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新的法兰密封方法

         几十年来,美国国家标准学会设计的ANSI法兰已经为石油和天然气工业提供了一种适用的密封技术,而且卓有成效。但由于石油天然气工业的需求已经发生变化,ANSI法兰的缺陷不断暴露出来。成本效益原则、环境保护以及最佳的健康和安全保证是21世纪的作业者和承包商所面对的三大课题,因此,人们开始考虑新的法兰密封方法。
  ANSI法兰的密封原理极其简单:螺栓的两个密封面相互挤压法兰垫片并形成密封。但这同时也导致密封的破坏。为了保持密封,就得维持巨大的螺栓作用力。为此,螺栓就要做得更大。而更大的螺栓就要匹配更大的螺母,这就意味着需要直径更大的螺栓为上紧螺母创造条件。殊不知,螺栓的直径越大,适用的法兰就会变得弯曲,唯一的办法就是增大法兰部分的壁厚。整个装置将需要极大的尺寸和重量,这在近海环境下便成了一个特殊问题,因为在这种情况下重量始终是人们必须引起关注的主要问题。而且,从根本上来说,ANSI法兰是一种无效的密封,它需要把50%的螺栓负荷用于挤压垫片,而用于保持压力的负荷只剩50%。
  然而,ANSI法兰的主要设计缺点是它不能保证无泄漏。这就是其设计上的不足:连接是动态的,而且诸如热膨胀和起伏不定的周期载荷都会造成法兰面之间的移动,影响法兰的功能,从而使法兰的完整性受损,最终导致泄漏。
  由Vector公司最新开发的新型法兰克服了ANSI法兰的缺点。紧凑的法兰具有各方面的优点:标准法兰不仅节省了空间、减轻了重量,更重要的是确保接头部位不会发生泄漏。紧凑法兰尺寸之所以减小,是由于减小了密封件的直径,这将会减小密封面的截面。其次,法兰垫片已被密封环所代替,以确保密封面对密封面的匹配。这样一来,为了压紧密封面仅需要很小的压力。随着所需压力的降低,螺栓的尺寸和所需数量都可相应减小。最终设计出了一种体积小且重量轻(比传统的ANSI法兰的重量减轻70%~80%)的新产品。

For decades, the American National Standards Institute ANSI flange design for the oil and gas industry provides a seal applied technology, and effective. However, due to the demand for oil and natural gas industry have changed, ANSI flange continuously exposed shortcomings. The principle of cost-effectiveness, environmental protection and the best guarantee of health and safety operations in the 21st century and contractors are facing three major issues, so people began to consider a new method of sealing flange.
ANSI flange sealing principle is extremely simple: the two bolts each other extrusion flange sealing surface and form a seal gasket. But at the same time lead to seal damage. In order to maintain the seal, you must maintain the tremendous force of the bolt. To this end, the bolts should be doing more. A bigger bolt nut must match the larger, which means that larger diameter bolts need to create conditions on the tight nut. As everyone knows, the greater the diameter of bolts for the flange would be bent, the only way is to increase the flange part of the wall thickness. The entire device will need a great size and weight, which in the coastal environment has become a special problem because the weight in such circumstances has always been to be the main issues of concern. Moreover, essentially, ANSI flange is an invalid seal, which need to be 50% of the bolt load for gasket extrusion, while maintaining pressure on the load for only 50%.
However, ANSI flange design of the main shortcomings is that it can not guarantee no leakage. This is less than its design: the connection is dynamic, and thermal expansion, such as fluctuations in the cycle and the load will cause the movement between the flange and affect the function of the flange, so that damaged the integrity of the flange, which eventually led to leakage.
Vector's latest development by the new flange to overcome the shortcomings of the ANSI flange. Compact flange with all the advantages: standard flange not only saves space, thereby reducing the weight and, more importantly, to ensure that there will be no leakage of joint positions. The reason why reducing the size of a compact flange, as a result of reduced diameter seals, which will reduce the sealing surface of the section. Secondly, the flange gasket sealing ring has been replaced to ensure that the sealing face of sealing surface of the match. As a result, the pressure to close the cover requires only a very small pressure. With the pressure required to reduce the size of bolts and the numbers required can be reduced accordingly. The final design of a small size and light weight (than the traditional ANSI flange weight by 70% ~ 80%) of new products.

 

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