Axial and universal unbalanced expansion joints

Design features of axial bellows expansion joints

Unbalanced bellows expansion joints take up loads from potential mechanical effects, vibrations from operating equipment and flow of transported medium, as well as thermal deformations of various pipeline elements due to changes in temperature of the transported and ambient media. At the same time, the unbalanced bellows expansion joints additionally transfer to fixed supports and mating equipment the separating force from the internal pressure action on walls of the bellows corrugations.

Axial unloaded bellows expansion joints, provided that the bellows stability is ensured, can also take up installation angular and lateral deformations, while performing their functions under conditions of axial action of connected structures, stretching or compressing along its axis within the elastic deformation of the bellows material.

Universal bellows expansion joint is an expansion joint that performs its functions under conditions of simultaneous action of connected structures in axial, angular and perpendicular directions of its axis.

Universal unbalanced bellows expansion joint can be considered an axial bellows expansion joint without installed restraining parts, excluding the risk of angular and lateral deformations of the bellows, which is simultaneously affected by axial, angular and lateral deformations during operation. At that, the expansion joint design shall ensure stability of the bellows.

Kompensator SPE, JSC manufactures the following types of universal bellows expansion joints:

Universal bellows expansion joint, type NOPN. Structurally, it is a bellows expansion joint, consisting of a bellows and welded neck branch pieces for welding to the pipeline. It is a basic product for more complex designs of bellows expansion joints, but it can be installed directly in pipelines.
Universal bellows expansion joint with an internal branch piece, type NOPG.
Universal unbalanced bellows expansion joint, type NOPK. Structurally, it is a bellows expansion joint consisting of a bellows and two flat flanges in accordance with GOST 12820-80, welded to the bellows through short connecting branch pieces. It has a stationary protective casing installed on one of the expansion joint branch pieces using bosses.
Universal bellows expansion joint, type NOPM. Axial bellows expansion joint with stationary protective casing installed on one of the expansion joint branch pieces using bosses, and with internal guide branch piece.
Universal bellows expansion joints, type NOFN.Structurally, it is a bellows expansion joint consisting of a bellows and two flat flanges in accordance with GOST 12820-80, welded to the bellows through short connecting branch pieces. All bellows corrugations have the same height, all bellows layers are made of stainless steel, material of the flanges corresponds to the material of the counter flanges.
Universal bellows expansion joints, type NOFG.Structurally, they represent bellows expansion joints of types NOFN and NOFK with a guide branch piece welded to the inner surface of one of the shortened branch pieces. All bellows corrugations have the same height, all bellows layers are made of stainless steel, material of the flanges corresponds to the material of the counter flanges.
Universal bellows expansion joints, type NOFK.Structurally, it is a bellows expansion joint consisting of a bellows and two flat flanges in accordance with GOST 12820-80, welded to the bellows through short connecting branch pieces. Lightweight protective casing is installed above the bellows. The removable casing is bolted to one of the flanges.
Universal bellows expansion joints, type NOVN.Structurally, it is a bellows expansion joint consisting of a bellows and two flat flanges in accordance with GOST 12820-80. Height of the first and last bellows corrugations is reduced in comparison with height of the remaining working corrugations in order to ensure bolting of the flanges. All bellows layers are made of stainless steel, material of the flanges corresponds to material of the counter flanges.
Universal bellows expansion joints, type NOVG.Structurally, they represent bellows expansion joints of type NOVN with a guide branch piece welded to the inner surface of one of the flanges.
Universal bellows expansion joints, type NOFM.Structurally, they represent bellows expansion joints of types NOFN and NOFK with a guide branch piece welded to the inner surface of one of the shortened branch pieces and with stationary protective casing.
Universal bellows expansion joints, type NOVM.Structurally, they represent bellows expansion joints of type NOVN with a guide branch piece welded to the inner surface of one of the flanges. Lightweight protective casing is installed above the bellows. The removable casing is bolted to one of the flanges.

Bellows expansion joints, types NOPN, NOPK, NOFN, NOFK, NOVN can be installed directly in pipelines carrying water (delivery and drinking water) under a temperature of up to 150 °С and at a flow rate of up to 8 m/s, oil and oil products under a temperature of up to 450 °С and at a flow rate of up to 8 m/s, as well as steam and gaseous media that do not corrode materials of the expansion joint under a temperature of up to 500 °C and at a flow rate of up to 20 m/s.

Bellows expansion joints, types NOPG, NOPM, NOFG, NOFM, NOVG, NOVM can be installed directly in pipelines carrying water (delivery and drinking water) under a temperature of up to 150 °С and at a flow rate exceeding 8 m/s, oil and oil products under a temperature of up to 450 °С and at a flow rate exceeding 8 m/s, as well as steam and gaseous media that do not corrode materials of the expansion joint under a temperature of up to 500 °C and at a flow rate from 20 to 80 m/s provided a branch piece is installed.

Bellows expansion joints of the NOPG, NOPM, NOFG and NOFM types are recommended to be used to compensate, mainly, for axial displacements of pipeline system, since due to the small clearance between the inner surface of the bellows and the guide branch piece, the risk of angular and lateral displacements of the bellows expansion joint is negligible.

! Pipelines, in which the bellows expansion joints with inner guide branch pieces are installed, may not be used in reverse mode: working fluid shall move through the pipeline in a strictly defined direction.