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Introduction To The Working Characteristics Of Ultra - Low Temperature Butterfly Valve

Oct 11, 2017

Flange butterfly valve material selection, and strive to stainless steel stem, large diameter valves should also be stainless steel embedded package stem; due to gray cast iron pipe is not recommended to use, the valve body material should be dominated by ductile iron, and indicate grades and castings The actual physical and chemical testing data nut material, the use of cast aluminum brass or cast aluminum bronze, and the hardness and strength are greater than the stem stem material, its hardness and strength should not be greater than the stem, and in the water immersion With the stem, the valve body does not form electrochemical corrosion.Butterfly Valve

Different types of valves, in the ship pipe and installation of the space, quality and performance are significantly different. In low-temperature systems, such as the use of ball valves, gate valves or plug valves as open and closed parts, because the valve closed state there is a closed cavity (the ball in the fully open position also formed a confined space) and filled with media The temperature gradually increased in the valve cavity in the low temperature liquefied natural gas will occur gasification phenomenon, increasing the volume of about 600 times, resulting in rapid increase in the pressure inside the valve chamber, is likely to exceed the pressure allowed by the valve body.Butterfly Valve If the valve chamber pressure can not be released, will produce a very serious security incidents. The ultra-low temperature butterfly valve in the structure to avoid the valve cavity medium abnormal boost phenomenon, without the use of internal and external discharge methods, or external discharge gas collection device to solve the problem of abnormal pressure in the valve cavity, to ensure that the environment and equipment Safety.Butterfly Valve

Usually LNG marine ultra-low temperature butterfly valve operating temperature of about 163 ℃ below, at this temperature, the valve metal material will produce low temperature cold brittle phenomenon, that is, the material hardness and brittleness increased plastic and toughness decreased, thus affecting the valve performance and System is safe to use. In order to prevent the valve material in the case of low temperature brittle fracture, usually in the design of ultra-low temperature valve, the valve body, valve plate, seal seat, stem, packing and fasteners, and most of its pressure parts with face Cubic lattice of austenitic stainless steel.Butterfly Valve