Concentric Reducer Rubber Flexible Joint with EPDM Inner Liner

The rubber expansion joint with rotating flange is usually also referred to as a rotating rubber joint or a single-ball rubber hinge connection. It is a special type of flexible connector for pipes. 

Its core feature is that it enables the pipeline to undergo angular deflection within a plane, and can also rotate around the axis of the joint, thereby absorbing the multi-directional displacements of the pipeline (mainly angular and torsional displacements), and reducing the installation stress.

A typical rotating flange-type rubber expansion joint is mainly composed of the following parts: 
Rubber sphere: The core component, usually made of natural rubber, EPDM rubber, chloroprene rubber, etc., is responsible for absorbing vibrations and displacements. 
Reinforcement layer: Within the spherical body, multiple layers of high-strength cord fabric or nylon cord are embedded, significantly enhancing the pressure-bearing capacity and strength of the joint. 
Flange: Metal flanges at both ends, used for connecting to the flanges of the piping system. 
Rotating ring/limiting pull rod: This is its most crucial feature. On both sides of the joint, there are usually 4 (or more) adjustable pull rods. These rods connect the two flanges together. The pull rods are equipped with nuts, allowing for adjustment of length and locking.

Working principle:
Angular displacement absorption: When two adjacent sections of the pipeline become misaligned due to thermal expansion and contraction, or foundation settlement, forming an angle, the flexible rubber sphere can undergo deformation to accommodate this angle change. Although ordinary rubber joints can also absorb a small amount of angular displacement, the amplitude is limited and they are prone to damage. 
Rotation and limit function: The rotating flange-type pull rod system plays a crucial role. 
Limit axial tension/compression: The length of the tension/compression rod is fixed, which can prevent the pipe from excessively elongating or compressing the joint under pressure or external force, thus protecting the joint from being damaged. 
Achieving controlled rotation: By adjusting the nut on one side of the lever while loosening the nut on the other side, it is possible to manually cause the entire joint to rotate slightly around its axis. This feature is extremely useful for precisely adjusting the final orientation of pipes or equipment (such as pumps, valves) during installation. 
Transmitting torque: In certain circumstances, it can transmit a limited amount of torque.

Application fields 
This type of joint is particularly suitable for the following complex working conditions: 
Pump inlet and outlet: This is the most common application. It can compensate for the huge thrust when the pump starts and the settlement of the pipeline, facilitating the installation and alignment of the pump. 
Near the valve: Absorbs the water hammer impact and pipeline stress generated during the opening and closing of the valve. 
Heat exchanger, cooling tower: Compensation device for thermal displacement between the equipment and the pipeline. 
Overhead pipes or pipes with uneven settlement: Adaptation to the uneven settlement of the foundation. 
Connections of equipment that require frequent maintenance or adjustment: By utilizing its rotating function, the position of the equipment can be conveniently moved or adjusted without the need to disassemble the entire joint.