Expansion Joints - Type MFY | Macoga

Macoga MFY Hinged Expansion Joints

Macoga MFY are metallic expansion joints of the double hinged type with flanged ends. Construction includes two bellows, an intermediate pipe, and a dual hinge system. Designed to absorb lateral and angular movements in a single plane.

Operation and Load Management

The hinge assemblies absorb pressure thrust, eliminating the need for main anchors as required in unrestrained axial types. Pipe guiding remains necessary, but the number and strength of guides are reduced compared to simple axial expansion joints.

Permitted movements:

• Lateral: single plane only
• Angular: single plane only
• Axial: not a design function
• Multi-plane lateral/angular: not supported

Typical Applications

Used in steam, hot water, thermal oil, exhaust gas, and industrial gas lines where piping geometry allows movement in one plane and flanged connections are required for disassembly or replacement.

MFY vs MWY

• MFY: Double hinged, flanged ends.
• MWY: Same functional principle, but with weld ends.
• Both types feature two bellows, intermediate pipe, and hinge system to restrain pressure thrust.

Selection Criteria

Selection is based on pressure, temperature, nominal diameter (DN), flange type, rotation angle, lateral displacement, cycle life, bellows material, possible internal sleeve, and media compatibility.

Installation and Inspection

MFY joints are not intended for correcting misalignment. Check nameplate, flow direction (if internal sleeve is present), gaskets, guides, and ensure bellows are free from foreign objects. Protect bellows from impacts, scratches, arc strikes, and weld spatter.

Before pressure testing, remove yellow transport bars. For hydrostatic testing, use chloride-free water.