Frequently Asked Questions: Fabric & Metallic Expansion Joints

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Find answers to the questions about Expansion Joints and Fabric Expansion Joints. Expansion Joint is our passion and what we do everyday.

Here we have listed most of the common questions that our clients normally ask about Fabric Expansion Joints and Expansion Joints in generally. Following FAQs are guideline questions that clarify most of the common situations and questions that we have been asked frequently.

If you still can’t find the answers you are looking for, please leave us a message and we are glad to help you.

Fabric Expansion Joints


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In general fabric expansion joints are used in low pressure duct systems (<25000 Pa) – special designs can however be made accommodate elevated pressures/surge pressures

Multilayer fabric expansion joints consists of a sealing layer + a number of insulating/reinforcing layers. With the right composition of insulations layers a fabric expansion joint can resist up to 500°C and with the right insulation of the duct and use of insulation bolster a fabric expansion joint can resist up to 750°C. If the duct is refractory lined or equipped with internal cladding temperature resistance of up 1200°C can be achieved.

A fabric expansion joint is in general designed for either wet or dry use. However, some fabric expansion joints can depending on temperature work in both wet and dry applications.

 A fabric expansion joint can with the right design of steel parts resist high flow velocities (>100 m/s)

A fabric expansion joint is in general depending on the cooling on the outside, but the expansion joint can be insulated on the outside if the medium does not exceed the allowable temperature for the sealing layer.

A fabric expansion joint (or expansion joints in general) are to be considered as wearing parts that will need replacement after a certain a certain period of service. The lifetime is highly depending on the working condition and expansion joint construction. It is therefore not possible to give an exact figure of the expected lifetime.
Fabric will normally start showing signs of having reached the lifetime before actually failing and an experienced technician can normally from the appearance determine if the expansion joint need to be replaced at the next scheduled maintenance shut down.

A fabric expansion joint is often constructed with a sealing membrane, that has excellent resistance towards most known chemicals.

The steel parts needed for the fabric expansion joint will represent a certain value, but for replacement it is often only necessary to change the soft parts, which will be significantly less costly than changing the both fabric and steel parts.

In general a fabric expansion joint is working at low pressure and the reaction force generated from the pressure are minimal. Fabric expansion joints are normally considered to have no spring rates and the movements absorbed will there also not add forces to the pipeline.

Yes – depending on the weather conditions that the fabric expansion joint is subjected to a suitable outer cover that can be chosen to resist for example sunlight and rain.

Yes – as the fabric expansion joint often consists of build-up of several layers of insulation material, and it will resulted for certain noise reduction.

Belman Expansion Joints
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Expansion Joints
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Expansion joints are also known as expansion bellows, flexible joints, pipeline bellows, compensators, piping expansion joints and many more terms. No matter which term is used, the product is the same.

An expansion joint is a flexible component designed to absorb the dimensional changes of steel pipe systems and ducts. The changes could be heat-induced expansion and contraction, vibrations caused by rotating machinery or pressure deformations and misalignment during installation or building settlements.

Expansion joints are recognized as critical components of a complete pipe system. They are widely used in industries where thermal expansion in pipe systems occurs and in order to prolong the service life of pipe systems and reduce the risk of their downtime for additional maintenance and repair.


It is important to state that choosing the right bellows manufacturers makes the difference. Operational safety and reliable performance are crucial, irrespective of whether you will replace an existing expansion joint, install an improved expansion joint solution or if you plan to build a new plant/pipeline and introduce new expansion joints.  It may seem initially attractive to exclude expansion joints, but expansion joints offer so many options and advantages – which become clear once you know what are the advantages of using pipeline expansion joints.

The advantages include:

  • Simple in design and function
  • Space reduction
  • Weight reduction
  • Cost reduction
  • Reduce piping systems engineering requirements and design complexity
  • Improved flexibility for piping layout
  • Reliable and proven in the field
  • Further, expansion joints are more effective than alternatives such as pipe bends and pipe loops due to their greater ability to conserve space, their economic efficiency and better performance in absorbing larger movements.

Expansion joints come in a wide variety of types and designs, each delivers different benefits. Belman provides high quality Expansion Joints in a range from axial, lateral, angular, universal, FCCU, Pressure balanced, exhaust, vibration absorbers, elbow pressure balanced, crossover piping bellows, tank farm bellows, clamshell bellows, externally pressurized, ring reinforced, LNG/LPG, Scrubber expansion joints, lens, district heating, rectangular and hygienic expansion joints. Please visit Belman.com for more information. 

In most situations the expansion joint has to be customized – approximately 90% of all expansion joints sold are customized.

Belman designs and calculates all our high-tech expansion joints through the use of our in-house developed software BelMaker®, where all the latest design codes are implemented. Further, we use additional software such as: ANSYS, OHMTEC, Autodesk Inventor, Rohr2 etc. Finally, Belman designs according to all design codes such as: EJMA, ASME, EN or client specific design codes.


In many cases the origin of materials and the location of production of the expansion joints are important to clients. Belman’s state-of-the-art production facilities are located in Europe (with production facilities in Denmark and United Kingdom) as well as in India.


Expansion joint delivery can be organized by Belman to any site and/or client warehouse anywhere in the world. Being a global supplier Belman has a vast experience in finding the best and most cost-efficient method of delivery for your project. No matter if it is special transport, oversized transport, escorted transport, road freight, sea freight and/or air freight Belman can organize the transport on your behalf. Belman has formed close relationships with our transport partners. If the client wishes to arrange the transport themselves, Belman will gladly provide all information on the expansion joint and the required packaging.

Protected packaging

Expansion joints are always packed with suitable protection for the selected form of transport. For sea transport we can provide upon request sea worthy packing (ISPM 15). Belman is ready to comply with the specific packaging requirements of its clients.


Quality is an everyday priority at Belman, as of our reputation as a quality supplier, we will never compromise on quality of our products. We strive to provide expansion joints of the highest quality. Therefore, Belman considers test and quality procedures as a very important. To attest the level of quality and its capabilities Belman holds numerous certificates and type approvals.

Test & Inspection

Expansion joints can be subject to different tests and inspections. The scope of tests executed are determined by the requirements of the design code and/or the client’s specification. Belman executes some of the tests itself and some are performed by third parties. Belman is experienced in working with independent test authorities and clients are always welcome onsite for testing and final inspections. Belman provides all expansion joint non-destructive tests and can also on agreement provide destructive testing.

Welding & Material Control

Welding and material control at best in class metal bellows manufacturers are treated in the same way as Belman approaches quality. Our focus on quality also includes welding and within this area, we follow both client requests, project requests, our own quality procedures and the requirements of the design codes. All welding activity is carefully inspected under supervision of Belman’s welding inspectors (IWS and IWIS). Further, we have full traceability on all materials, including all filler materials. Full documentation is provided, on request, for all expansion joints – and as per client and project requirements. To ensure Belman’s short on-time delivery, we have an extensive stock of raw materials (plates, coils, flanges, pipes etc.). As quality is essential to Belman, we have a comprehensive control at goods reception in accordance with our QA procedures and policies.

The delivery time for Belman expansion joints is among the shortest on the market. Belman has an excellent reputation for short on-time delivery. In a recent customer satisfaction survey 98% of our clients confirmed that Belman met the stated delivery time. On-time delivery is especially important for you/your client to optimize the maintenance work/replacement work – you can rely on us to perform, without the risk of delayed delivery and unexpected costs.


Urgent delivery time?

Belman is known for being highly flexible on delivery times and in addition to standard on time deliveries our clients further benefit from our fast track services. With this, clients of Belman can get help – no matter if it is an unexpected shutdown, leaking expansion joint, part failures, an unexpected speed up etc. which demands an urgent delivery of the expansion joint. Many clients have already benefitted from the Belman fast track service; we can make the same service available to you.


Selected Fast Track Service references:

  • 7½ hours delivery time for a Swedish client (from order to delivery on-site)
  • Delivery of a customized double bellow DN 600 within 24 hours to Belgium (from order to dispatch)
  • 2 pcs. Expansion joints for a process plant in Malaysia completed in only 3 working days. The client received a daily progress report
  • Working around the clock on +60 expansion joints in order to minimize an unexpected shut down for a power plant
  • Slashing a 12 week lead time down to just 5 weeks for a nuclear power plant (incl. full documentation)
  • Reducing delivery time to 12 weeks on FCC units for an oil refinery. See the case story.

Correct installation is crucial to avoid unsafe and unreliable operation. When installed incorrectly the service life and pressure capacity of an expansion joint can be reduced and in worst case it will lead to a damaged expansion joint and/or pipe system, resulting in an unexpected shutdown. The installation guide from Belman describes how to ensure correct installation.

It is important to consider the following during the installation and handling of expansion joints:

  • Correct storage and transport
  • Correct removal of transport fittings / pretensioning fittings
  • Correct expansion installation in all stages
  • Understanding of flow direction
  • Correct placement of anchors/guides
  • Correct preparation and completion of pressure test
  • Correct expansion joint maintenance

You can find more information about these important points in the Belman Expansion joint installation guide, which is available in multiple languages.

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Please feel free to leave us a message and we will contact you as soon as possible. 

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Get in touch with a Belman Expansion Joint Specialist that can assist you with, 

  • One to one expansion joint replacement
  • New expansion joint project
  • Improvement of an existing expansion joint
  • Other expansion joint project requirements



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