Fabric expansion joints

Expansion joint is one of the basic elements of pipelines and gas flues. Its task is to take over (absorb) and compensate movements of channels and pipelines resulting from thermal stress. Compensation also includes mechanical extensions, vibrations and reducing manufacturing errors such as piping misalignment. Single- and multi- layer expansion joints by KRAJ company are manufactured from glass, ceramic, silicate and aramid fabrics. What is more, expansion joints are also used with elastomers coated fabrics (e.g. EPDM, MVQ, FPM) and PTFE in production.


Insulating packages called thermal insulation pads are made of mineral wool for medium temperatures and ceramic or silicate mats at high temperatures. In the case of the abrasion mediums, the protection and insulation is obtained by using guide plates. These sheets are made of ordinary steel or antiabrasion steels for the most demanding applications. The use of high quality materials and their correct selection makes our compensators resistant to a wide range of media – from abrasives to highly aggressive mediums


Expansion joint – inserted between the different parts of piping in order to remove the pressure caused by thermal expansion.

Our products are characterized by:

  • maximum temperature of medium: 1000°C
  • maximum pressure of 3 bar
  • high chemical and mechanical resistance
  • high resistance to abrasive media
  • the possibility of transferring large displacements in all directions

The scope of work KRAJ Company:

  • measurements on objects
  • design
  • production of soft and steel parts
  • assembly and / or supervision on installation
  • warranty and post-warranty service

Expansion joint’s sleeve in most cases is multilayered. The exceptions are the applications requiring high chemical resistance or simple ventilation systems. The individual layers of expansion joint perform different functions and complement each other (support layers, stability, insulation, sealing). Expansion joints manufactured by KRAJ Company do not contain asbestos. The following list of materials is used in production:

Basic types of fabric expansion joints:

  • Tubular fabric expansion joints KRAJ® KR-KR
  • Flange fabric expansion joints KRAJ® KR-KK
  • Fabric expansion joints pleated at connection buck KRAJ® KR-KHR
  • Fabric expansion joints pleated at connection flange KRAJ® KR-KHK
  • Flange-tubular fabric expansion joints KRAJ® KR-KHK

Basic types of guide plates:

  • A single sheet welded to one end of the channel, or as a part of one;
  • Double sheet welded to both sides;
  • A single plate welded to one end of the channel (part of a cone or a pyramid);
  • Guide plate with so-called floating ring;
  • Guide plate bolted to the channel together with the fabric part;

What is more, fabric expansion joints can be made as a joiner of two different dimensions, from large diameter to small channels, or different geometrically – joining of ducts with rectangular cross section with the circular channel.

Material, shape and type of a guide are closely related to operating parameters of the expansion joint, also to the movements which have to be compensated.