WELDING NECK FLANGES
THE WELDING NECK FLANGE is normally referred to as the "high hub" flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange. The welding neck flanges is the best designed butt-welded flange of those currently available because of its inherent structural value.

SLIP-ON FLANGES
THE SLIP-ON FLANGE has a low hub because the pipe slips into the flange prior to welding. It is welded both inside and out to provide sufficient strength and prevent leakage. Slip-On flanges are all bored slightly larger than the outside diameter of the matching pipe. They are preferred over welding neck flanges by many users due to their lower initial cost, but final installation cost is probably not much less than that of the welding neck flange because of the additional welding involved.

BLIND FLANGES
THE BLIND FLANGE id a flanges without a bore. It is used to close off the ends of a piping system and/or pressure vessel opening. It also permits easy access to the interior of a line or vessel once it has been sealed and must be reopened.

SOCKET WELDING FLANGES
THE SOCKET WELDING FLANGE is similar to a slip-on flanges except it has a bore and a counterbore dimension. The counterbore is slightly larger than the outside diameter of the matching pipe, allowing the pipe to be inserted into the flange similar to a slip-on flanges. The diameter of the smaller bore is the same as the inside diameter of the matching pipe. A restriction is built into the bottom of the bore which sets as a shoulder for the pipe to rest on. This eliminates any restriction in flow when using a socket welding flanges.

THREADED(SCREWED) FLANGES
THE THREADED FLANGE is similar to the slip-on flange, but the bore is threaded. Its chief merit is that it can be assembled without welding, explaning its use in low pressure services at ordinary atmospheric temperatures, and in highly explosive areas where welding createa a hazard.

LAP JOINT FLANGES
THE LAT JOINT FLANGE is preactically identical to a slip-on flanges except it has a radius at the intersection of the bore and flanges accommodate a lap joint stub end. Normally, a lap joint flanges and a lap joint stub end are matched together in an assembly system.