A flange is disc, collar or ring that attaches to pipe with the purpose of providing increased support for strength, blocking off a pipeline or implementing the attachment of more items. Pipe flanges are usually welded or screwed to the pipe end and are connected with bolts. A gasket is inserted between the two mating flanges to provide a tighter seal. Flanges are either custom with dimenions provided by the customer or they are manufactured or imported according to published specifications. Several organizations and associations have published specifications that provide dimensional information as well as pressure specifications at different temperatures.
Slip-on pipe flanges actually slip over the pipe. These pipe flanges are typically machined with an inside diameter of the pipe flange slightly larger than the outside diameter of the pipe. This allows the flange to slide over the pipe but to still have a somewhat snug fit. Slip-on pipe flanges are secured to the pipe with a fillet weld at the top and the bottom of the slip-on pipe flanges. These pipe flanges are also further categorized as a ring or a hub. Ring pipe flanges and hub pipe flanges are both considered slip on pipe flanges because they both slip over the pipe. Slip on Pipe flanges with a hub has published specifications that range from 1/2″ thru 96″. Slip on pipe flanges that consist of a flat ring have published specifications that range from 1/2″ thru 144″.
WELD NECK FLANGES
Weld neck pipe flanges attach to the pipe by welding the pipe to the neck of the pipe flange. The allows for the transfer of stress from the weld neck pipe flanges to the pipe itself. This also reduces high stress concentration at the base of the hub of the weld neck pipe flanges. Weld neck pipe flanges are often used for high pressure applications. The inside diameter of a weld neck pipe flange is machined to match the inside diameter of the pipe. Weld Neck Pipe flanges with a hub have published specifications that range from 1/2″ thru 96″.
Blind pipe flanges are pipe flanges used to seal the end of a piping system or pressure vessel openings to prevent flow. Blind pipe flanges are commonly used for pressure testing the flow of liquid or gas through a pipe or vessel. Blind pipe flanges also allow easy access to the pipe in the event that work must be done inside the line. Blind pipe flanges are often used for high pressure applications. Slip on Pipe flanges with a hub has published specifications that range from 1/2″ thru 96″.
LAP JOINT FLANGES
Lap Joint Pipe Flanges slide over the pipe and are most commonly used with Stub End Fittings. A pipe is typically welded to the Stub End and the Lap Joint pipe flange is free to rotate around the stub end. The benefit of this is that there will not be any issues with bolt hole alignment. Lap Joint pipe flanges are often used for applications that require frequent dismantling. Slip on Pipe flanges with a hub has published specifications that range from 1/2″ thru 24″. Sizes above 24″ are produced as lap joints to slip on dimensions.
Threaded pipe flanges are similar to slip-on pipe flanges except the bore of threaded pipe flange has tapered threads. Threaded pipe flanges are used with pipes that have external threads. The benefit of these pipe flanges is that it can be attached without welding. Threaded pipe flanges are often used for small diameter, high pressure requirements. Slip on Pipe flanges with a hub has published specifications that range from 1/2″ thru 24″.
Socket-weld pipe flanges are typically used on smaller sizes of high pressure pipes. These pipe flanges are attached by inserting the pipe into the socket end and applying fillet weld around the top. This allows for a smooth bore and better flow of the fluid or gas inside of the pipe. Slip on Pipe flanges with a hub has published specifications that range from 1/2″ thru 24″.
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