屑传感器密封性改进设计

金属屑传感器已成为机械设备健康状态监测和故障诊断的重要手段。结构式金属屑传感器具有结构简单、吸附磁性粒子强等优点。然而,受到环境压力和温度变化等因素影响,导致传感器连接器输出端容易出现泄漏现象。本文对传感器这类故障的原因进行了分析,并通过采用玻璃烧结的方法实现了外壳和插针材料的连接,对传感器进行了改进设计。经验证,方案可行,产品性能可靠,能够实现金属屑的监测功能。

柔性石墨金属复合结构密封垫片研究进展

新型碳材料中,柔性石墨因其高耐候、抗辐射、低膨胀和良好的自润滑性而得到广泛应用,被誉为“当代密封之王”。但由于柔性石墨的多孔性、吸油性、低强度等缺点导致服役中易出现压溃、散架状况,严重制约了该材料的应用推广。柔性石墨复合材料兼具石墨和金属两者的优异性能,能够形成多道密封,逐渐成为石油、化工、汽车、核电等领域极端工况下密封材料的首选材料。文章分析了复合垫片的结构形式以及构成情况,并对石墨密封件在石化、核电等领域的应用前景和发展趋势进行了展望。

封孔处理对拖拉机热喷涂金属涂层耐腐蚀性的影响

封孔处理是指使用特定的封孔材料填补和封闭拖拉机热喷涂金属涂层中的微小孔隙和裂缝,有效增强农业拖拉机涂层的田间耐腐蚀特性。该文通过选取特定的基体材料、热喷涂材料和封孔材料,对拖拉机封孔前后耐腐蚀性能进行测试。结果表明,封孔处理显著提高了拖拉机热喷涂金属涂层的耐腐蚀性能,封孔后的金属涂层在模拟农田环境中表现出更高的抗化学侵蚀能力、更低的孔隙率和更好的耐磨损性能,说明封孔不仅提升了耐腐蚀性,还增强了涂层的整体机械强度。

金属盖板镀层形貌对平行缝焊器件抗盐雾性能的影响

气密性封装是高可靠集成电路制造的关键技术。探讨了金属盖板表面镀层形貌对平行缝焊器件耐盐雾性能的影响。研究发现,平行缝焊后金属盖板表面出现的贯穿性裂纹是降低平行缝焊器件耐盐雾性能的关键因素。在相同封帽参数下,表面镀层为长条形晶胞的盖板封帽后出现多条贯穿性裂纹,无法通过24 h盐雾试验后气密性检测。而表面镀层为均匀大小的圆形晶胞的盖板具备更高的抗封帽裂纹能力,封帽后无贯穿性裂纹出现,且可通过48 h盐雾试验后气密性检测。

基于虚拟制备的大环径比O形金属橡胶密封件结构性能研究

金属橡胶密封件(MRS)作为一种新型轻质弹性金属结构,可以替代传统聚合物材料密封件在极端环境中使用。但由于MRS结构的复杂与制备工艺的繁琐,MRS结构特性与力学性能无法精确设计而影响了工程应用。针对这一不足,基于计算机仿真技术,对大环径比O形MRS的制备工艺流程进行数值模拟,采用虚拟制备构建可以真实反映MRS宏观力学性能及微观复杂结构的模型,并依据实际工况对MRS不同压缩工况下的模型进行静力学仿真分析,分析压缩率对于密封系统摩擦界面的接触特性及其结构响应的影响,结果表明其接触特性受到压缩工况及包覆层塑性失效的共同作用。以静力学仿真输出的细观接触应力为参量,结合间隙流动模型,对密封件泄漏率进行仿真和计算,分析其泄漏率的影响因素,结果表明在密封件不发生塑性失效的前提下,较大的压缩率可以减少泄漏。研究结果对新型宽温域密封件的参数设计、性能研究与推广应用有一定的指导意义。