Single-hinge Expansion Joint

Single Hinged Expansion Joint Overview

A single hinged expansion joint is a metal bellows assembly designed to accommodate angular movement in one plane. It is commonly installed in pipeline bends, L-shaped or Z-shaped layouts and industrial piping systems where the movement direction must be controlled.

The hinge assembly consists of hinge plates, pins and structural attachments that restrict the bellows to rotation about the hinge axis. The hinge hardware is also designed to restrain the pressure thrust generated by internal pressure acting on the effective area of the bellows.

A single unit primarily accommodates angular movement. When two or three hinged expansion joints are arranged as part of an engineered piping system, lateral thermal displacement in one plane can be converted into angular rotation at the individual joints.

Key Features

• Accommodates angular movement in one plane
• Hinge hardware controls the permitted direction of movement
• Structural hinges restrain internal pressure thrust
• Two- or three-joint arrangements can absorb lateral movement in one plane
• Suitable for L-shaped, Z-shaped and planar pipeline layouts
• Helps reduce thermal movement loads transferred to equipment connections
• Available with welded, flanged or project-specific connection ends
• Custom designs based on pressure, temperature, medium and rotation angle

Construction

A single hinged expansion joint generally consists of a metal bellows, pipe ends or connection flanges, hinge plates, pins, hinge lugs, a flow liner and any required reinforcing or limiting components.

The metal bellows accommodates angular rotation, while the hinge assembly controls the plane of movement and restrains pressure thrust. An internal flow liner may be added for high-velocity media, particle-laden flow or applications requiring a smoother flow path.

Material Options

Bellows can be manufactured from stainless steel grades such as 304, 316L and 321, or from other project-specified stainless steels and corrosion-resistant alloys.

Bellows material should be selected according to process-medium compatibility, operating temperature, design pressure and required fatigue life. Pipe ends, flanges, hinge plates, lugs and pins may be manufactured from carbon steel, stainless steel or other specified materials.

Movement Capability

A single hinged expansion joint permits rotation about its hinge axis and should not be treated as a conventional axial expansion joint. It is not intended to absorb unrestricted lateral movement as a single unit.

In a two- or three-hinge system, lateral pipeline displacement is converted into angular rotation at the individual joints. Actual movement capacity depends on the allowable rotation angle, distance between hinge centers, pipe length, piping geometry and support arrangement.

Pressure Thrust and Piping Supports

The hinge hardware restrains the pressure thrust generated by the bellows. However, the piping system must still account for bellows angular spring force, pipe and medium weight, dynamic loads, friction, wind, seismic forces and other external loads.

Suitable anchors, guides and load-bearing supports remain necessary to maintain the designed piping geometry and keep the expansion joints operating in the intended plane and within the allowable rotation range.

Typical Applications

• Industrial steam and high-temperature hot-water pipelines
• Petrochemical and chemical process piping
• Power, metallurgical and energy projects
• L-shaped, Z-shaped and planar pipeline layouts
• Equipment nozzles and heat-exchanger connections
• Piping systems requiring lateral movement in one plane

Installation and Design Requirements

• Align the hinge axis with the specified plane of rotation
• Verify face-to-face length, preset requirements and allowable rotation
• Maintain proper pipe alignment and avoid torsional loading on the bellows
• Do not force the joint into position to correct piping misalignment
• Do not use the joint to support unapproved pipe or equipment weight
• Provide anchors, guides and supports required by the piping design
• Remove or adjust shipping restraints according to the manufacturer's instructions

Information Required for Selection

Please provide the following information so that the joint structure and movement arrangement can be properly evaluated:

• Nominal diameter or pipe outside diameter
• Design pressure and operating pressure
• Design temperature and operating temperature
• Process medium and corrosion requirements
• Required angular rotation or lateral movement
• Number of joints and distance between hinge centers
• Piping layout, movement direction and installation position
• Weld-end dimensions, flange standard or other connection requirements
• Bellows, pipe-end and hinge-component material requirements
• Design cycle life, inspection, packaging and quantity requirements

We can design and manufacture single hinged expansion joints according to operating conditions, piping layouts and project drawings. Final construction, materials, pressure rating, rotation angle, movement capacity and inspection requirements are subject to the approved technical specification and manufacturing drawing.