RECTANGULAR
EXPANSION JOINTS

In addition to our core product range containing a wide selection of circular expansion joints, Belman also provides rectangular expansion joints.

Many design options
We design and manufacture rectangular expansion joints with single and multi-convolution bellows. These units can be made with no size limitation since they can be supplied in sections for transport and reassembly on-site.
Rectangular expansion joints can be designed to accept a combination of axial and lateral movement. When significant lateral movement is to be absorbed, a twin-bellows arrangement is usually required. Alternative corner arrangements can be supplied including single and double mitre and when necessary with rounded corners. Frames and bellows are available in a wide range of materials, sizes and configurations to suit individual customer requirements. These expansion joints are invariably used as customised solutions to expansion problems in rectangular ducting; they are purpose-designed and manufactured to match the customer’s unique requirements.

The rectangular expansion joints are customised solutions and are available in all dimensions, all sizes and all materials.

Large dimensions
If the rectangular expansion joints are large, they can be delivered in sections to ease transit and installation. The rectangular expansion joints can be supplied in segments of 2 or 4-sections with butt joints in the frames on the long sides of the unit. On installation the sections of the bellows and flow liner are fitted and welded into position by the installer. The rectangular expansion joints are fitted with shipping bars temporarily welded to the flange edges to protect the rectangular expansion joints, preventing damage during transit and assist with its handling into the final position at the jobsite.

Variety of materials
The bellows can be manufactured in a variety of materials (the same as for round expansion joints), including austenitic stainless steels (300 series), duplex, aluminium, titanium, and high-nickel alloys such as Inconel, Incoloy, Hastelloy and Monel.

Insulation of rectangular expansion joints
To withstand conditions that have a high internal temperature (e.g.1000°C) and low external temperature (e.g. 90°C), a special flow liner can be fitted (for example made from 1.4845). The liner is made with expansion gaps to enable it to expand at the operating temperature without generating unacceptable buckling at the hot face of the liner. As part of the installation, the void in the flow liner is filled with an insulation bolster comprising high-temperature insulating materials. This reduces the temperature across the insulation to provide a lower “skin” temperature, for example 90°C.

Additional options for rectangular expansion joints

• The intermediate pipe and the bellows can be supplied as one single piece
• Loose flanges
• Single mitre corner (90 degree corners) with the bellows being welded together in the corners