Flanges

Slip-on pipe flanges actually slide over the pipe. They are typically machined with an inside diameter 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-ons are secured to the pipe with a fillet weld at the top and the bottom of the flange. These are further catagorized as a ring or a hub. Rings and hubs are both considered slip on flanges because they both fit over the pipe.

Blind pipe flanges are used to seal the end of a piping system or pressure vessel openings to prevent flow. They are commonly used for pressure testing the flow of liquid or gas through a pipe or vessel. They 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.

Weld neck pipe flanges are installed by welding the pipe to the neck of the flange. This allows for the transfer of stress from the flange to the pipe itself. This also reduces high stress concentration at the base of the hub. Weld necks are often used for high pressure applications. The inside diameter of this attachment is machined to match the inside diameter of the pipe.

Socket-weld pipe flanges are typically used on smaller sizes of high pressure pipes. These 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.

Threaded pipe flanges are similar to slip-ons except the bore of threaded pipe flange has tapered threads. They are used with pipes that have external threads. The benefit of these is that it can be attached without welding. Threaded pipe flanges are often used for small diameter, high pressure requirements.