Expansion Joints - Type MWP | Macoga

Macoga MWP Hinged Expansion Joints

The Macoga MWP series are metallic expansion joints with a single bellows, welded ends, and a hinged system. The corresponding flanged version is designated MFP. The hinge mechanism allows angular movement in a single plane and is not intended for axial or multi-plane lateral displacement.

Operation in Piping Systems

The hinge assembly is engineered to absorb pressure thrust, eliminating the need for main anchors to counteract pressure forces, unlike unrestrained axial types. However, calculation and installation of guides, intermediate supports, and anchors remain necessary to accommodate pipe weight, thermal movement, wind/shear loads, and operational vibration.

Typical Applications

Commonly used in piping systems where thermal expansion is redirected as angular movement:

• Steam, hot water, and thermal oil lines
• Industrial process piping
• Z-shaped pipe sections in a single plane
• Pipelines with angles other than 90°
• Paired MWP/MFP or alternatively a double-hinged MWY/MFY for planar expansion absorption

Selection Criteria

Selection should verify DN, design pressure, temperature, rotation angle, cycle life, bellows material, weld ends, possible internal sleeve, and media compatibility. Slotted hinge variants permit limited axial movement but do not absorb pressure thrust, requiring suitable anchoring.

Installation and Inspection

MWP joints are not intended for misalignment correction. Protect bellows from impact, scoring, arc strikes, and weld spatter. Do not suspend by hinges or shipping bars. Remove yellow shipping bars before pressure testing; use chloride-free water for hydrostatic tests.

FAQ

Does it absorb axial expansion?
Not in standard operation. It is a hinged device for angular movement in one plane.

Is an actuator required?
No. It operates passively, responding to pipe movement.