Expansion Joints - Type MPBE Elbow pressure balanced | Macoga

Macoga MPBE Elbow Pressure Balanced Expansion Joints

Macoga MPBE units are metallic pressure balanced elbow expansion joints designed for installation at pipeline direction changes. The assembly absorbs axial and/or lateral movements while simultaneously balancing the thrust force generated by internal pressure.

Operating Principle

The design incorporates a main line bellows and an additional balancing bellows, both exposed to the same pressure. Pressure forces act in opposite directions and are mechanically linked via tie rods, ensuring that pressure thrust is contained within the joint assembly.

MPBE joints can be installed between intermediate fixed points without the need for main anchors to absorb pressure thrust. Loads transmitted to adjacent equipment are limited to the bellows movement forces.

Permissible Movements

• Axial movement
• Lateral movement in one or more planes
• Angular movement in a single plane
• Multi-plane angular movement (limited use only)

Typical Applications

Used in steam, hot water, thermal oil, process gas lines, and connections to turbines or sensitive equipment where nozzle loads from internal pressure thrust must be avoided. Technical documentation includes standard arrangements with axial guides, intermediate anchors, and turbine connections.

MPBE vs MPBI

• MPBE: for elbow installations or direction changes.
• MPBI: inline pressure balanced for straight runs.
• Both types are specified when expansion must be absorbed without transferring pressure thrust to adjacent equipment.

Installation and Inspection

Not intended for misalignment correction. Prior to installation, verify nameplate data, flow direction (with internal sleeve), gaskets, anchors, guides, and bellows cleanliness. Transport bars (yellow) must be removed only after final support and before pressure testing. Hydraulic tests require chloride-free water.