密封垫片填料中可溶性氯离子含量测定方法研究

【作者】 陈中官；

【导师】 宋鹏云；

【作者基本信息】 昆明理工大学 ， 化工过程机械， 2007， 硕士

【摘要】 垫片和填料密封在现代工业中占有很重要的地位，密封失效严重地影响生产的连续性，密封的好坏直接关系到生产安全，因此垫片与填料的发展越来越受到人们的重视，然而国内外通常使用的垫片与填料在生产加工过程中或原料中含有一些可溶性的氯化物，在密封过程中这些可溶性氯化物游离出的氯离子可能使密封面、泵轴和阀杆引起腐蚀，导致泄漏率增大，进而破坏密封件的密封性能，甚至使密封失效。因此有必要研究挚片与填料中可溶性的氯离子含量的测定手段和方法，以及探讨可溶性的氯离子浓度对密封面、泵轴和阀杆的腐蚀影响。目前国内只有对柔性石墨板氯含量的测定，使用JB／T 6622-93（燃烧—硫氰酸汞分光光度法测定），对其它材质的挚片中的氯离子含量测定还没有相应的标准。本文通过对挚片与填料的游离氯离子溶出进行了试验研究，建立了离子选择法快速检测挚片与填料中的游离氯离子，设计了一个合理的挚片与填料的腐蚀实验。主要研究结果如下：1．通过对垫片或填料中的游离氯离子的溶出试验，本文得出了垫片与填料游离氯离子的溶出最优参数，即提取温度控制在90℃，垫片和填料溶液中的NaOH的浓度为0.01mol／L，提取时间为4个小时。并且对垫片与填料的粒度以及提取次数的效果进行分析，使得提取条件优化。2．分别用离子选择电极法和传统的分光光度法测定垫片和填料的游离的氯离子浓度，并且进行了对照试验，两种测定方法得出的结果平均相对误差为7％，因此离子选择电极法测定垫片与填料中的游离氯离子浓度是可行的，结果是可靠的。3．对于垫片与填料溶液中可能对离子选择电极产生干扰的离子，进行了一一分析，分别把这些离子的干扰消除。实验结果表明S^2-，Fe³⁺对离子选择电极干扰较大，本文分别用双氧水、酒石酸钠钾消除或者掩蔽，使得干扰很好消除。4．分别对绘制工作曲线的影响因素进行了实验研究，确定各个影响因素，使得工作曲线在1×10^-1mol／L～5×10^-5mol／L范围内呈线性关系，相关系数R=0.99705。5．分别对含有不同氯离子的垫片进行了腐蚀实验，通过与垫片相接触的不锈钢表面的腐蚀深度，确定出挚片或者填料中的氯离子含量上限，从实验得出氯离子含量在36μg／g以下不会腐蚀，超过50μg／g不锈钢有腐蚀迹象。本文所研究的氯离子选择法测定氯离子含量，方法简便、灵敏、受干扰因素少，可以避免原来的分光光度法所使用的试剂汞盐毒性太大的缺点。在腐蚀实验中得出氯离子含量的上限，可以为工厂生产垫片和填料，以及公司选用垫片和填料有个选择的标准。更多还原

【Abstract】 Gaskets and packings take an important role in modern industry. Productive continuity is influenced by the failures caused by seals. whether seal is good or not has something to do with productive security directly. The development of gaskets and packings is increasingly paid much more attention. However, generally speaking, gaskets and packings used in domestic and overseas contain leachable chloride during production process or raw materials, from which the leachable chloride dissociates. It is very likely that those leachable chlorides can cause corrosion to seal faces, pump shafts and valve-spindles, which leads to accelerate leakage rates and even destroys the seals. So it is necessary to study the test methods and means to the leachable chloride content in gaskets and packings and to discuss the influence the leachable chloride concentration has on corrosion effects to the seal faces, pump shafts and valve-spindles. So far, there are a few related test methods of chloride content about flexible graphite blanders by using corresponding criterion JB/T 6622-93, namely burning-mercuric rhodanate spectrophotometry. But there is no corresponding criterion about methods to test the chloride content of gaskets made by other materials.The related experiments were done to study the leaching of dissociative chloride ions in gaskets and packings. By ion-selective electrode technique, the method to test quickly the dissociative chloride ions in gaskets and packings was established in this paper. And then, corrosive experiments about gaskets and packings were designed reasonably. The results studied mainly contents the following points:1. Through the dissociative experiment to test leachable chloride in gaskets and packings, the leachable optimum parameters were obtained. That is, extracted temperature is controlled at 90℃; sodium hydroxide concentration in the liquor of gaskets and packings is 0.01mol/L; extraction time is 4 hours. And then, the granularity of gaskets andpackings is analyzed as well as the results of extraction times so as to optimize extraction conditions.2. Chloride ion-selective electrode technique and spectrophotometry were respectively adopted to test the leachable chloride content in gaskets and packings and then the experiment results were compared. The experiment showed that the average relative deviation （ARD） obtained by above two test methods is 7%. Therefore, it is feasible that chloride ion-selective electrode technique is adopted to test the leachable chloride in gaskets and packings and the results are reliable.3. The interference caused by the liquor of gaskets and packings was analyzed one by one and the interfere these ions cause were eliminated. The experiment result showed that S^2- and Fe³⁺ have a great influence on ion-selective electrode. So, the interference was eliminated or sheltered respectively by hydrogen peroxide liquor and potassium sodium tartrate in this paper. As a result, the interference was eliminated well.4. Each influential factor about plotting work curves was studied through experiment. By every influential factor confirmed, the work curves are linear within the range from 1×10^-1mol/L to 5 ×10^-5mol/L and the related coefficient R=0. 99705.5. The corrosion experiments about gaskets, which have different chloride ion content, were done to confirm the upper limit of chloride ion content in gaskets or packings through corrosion depth on stainless steel surfaces which contact with gaskets. From the above experiments, it proved that stainless steel didn’t encounter corrosion when chloride ion content is below 36μg/g and there are corrosion phenomena on stainless steel surfaces when chloride ion content exceeds 50μg/g.The traits to test chloride ion content by ion-selective electrode lie in its convenient, sensitive and less interfere factors. The disadvantage that reagent-mercury salt originally used in spectrophotometry is toxic heavily can be avoided. In the corrosion experiments, the upper limit of chloride ioncontent was obtained, which can properly supply a selective standard for industry that products and selects gaskets and packings.更多还原