Some questions regarding the inlet flange and outlet flange of the spring-loaded safety valve
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The last edit to this post was made by feng_200108047 on 2011-12-21 at 08:36. I would like to ask why the inlet flange of a spring-loaded safety valve is designed to be a convex flange, while the outlet flange is a flat flange? Which is larger, the diameter of the inlet or the diameter of the outlet? Why? Thank you so much
The flange faces differ due to different pressure ratings； High inlet pressure, small flange size; low outlet pressure, large volume, large flange size ；
So, is it true that convex flanges are used for higher pressure levels and flat flanges for lower pressure levels? Is the side that connects to the safety valve also fitted with a convex flange? Thank you! ! !
Reply to 3# zhou6089: Flat flanges are easy to manufacture and cost less. Convex flange: It offers good sealing properties and high pressure resistance, and is used when the medium is toxic and prone to leakage.
It seems that for the flange connections of safety valves, the minimum requirement is a convex RF flange; a better option is an RTJ grooved flange, and the best choice is a welded connection. Since the inlet pressure of the safety valve is generally very high, at least 14.5 psig or more, the pressure class of the inlet flange must be equal to or higher than that of the outlet flange. Moreover, the outlet must be larger than the inlet, so as to ensure that there are no obstacles to full discharge by the safety valve. Many liquids undergo flashing during discharge, causing their volume to increase rapidly; if the outlet is smaller than the inlet, it can easily lead to excessive pressure buildup and accidents.
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