A swivel flange is a two-piece mechanical device combining a heavy welding hub (which is welded to the pipe) with a rotating ring with bolting holes which can be mated with another welding neck flange or any other compatible flange easily and quickly. A swivel flange features a retaining ring to hold the rotating ring in position during the installation.
Swivel ring flanges facilitate the alignment of the bolt holes between the two mating flanges, a feature that is helpful in many circumstances, such as the installation of large diameter pipelines, subsea and offshore pipelines, pipe works in shallow waters and similar environments. Swivel flanges suit oil, gas, hydrocarbons, water, chemical and other demanding fluids in petrochemical and water management applications.
In the case of a large diameter pipeline, for instance, the pipe is fitted, at one end, with a standard welding neck flange, and with a swivel flange at the other end: by simply rotating the swivel flange on the pipe, the operators can achieve a perfect alignment of the bolt holes in a way easier and faster way.
The major standards for swivel ring flanges are ASME/ANSI, DIN, BS, EN, ISO, etc. The most common standard for petrochemical application is the ANSI/ASME B16.5 or ASME B16.47
SWIVEL FLANGE TYPES
Swivel flanges are available in all the standard shapes of common flanges, i.e. weld-neck, slip-on, lap-joint, socket weld etc, in all material grades and in a wide dimensional range (sizes can vary from 3/8” to 60” and pressure rating from 150 to 2500).
SWIVEL FLANGE MATERIALS
Swivel flanges can be manufactured in carbon steel (ASTM A105), alloy steel (ASTM A182 F1, A182 F5, A182 F9, A182 F91), and, stainless steel (ASTM A182 F304, A182 F304L, A182 F316, A182 F316L). For more information about the materials for forged flanges, refer to this article.