BLIND FLANGES

backA flanged or cast ring of steel designed to connect section ofpipe or join pipe to a pressure vessel, valve, pump or any other integralsflanged assembly.flanges are joined to each other by bolting and joined to thepiping system by welding or threading.the basic type of flanges are : Slip On, Blind, Weld Neck,Threaded, Socket Weld, Lap Joint and Plate.Flanges are designed to the following pressure ratings: 150lb,300lb, 400lb, 600lb, 900lb,1500lb and 2500lb or 10 Bar, 15Bar, 25Bar, 40Bar,64Bar, 100Bar and 150Bar.The flange is slipped over the pipe and then welded both insideand outside to provide sufficient strength and prevent leakage. This flange isused in preference to weld necks by many users because of its lower cost and thefact that less accuracy is required when cutting pipe to length.This is a flange without a bore and is used to shut off a pipingsystem or vassal opening. It also permits easy access to vassal or piping systemfor inspection purpose. Blind flanges can be supplied with or without hubs atthe manufacturer's option.This is designed to be joined to a piping system by buttwelding. It is relatively expensive because of its long neck, but is preferredfor high stresses to the pipe, reducing stress applications. The neck, or hub,transmits stress concentration at the base of the flange. The gradual transitionof thickness from the base of the hub to the wall thickness at the butt weldprovides important reinforcement of the flange. The bore of the flange matchesthe bore of the pipe, reducing troublence and erosion .This is similar to slip on flange in outline, but bore isthreaded, thus enabling assembly without welding. This obviously limits itsapplication to relatively low pressure piping systems. The flange may be weldedaround the joint after the assembly, but this is not consider a satisfactorymethod of increasing its applications.This is similar to a slip on flanges in outline, but the bore iscounter-bored to accept pipe. The diameter of the remaining bore is same as theinside diameter of the pipe. The flange is attached to the pipe by a fillet weldaround the hub of the flange. An optional interval weld may be applied in highstress applications. Its biggest use is in high pressure system such ashydraulic and steam lines.This is again similar to a slip flange, but it has radius at theintersection of the bore and the flange face to accommodate a lap stub end. Thenface on the stub end forms the gasket face of the flange. This type of theflange is used in applications where sections of piping systems need to be dismantledquickly and easily for inspection or replacement.This is usually used with a pressed collar or stub end and isplaced behind the collar or stub end. It is not welded and thus allows for easyalignment. Also permits use of other materials for the flange as the flange isnot in direct contact with the liquid.click here to see thespecification covering the manufacture and dimensions of flanges