Expansion Joints - Type MFP | Macoga

Macoga MFP Hinged Expansion Joints

Macoga MFP are metallic expansion joints with a single bellows, equipped with hinged assemblies and flanged ends. The welded-end variant is designated MWP. The hinge system allows angular movement in a single plane and is not intended for axial or lateral displacement when used as a single unit.

Operation and Load Management

The hinge mechanism absorbs pressure thrust, eliminating the need for main anchors to counteract pressure forces, as required in unrestrained axial expansion joints. However, calculation and installation of pipe guides, intermediate anchors, and supports remain necessary to manage pipe weight, shear loads, wind, thermal movement, and vibration.

Permissible Movements

• Angular movement: Single plane only.
• Axial movement: Not permitted.
• Lateral movement: Not permitted as a single unit.
• Bellows torsion: Must be avoided.

Special versions with slotted hinges may allow limited axial movement, but in such cases, the hinge system does not absorb pressure thrust and appropriate anchoring is required.

Typical Applications

Used in steam, hot water, thermal oil, flue gas, and process gas piping where thermal expansion can be accommodated by angular movement. Two MFP/MWP or a double-hinged MFY/MWY can be installed in Z-shaped piping sections where movement occurs in a single plane.

MFP vs MWP

• MFP: Flanged ends, suitable where disassembly or replacement is required without pipe cutting.
• MWP: Welded ends, for permanent integration into the piping system.

Selection is based on DN, PN/class, flange standard, temperature, rotation angle, operating cycles, bellows material, optional internal sleeve, and media compatibility.

Installation and Inspection

MFP joints are not intended for misalignment correction. Verify flow direction (if internal sleeve is present), gasket selection, guide and anchor placement, and bellows cleanliness. Protect bellows from impact, scratches, arc strikes, and weld spatter. Remove yellow transport bars before pressure testing; for hydrostatic tests, use chloride-free water.