Flanges are used to connect pipes with each other, to valves, to fittings, and to specialty items such as strainers and pressure vessels. A cover plate can be connected to create a “blind flange”. Flanges are joined by bolting, and sealing is often completed with the use of gaskets or other methods.
Types of Stainless Steel Flanges
Weld Neck Flanges
A Weld Neck Flange (which can also be known as a high-hub flange or a tapered hub flange) consists of a circular fitting with a protruding rim around the circumference. Weld neck flanges are usually forged and then are typically butt-welded to a pipe which successfully transfers stress away from the flange and onto the pipe instead.
Slip-On Flanges
A Slip-On Flange slips over the pipe, or possibly elbow, that they are being joined to. To allow this to happen, they are specifically manufactured so that their inside diameter is slightly bigger than the pipe’s outside diameter. Slip-On Flanges are then connected to the pipe via a ‘fillet weld’ at the top, bottom, inside and outside of the flange which ensure the strength of the join.
Socket-Weld Flanges
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.
Blind Flanges
Essentially, a Blind Flange is a plate for covering or closing the end of a pipe to block off a section of pipe or a nozzle on a vessel that is not used. It also allows easy access to the interior of a line or vessel if it needs to be reopened after it is sealed.
Lap Joint Flanges
Lap Joint Flanges consist of two parts; A stub end and the backing flange. A pipe is usually welded to the Stub End via a gasket and then the backing flange is not welded or fixed in any way which means it is free to rotate around the stub end for proper alignment with whatever it is joining to.
Threaded Flanges
The threaded flange design (also called a ‘screwed flange’) uses a screw thread to connect the flange to a pipe. A male thread is cut onto a pipe end whilst a female thread is cut into the bore of the flange; the male threaded pipe is then screwed into the female threaded flange.
| Duplex & Super Duplex | UNS S32750, UNS S32760, UNS S31803 |
| Hastelloy Alloys | ASTM B564 Hastelloy B2, C276, C22 |
| Incoloy Alloys | ASTM B564 Alloy 20, Alloy A286, Alloy 800H/800HT, Alloy 825 |
| Inconel Alloys | ASTM B564 Alloy 600, Alloy 601, Alloy 625, Alloy 718, Alloy 725 |
| Monel Alloys | ASTM B564 Monel 400, Monel K500 |
| Stainless Steel | ASTM A182, F304, 304L, 304H, 310, 316, 316L, 317, 317L,321, 347, 904L |
| Carbon Steel | ASTM A105, A694 F42, A350 LF2 |
| Alloy Steel | ASTM A182 F1, F5, F9, F11, F22, F91 |
| Size | 1/2″NB to 72″NB |
| Class | 150#, 300#, 600#, 900#, 1500# & 2500# |
| Types | Plate Blank Flange, Screwed Flange, Lap Joint Flange, Socketweld Flange, Weldneck Flange, Blind Flange, Oriface Flange, RTJ Flange, Long Weldneck Flange, Threaded Flange, Slip-On Flange, Spectacle Flange |
