Fabric Expansion Joints

What is a Fabric Expansion Joint?

Fabric Expansion Joints are advanced flexible components used in industrial ducting systems to absorb thermal expansion, mechanical displacements and vibration while maintaining mechanical integrity. Their flexibility, corrosion resistance, and adaptability to complex duct geometries make them indispensable in modern process industries.

These products are widely applied in flue gas handling, exhaust systems, pollution control, and process ventilation systems where temperature extremes, aggressive chemical environments, and demanding operational cycles are common.

Fabric expansion joints are custom-engineered to meet the specific movement, temperature, pressure, and chemical compatibility requirements of each application.

Primary functions and role in industrial systems

The key functions of fabric expansion joints include:

Absorbing thermal growth

Allowing duct sections to expand and contract under thermal loads without imposing significant loads on adjacent equipment.

Accommodating mechanical displacement

Managing lateral, axial, and angular misalignments caused by equipment settlement, thermal gradients, or seismic events.

Isolating vibration

Preventing vibration from rotating equipment (fans, blowers, compressors) from propagating through the duct system.

Reducing noise transmission

Acting as a passive noise-damping barrier.

Compensating for installation tolerances

Enabling easier system assembly even where ducts are not perfectly aligned.

Applications across industries

Fabric expansion joints are extensively used in sectors where thermal and mechanical movements must be accommodated in large duct systems:

Power Generation

Flue gas ducts, gas turbine exhaust, HRSG systems.

Cement and Lime

Preheater ducts, clinker coolers, bypass ducts.

Petrochemical and Refining

Process heaters, thermal oxidizers, reformer systems.

Steel and Metal Production

Blast furnace gas systems, electric arc furnace off-gas ducts.

Waste-to-Energy Plants

Incinerator exhaust ducts, gas cleaning systems.

Pulp and Paper

Recovery boiler ducts, lime kiln systems.

Marine and Offshore

Ship exhaust systems, offshore platform ventilation.

Air Pollution Control

Scrubbers, baghouses, ESP systems, wet and dry flue gas cleaning processes.

Key Benefits and Advantages

Fabric expansion joints provide distinct technical and economic advantages:

Multi-directional flexibility

Handles axial, lateral, and angular movements simultaneously.

Corrosion resistance

Excellent compatibility with acidic, alkaline, or chemically aggressive gas streams.

Lightweight design

Lower structural load compared to metallic joints.

High temperature capability

Withstands temperatures exceeding 1000°C when using advanced materials.

Vibration and noise isolation

Reduces mechanical stress and noise propagation.

Ease of installation and replacement

Flexible elements can be replaced without dismantling duct sections.

Design versatility

Custom configurations accommodate complex geometries and challenging operating conditions.

Design considerations and engineering process

Our expansion joints are designed and manufactured in accordance with:

Custom design

Duct size, geometry, and connection type
Gas composition, including chemical aggressiveness and particulate content
Movement profile – axial, lateral, angular, and combined displacements
Temperature and pressure profile, including thermal gradients
External conditions – weather, UV exposure, salt spray, and contaminants
Required service life and maintenance strategy

Advanced Engineering Tools

Finite Element Analysis (FEA) to predict stress and strain under combined loading
Thermal modeling to optimize insulation design and prevent thermal degradation
Material compatibility studies to ensure resistance to specific gas compositions

Multi-Layer Construction – Tailored for Performance

Fabric expansion joints are designed as multi-layered assemblies, with each layer serving a distinct function to ensure durability, flexibility, and gas-tightness under extreme conditions.

Outer Cover

Provides environmental protection against external factors such as weather, UV radiation, abrasion, and mechanical damage. This layer is crucial for the longevity of the expansion joint as it acts as a barrier against moisture, chemicals, and harsh environmental conditions. Common materials include silicone, Hypalon®, and PTFE, which offer excellent chemical and thermal resistance.

Gas Seal

Serves as the primary barrier to prevent gas leakage, ensuring airtight performance in applications where sealing is critical. This sealing layer is essential in systems that transport toxic, corrosive, or high-temperature gases. High-performance materials such as PTFE, Viton®, and fluoropolymer laminates are used to provide chemical and thermal stability across a wide range of temperatures and pressures.

Thermal Insulation

Minimizes heat transfer to the outer layers and reduces thermal losses in the system. This layer protects the outer materials from extreme heat and helps maintain energy efficiency. Common insulating materials include fiberglass, silica felt, and ceramic fiber, which can withstand high temperatures without degrading.

Reinforcement Layer

Provides mechanical strength and resistance to tearing, allowing the expansion joint to withstand mechanical stresses, vibrations, and system movements. Depending on the application requirements, materials such as aramid fabric, stainless steel mesh, and other high-strength fibers are used to achieve an optimal balance of flexibility and durability.

Internal Flow Liner

An optional layer designed to protect the expansion joint from high-velocity gas flows or abrasive particles. This liner is essential in systems with demanding flow conditions where erosion could affect the service life of the assembly. Common materials include carbon steel, stainless steel, and Inconel, depending on the required resistance to temperature and corrosion.

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