Variations and optional devices for rubber expansion joints - Reduction Type | Macoga

MACOGA Reduction Type – Elastomeric Expansion Joint with Diameter Change

The MACOGA Reduction Type elastomeric expansion joint is specified when connecting pipelines of differing diameters. This configuration serves both as a compensator and as a reducer spool, eliminating the need for a separate metallic conical reducer.

Concentric and Eccentric Reduction

Two main geometries are available:

• Concentric reducer: Both pipe axes remain aligned. Used in vertical lines or horizontal runs where elevation consistency is not required.
• Eccentric reducer: Pipe axes are offset to maintain a consistent top of pipe or bottom of pipe. Typically selected for pump suction lines or systems where air or liquid entrapment must be avoided.

Selection Data

For technical selection, specify:

• Inlet and outlet DN (diameters)
• Reduction type: concentric or eccentric
• Flange standard: EN, ANSI, AWWA, JIS, or project-specific drilling
• Pressure, temperature, and conveyed medium
• Axial, lateral, and angular movement requirements
• Vacuum service, if applicable
• Elastomer material and optional PTFE/FEP internal lining

PTFE or FEP lining can be specified for wetted surfaces of the pipe and flange where enhanced chemical resistance is required.

Installation and Sealing

The joint must not be stretched, compressed, or twisted to compensate for misalignment unless designed for such movement. Pipe flanges should be flat, clean, and free of burrs. No additional gasket is installed between the elastomeric face and the pipe flange.

Applications

Commonly used in pump stations, cooling circuits, industrial water, desalination, chemical processes, HVAC, and piping systems with diameter transitions near equipment. No actuator is included; selection depends on geometry, pressure thrust, anchoring, media compatibility, and allowable loads at connections.