原文：
           1、前言  安全阀是一种目前被石油、化工行业的在用锅炉、压力容器广泛采用的安全泄压装置。而弹簧式安全阀是其中比较典型的一种。它是采用弹簧的压力作用为加压载荷，并通过调节弹簧压力的大小来调整安全阀的开启压力。当系统中压力超过允许值后，它能够自动开启并把过剩的系统介质排到大气或低压系统中，从而达到泄压的目的。当压力降到某一数值时，它又能自动迅速关闭，维持系统的正常运行。

         2、影响安全阀密封的原因分析  几年来，作者通过对在用安全阀的使用、检修和试验中，总结出在通常情况下，影响密封效果的原因主要有如下几点：

 2.1、安全阀关闭件的结构形式  关闭件的结构型式与应用场合的温度、力有关。因此，在更换安全阀关闭件时，不要随意改变关闭件型式。对于检修中更换了关闭件的阀，平衡阀如果在常温下已用标准介质试验合格，而当将其安装在被保护系统的介质压力温度下时，关闭件即发生早期泄漏，则应考虑关闭件结构是否合理。在检修方法和介质清洁度无误时，关闭件结构形式的不当，有时也表现在发生初次起跳回座后的密封不良。

 2.2、关闭件的材质、硬度及设计尺寸方面的影响  在安全阀的设计中，对关闭件材料、密封表面硬度的考虑，在检修和更换关闭件时，应十分注意，不得任意改变。由于介质对关闭件的腐蚀，液位计造成密封不良的事例比较常见。例如，在更换尿素装置中甲胺系统安全阀关闭件时，尽管选用了优质不锈钢，却因材料中含碳量超高而被甲胺腐蚀造成密封不良。当被保护系统无介质压力作用时，关闭件密封面要承受弹簧产生的压力，若密封面没有足够的硬度时，将会产生较大变形，导致密封不良，脆性材料可能有足够的硬度，但在阀起跳时，由于密封面反复被碰撞，有可能造成密封面碎裂，导致阀的泄漏。另一方面，抗腐蚀性很好的材料，若表面硬度差，在高压情况下，经受不了介质流对其表面的机械磨损，也会造成密封不良。

  2.3、密封面的宽度和加工精度的影响  实际上，阀瓣与阀座密封面之间存在着毛细管作用。密封面的宽度决定了介质通路的长度。因而，随着密封面宽度的增加，介质外漏时遇到的阻力以及对毛细管的堵塞作用随之增加。为此，在检修中随意削窄密封面宽度的做法是不妥的。过滤器在同等条件下，削窄密封面的宽度能降低阀的开启压力值；尽管加宽密封面能增加密封性，但在安全阀关闭末了和开启以前，受介质压力作用的阀瓣面积减小，从而也提高了安全阀的开启压力值。

  当设备长期停运时，因安全阀中无介质压力，弹簧的全部力作用在密封面上，若密封面宽度过窄，在较大的比压力作用下，可能造成密封面损伤，引起密封不良。实验证明，为了减少阀瓣、阀座互相压出沟槽的可能性，把平面性密封的阀瓣、阀座密封面加工成同样的宽度效果较好。  密封面表面质量的好坏，直接影响关闭件密封性。密封面的几何精度和表面光洁度与密封性有很大的关系。由于加工方法不当，金属密封面在加工中出现的微观不平以及波纹都会影响密封效果。目前我们检修时惯用回转式研磨方法，使密封面边缘低陷，密封性差。

  2.4、装配质量方面的影响  安全阀解体后的再装配，也会对密封面质量产生影响。针型阀通常由于装配不当会破坏关闭件的同轴度，使密封面不平行，导致密封不良。阀瓣使用时间过久，导向部分磨损严重或更换阀瓣时，导向间隙选配过大，造成阀瓣在动作中密封面歪斜。更换阀瓣时，导向间隙选用过小，生阀瓣动作时的卡阻，使密封面不能正确完好的关闭，导致密封不良。由于弹簧变形或装配位置不对，使弹簧在密封面四周的力分布不均匀，造成密封面比压力不均，使密封面局部密封性差。  安装或装配的应力会引起阀体的变形，使关闭件同轴度变动，密封线偏移，破坏了密封面的平行度，造成密封不良。实践证明，在这种情况下，密封面越宽，阀座直径越小，工作压力越高，密封面破坏的可能性就越大。

  2.5、被保护系统工作介质的影响  在同等压力、温度情况下，粘性大的介质比粘性小的介质泄漏量要小。液体介质比气体介质易密封。因此要考虑到阀设计时的许用介质。锻钢阀门介质温度会引起密封面热变形，在密封材料中会造成热梯度，引起密封面翘曲。所以，这些安全阀在常温介质下，密封实验结果良好，而安装在高温介质的设备上时，密封性则较差。为此，检修后对安全阀进行密封试验时，要考虑到介质的工作温度。密封面的寿命还与介质压力的稳定性有关，压力波动太大，会引起安全阀频繁起跳，使密封面在较短的时期内损坏。

      3 、结束语  综上所述，导致弹簧式安全阀密封不良的因素很多，而且这些因素之间的关系也很复杂，要想保证安全阀密封状况良好，保障被保护系统的安全性，需要设计、安装、使用、维护、校验等各方面人员认真细致的做好各方面的工作。

“On the impact of the main spring-loaded safety valve seal ”是由中国安全阀网提供的国际阀门新闻，译文仅供参考。另外，中国安全阀网还提供相关产品搜索： 全启式安全阀、 封闭式安全阀、 高压安全阀、 锅炉安全阀、 蒸汽安全阀、等。

译文：
        1 Introduction ? Safety valve is currently the oil and chemical industries in the use of boilers, pressure vessels widely used safety relief valve. The spring-loaded safety valve is a typical one. It is used for the compression spring pressure load, and by adjusting the spring pressure to adjust the size of the safety valve opening pressure. When the system pressure exceeds allowable value, it automatically opens and the excess medium discharged to the atmosphere or low pressure system, the system, so as to achieve relief purposes. When the pressure drops below a certain value, it can quickly turn off automatically to maintain the normal operation of the system. ? 2 Analysis of impact of safety valve seal ? The past few years, the author through the use of safety valve in use, maintenance and testing, summed up under normal circumstances, affect the seal of the main reasons are the following: ? 2.1, the safety valve closed parts of the structure ? Shut down parts of the structure types and applications of temperature, force the. Therefore, the replacement valve closure pieces, do not arbitrarily change the type of closed cases. Closed for repair parts in the replacement of the valve, if Zai Xia room temperature testBalance Valves has been Yong Biao Zhun Ge Ge media, while Dang install it in Pi Baohujitong of Jiezhi O'clock under pressure to temperature, turn off the parts that occur Zaoqi leak, should be considered down part Jiegou is reasonable. Maintenance of cleanliness in the correct methods and media, the closed structure of improper parts, and sometimes also in the back seat took place after the initial sealing off bad. ? 2.2, shut down parts of the material, hardness and size aspects of the design ? In the design of safety valve, the closure of parts material, sealing the surface hardness of the consideration, in the maintenance and replacement of closed cases should be great attention, shall not be changed arbitrarily. As the corrosion medium on the closure of parts, resulting in poor sealing of the more common examples. For example, in replacement of urea plant shut down parts of Methylamine system when the safety valve, while selected high-quality stainless steel, high carbon content because of the material was sealed methylamine corrosion caused by bad. When no medium pressure protection systems, close the piece sealing surface to withstand the pressure generated by spring, if the hardness of the sealingSafety Relief Valves surface is not enough, it will have a greater deformation, resulting in poor sealing, brittle material may have sufficient hardness, but In the valve off, due to the sealing surface was repeatedly collision, fragmentation may cause the sealing surface, resulting in valve leakage. On the other hand, a good anti-corrosive material, if the surface hardness is poor, in high pressure circumstances, the media stream can not stand the mechanical wear and tear on its surface will result in poor sealing. ? 2.3, the width of the sealing surface and the machining accuracy ? In fact, the valve flap and valve seat sealing surface exists between the capillary action. Determines the width of the sealing surface of the length of the media channels. Thus, with the sealing surface width increases, the dielectric leakage resistance encountered and the blocking effects of increased capillary. To this end, a narrow cut in the maintenance of the free practice of the width of the sealing surface is inappropriate. Under the same conditions, cut the width of narrow sealing surface Instrumentation Ball Valvescan reduce the valve opening pressure value; While widening the sealing surface can increase the tightness, but closed in the safety valve to open before the end of the age and by medium pressure valve valve area decreased thus improve the safety valve opening pressure value. ? When the device long-term outages, due to the pressure relief valve in the non-media, all the force of the spring in a sealed surface, if the narrow width of the sealing surface, the pressure in the larger role than under the sealing surface may cause damage, cause seal bad. Experimental results show, in order to reduce the valve flap, seat the possibility of mutual pressure groove, the plane of the valve seal valve, the valve seat sealing surface processed into the same width is better. ? Sealing surface surface quality are directly affected by closure sealing parts. Sealing surface of the geometric accuracy and surface finish and sealing a great relationship. Due to improper processing, metal processing occurs in the sealing surface uneven and corrugated microstructure will affect the seal. Currently we overhaul the usual rotary grinding method to seal edges Dixian, poor sealing. ? 2.4, the quality of assembly ? After the disintegration of a further safety valve assembly, will also impact on the quality of the sealing surface. Usually due to improper assembly will be shut down parts of the coaxial damage to sealing surfaces are not parallel, leading to poor sealing. Disc used forNeedle & Gauge Valves too long, driven some serious wear and tear or replacement disc, the orientation matching gap is too large, causing the valve flap sealing surface of skew in the action. Replacement disc, the orientation chosen gap is too small, health cards when the valve flap resistance movement, so well-sealed surface can not properly shut down, resulting in poor sealing. As the spring deformation, or assembly location does not make spring force in the sealing surface around the uneven distribution of pressure caused by uneven sealing surface than to the local seal sealing surface difference. ? Installation or assembly of stress will cause deformation of the valve body to close the piece coaxial change, seal line offset, destroyed the sealing surface of parallelism, resulting in poor sealing. Practice shows that in this case, the wider the sealing surface, the smaller the diameter of the valve seat, the higher the pressure of work, sealing surface damage more likely. ? 2.5, was the work of mediators in the protection system ? At the same pressure, temperature conditions, the viscous medium large small medium than the viscous leakage is smaller. Liquids than gases easily sealed. Therefore, taking into account the allowable valve design media. Medium temperature will cause thermal deformation of the sealing surface, the sealing material will cause thermal gradient, Instrument Manifoldscausing the sealing surface warping. Therefore, these media at room temperature under the safety valve, good sealing results, while installed in the high-temperature media device, the sealing is poor. To this end, after the valve seal repair test, taking into account the medium temperature. The life of the sealing surface with the stability of the medium pressure, pressure fluctuations, will cause frequent take-off safety valve, so that sealing surface damage in a relatively short period of time. ? 3, Conclusion ? In summary, spring-loaded safety valve seals cause adverse factors, and relationship between these factors is complex, in order to ensure good sealing safety valve to protect the security of the protected system, need to design, installation, use, maintenance, validation and other aspects of officers carry out all serious and careful work.

原文来源：http://www.1anquanfa.com/

2010-08-30 08:12

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