Expansion Joints

Expansion joints are high-quality products which are used in industrial equipment, plant units, machinery and pipelines. They have been proving their worth for many years in power engineering, HVAC, the waste incineration/disposal industry, the cement and steel industry and the chemicals industry, as well as in materials handling and the ceramic industry.

All exhaust gas duct work requires expansion joints or vibration eliminators to absorb any movement in duct work. Otherwise referred to as bellows, specialised solutions for chemical expansion and duct work also include thermal covers.
We manufacture a range of fabric and metallic expansion joints. The correct materials are selected depending on temperature and the type of corrosive gases present.

We supply fabric expansion joints made from high temperature fabrics and are also able to incorporate high density noise barrier materials to provide a sound barrier in joints on or near fans.

We offer a complete service including design, manufacture and supply of the fabric and metallic expansion and associated steel work.

Expansion Joint

Expansion Joint

Technical data

Movements in expansion joints

Axial compression
The dimensional shortening of the expansion joint face-to-face gap parallel to its longitudinal axis. 

Axial extension
The dimensional lengthening of the expansion joint face-to-face gap parallel to its longitudinal axis. 

The dimensional displacement of the inlet and the outlet flanges of the expansion joint perpendicular to its longitudinal axis.

Torsional rotation
The twisting of one (1) end of the expansion joint with respect to the other end about its longitudinal axis. 

Angular rotation
That movement which occurs when one flange of the expansion joint is moved to an out-ot ­parallel position with the opposite flange.

Document downloads

Document title Document type Document language
expansion-joint-order-form-submit English
Offshore Marine Brochure English
Offshore Marine (ZH) Brochure 中文 (Chinese)
Pyrotek LNG & Offshore Catalogue Catalogues English
Pyrotek LNG & Offshore Catalogue (ZH) Catalogues 中文 (Chinese)


  • Custom-made metallic bellows for high temperature, pressure and chemical resistance
  • High noise reduction acoustic expansion joints


  • Fabric expansion joints custom designed and fabricated
  • Variety of specialty fabrics to withstand highly corrosive, acidic and alkaline conditions
  • Complete expansion joint assemblies ready for installation
  • On-site supervision of installation


Expansion joints profiles

Fig. 1. Single flow liner 
In positive flue gas systems with flush mount composite designs, bottles are recommended to extend the life of the expansion joint. In negative systems, a single flow liner is used to prevent the joint from being pulled into the flow causing the joint to fail prematurely from flutter and erosion.


Fig. 2. 'U' design - integrally flange type
This expansion joint profile incorporates its own flanges which are perpendicular to the plane of the duct. 


Fig. 3. Double flow liner
The double flow liner is used in systems with large duct movements and elevated temperatures.


Fig. 4. Belt type
This expansion joint profile is mounted parallel to the plane of the duct.


Fig. 5. Insulation pillow
An insulation pillow is recommended for all composite joints continuously operating at temperatures 800 degrees F (426 degrees C) and above. The insulation pillow keeps belt temperatures down and increases the service life of the joint. The pillow consists of fiberglass or ceramic fiber (determined by flue gas temperature) encased in high temperature fabric and/or stainless steel mesh. An insulation pillow is also supplied in heavy fly ash environments to prevent ash buildup between the flow liner and the expansion joint.


Fig. 6  Belt type with single flow liner
This type permits the gas to be cooled protecting the expansion joint.


 Fig. 7. U type with single flow liner
The flow liner prolongs the life of the expansion joint where gases contain abrasive dust.


 Fig 8. Belt type with single flow liner
This type permits the gas to be cooled protecting the expansion joint. The design has the expansion joint frame independent of the duct frame.



type of expansion joints

type of expansion joints