Gallery Guides & Technical Articles

Why Modern Airport Architecture Relies on Expansion Joint Technology

February 4, 2026

Secure your piping against the forces of thermal expansion, and boost operations with single expansion joints from US Bellows.

Modern airport terminals are breathtaking examples of engineering, often featuring expansive glass curtain walls and soaring steel skeletons. However, these massive structures are constantly in motion. As the sun beats down on a terminal’s exterior, the materials expand; as temperatures drop overnight, they contract. Without a sophisticated system of expansion joints, these natural movements would result in shattered glass, cracked components, and compromised structural integrity.

Designing for Aesthetics and Mechanical Stability

In a large-scale terminal, the architectural beauty must be matched by mechanical resilience. The HVAC and plumbing systems running through these buildings are often rigid, yet they are anchored to a frame that is designed to flex. Expansion joints serve as the essential interface between these two worlds, allowing the building to breathe without putting undue stress on the life-safety and comfort systems that passengers rely on.

Protecting Fragile Glass and Facade Systems

When a terminal spans hundreds of thousands of square feet, the cumulative effect of thermal expansion can extend a pipeline by several inches. Expansion joints integrated into the piping and ductwork ensure that this movement isn’t transferred to the building’s facade. By absorbing these shifts, expansion joints prevent the massive thermal forces from damaging the building’s facade.

Ensuring Uninterrupted Passenger Comfort

Passenger comfort is a top priority for airport operators, and this depends entirely on the health of the HVAC system. Expansion joints installed at key intervals and equipment headers act as shock absorbers, helping with flexibility and isolating mechanical equipment from piping movement. This means passengers can enjoy their time in the terminal, whether cooling or heating is needed.

Managing Extreme Temperature Differentials

Airports are unique because they maintain a strict climate-controlled interior while being exposed to extreme outdoor runway temperatures. This creates a significant thermal gradient across the building’s envelope. Engineered expansion joints are designed to accommodate these differentials, ensuring that even when the tarmac is radiating heat, the internal piping remains stable and leak-free, keeping the terminal cool and the passengers comfortable.

To help airport facility managers and MEP engineers select the right components, the following table outlines the technical differences between metallic and fabric expansion joints. Each material serves a specific purpose based on the terminal location and the media being transported.

Comparison of Expansion Joint Materials for Airport Infrastructure

Feature	Metallic Bellows	Fabric Expansion Joints
Primary Use Case	High-pressure steam, fuel lines (Jet A-1), and chilled water loops.	Low-pressure HVAC ducting, air handling units, and ventilation.
Movement Capability	Good for axial, lateral, and angular movement in high-pressure systems.	Superior for large amounts of concurrent movement in multiple directions.
Pressure Rating	Can handle extreme pressures (from vacuum up to 1,000+ PSI).	Strictly for low-pressure or atmospheric systems (typically < 5 PSI).
Vibration Isolation	Good, but often requires specific engineering to dampen high-frequency noise.	Exceptional; the non-rigid material naturally absorbs almost all mechanical vibration.
Space Constraints	Compact design; Single EJs are ideal for tight utility tunnels and ceiling plenums.	Compact. Design must allow the fabric to flex without tearing. Can accomplish larger movements than metal in the same face-to-face length.
Durability	Highly resistant to external corrosion when coated, galvanized, or made of stainless steel.	Vulnerable to sharp objects or high-velocity particulate if not lined.

Which One Does Your Terminal Need?

Protect modern airport infrastructure with expansion joints from US Bellows.

Choosing the wrong material can lead to premature failure and expensive terminal repairs. US Bellows can perform a system-wide review to ensure your specifications match the unique demands of your airport’s mechanical design.

Selecting the right expansion joint depends on the specific zone of the airport:

The Utility Tunnel: These areas almost exclusively require metallic bellows. Because they carry high-pressure steam for heating or de-icing, the material must withstand significant forces and accommodate the large thermal expansion over long distances.
The Concourse HVAC: For the air distribution systems that keep passengers comfortable, fabric expansion joints are often the better choice. They are cost-effective, easy to install in ductwork, and eliminate the “rattle” that can occur when heavy air-handling units cycle on and off.
The Tarmac Fueling System: This is a mission-critical environment; only metallic joints that have undergone rigorous testing (e.g., those provided by US Bellows) should be used. These joints must withstand the chemical properties of aviation fuel and the physical loads imposed by overhead ground support equipment.

Airport Expansion Joint Engineering FAQ

How do expansion joints contribute to the acoustics of an airport terminal? Expansion joints do more than just manage movement; they also act as vibration isolators. By breaking the metal-to-metal contact in piping and ductwork, they prevent the “hum” of mechanical rooms from traveling through the terminal walls, contributing to a quieter, more pleasant environment for travelers.

Are expansion joints required for airport fire sprinkler systems? Absolutely. Because fire protection lines run the entire length of the terminal, they are subject to the same thermal and seismic stresses as any other pipe. Expansion joints ensure these lines remain intact and pressurized, even if the building shifts during a seismic event or extreme weather.

How often should expansion joints in terminal ceilings be inspected? While many joints are designed for a long service life, we recommend a visual inspection every 2 to 5 years. This is especially important in terminals located in regions with high seasonal temperature swings, as the bellows undergo more frequent cycles of expansion and contraction.

Build for Longevity in Terminal Design, Not Just Aesthetics

Don’t let thermal stress compromise your architectural vision or passenger experience. Book a meeting with our engineering team at US Bellows to see how our custom-engineered expansion joints can add decades of reliability to your next terminal project.

The Engineering Guide to Selecting Expansion Joints for Dielectric Fluid Loops

January 28, 2026

Discover how material selection in expansion joints is an important procurement detail and a strategy for long-term reliability.

As data centers pivot toward direct-to-chip (DTC) and immersion cooling to handle the heat of next-gen GPUs, the data center “plumbing” is being pushed to its physical limits. Data center operators are moving away from simple chilled-water systems toward specialized dielectric-fluid and treated-water loops.

In this environment, the choice of expansion joint material is both an important procurement detail and a strategy for long-term viability. While rubber expansion joints may survive a standard office HVAC system, critical high-performance computing (HPC) loops require the chemical resistance of 300-series stainless steel or Inconel.

Navigating the Chemistry of Modern Cooling Fluids

The shift to liquid cooling introduces a complex variable: chemical compatibility. Whether you use propylene glycol blends or specialized immersion oils, the elastomers in traditional gaskets and rubber joints can degrade, leach, or become brittle over time.

The Case for 300-Series Stainless and Inconel

Metallic bellows, specifically those engineered from Type 304 or 316L stainless steel, provide an inert surface that won’t react with modern coolants. In ultra-aggressive environments or systems where chloride-induced stress-corrosion cracking is a risk, Inconel 625 provides even greater protection. These materials ensure that no particulates enter the loop stream due to corrosion or degradation—a necessity when the cooling channels on a cold plate are measured in microns.

Engineering for the Infinite Loop: Fatigue and Cycle Life

In an HPC environment, thermal loads are non-stationary. As workloads spike during AI training runs and drop during idle periods, the piping system undergoes constant thermal expansion and contraction. This is where cycle life becomes the most important metric you’ve never heard of.

Mastering the Thermal Pulse

Unlike rigid piping, a metallic expansion joint is engineered as a flexible pressure vessel. Each convolution in the bellows is designed to evenly distribute stress, while containing the pressure of the line. By using the design temperature to estimate the line’s movements and the frequency of power cycles, our engineers can design a bellows with a rated cycle life in the tens of thousands. This prevents fatigue cracking: the microscopic failure of the metal grain structure, and ensures that the joint lasts as long as the data center itself, not just the current server generation.

FAQ: Critical Insights for Liquid Cooling Infrastructure

How does dielectric fluid creep affect expansion joint seal selection?

A: Dielectric fluids have lower surface tension than water, making them prone to creep through standard gaskets. Effective designs use convoluted metallic bellows with welded ends rather than flanged mechanical joints to ensure a zero-leakage environment.

Can metallic expansion joints be used in two-phase immersion cooling?

A: Yes. Because metallic bellows are hermetically sealed and are resistant to the high pressures and vapor phases of dielectric fluids (especially 316L), they are the preferred choice for sealing the integrity of two-phase cooling loops.

What is the typical lifespan of an Inconel-625 bellows in an HPC loop?

A: When properly engineered for the system’s thermal movements, an Inconel-625 bellows is often rated for a design life of 20+ years, far outlasting the 3–5 year refresh cycle of the IT equipment it cools.

Make sure your cooling infrastructure is ready for the next generation of power density.

Transitioning to direct-to-chip or immersion cooling is a complex leap, but your piping doesn’t have to be a source of stress. We help engineers bridge the gap between traditional HVAC and modern HPC reliability.

Let’s discuss your project’s unique requirements and find the exact bellows solution to keep your uptime at 100%. Contact our engineering team for a comprehensive review of your piping stress analysis and material compatibility requirements.

Hinged Expansion Joints Custom-Designed for a Process that Produces High-Density Polyethylene (HDPE)

January 20, 2026

U.S. Bellows custom designed these hinged expansion joints for a Polyolefin process which produces High-Density Polyethylene (HDPE) resin at a chemical plant. Polyolefins are a family of polyethylene and polypropylene thermoplastics. The job included expansion joints ranging from 12″ to 32″ NPS. The units pictured above have a nominal pipe size of 16″. The bellows and liner were fabricated from 304 stainless steel and the flanges, cover, and hardware from carbon steel. They are designed for an operating temperature of 176°F at 145 psig and 1° of angular movement. The expansion joints were 100% dye penetrant tested, the bellows longitudinal seam welds were 100% X-rayed, PMI examined, and hydro-tested prior to shipment.

Preventing Unplanned Coke Drum Outages: An Integrated Approach to Piping Flexibility

January 13, 2026

Top view male worker inspection at steel long pipes and pipe elbow in station oil factory during refinery valve of visual check record pipeline oil and gas

In this environment, the greatest threat to uptime isn’t just the heat; it’s the mechanical stress it causes. Without a sophisticated approach to piping flexibility, the assets that drive refinery margins become the greatest liabilities.

The Danger of Stiff Piping on Critical Assets

When piping is too rigid, thermal expansion has nowhere to go. This force is transferred directly to the unit’s most expensive equipment: the coke drums.

Excessive nozzle loads caused by stiff piping lead to:

Drum Shell Cracking: Repeated stress at the nozzle-to-shell interface can lead to fatigue and catastrophic failure.
Leakage: Thermal growth can pry open bolted connections, leading to hazardous leaks and fire risks.
Support Failure: Rigid systems can buckle steel structures or crush pipe shoes as they try to expand.

To protect the drum, engineers must design a system that “breathes.”

The Solution: Engineered Flexibility and PSA Validation

Managing these loads requires a strategic combination of pipe stress analysis (PSA) and custom-engineered expansion joints. Using advanced software such as CAESAR II, engineers can model the exact displacement of the piping system at every phase of the coking cycle.

The Role of Specialized Expansion Joints

In the tight footprints of a Coker unit, there often isn’t enough room for large pipe loops. This is where specialized hardware becomes essential:

Gimbal and Hinged Expansion Joints: These units allow for angular rotation in any plane while containing pressure thrust. They are ideal for absorbing multi-planar movement in overhead vapor lines.
Refractory-Lined Joints: Specifically designed for the feed lines, these joints handle abrasive catalyst fines and extreme temperatures simultaneously.

By integrating PSA data into the hardware design, US Bellows can manufacture joints with convolution profiles specifically calculated to survive the predicted cycle life of the Coker unit.

Although refineries are not limited to delayed coking units, they may use fluid coking and flexicoking processes, but the end result is the same: producing petroleum coke.

The Power of One: The Piping Technology and US Bellows Combined Value Proposition

In critical midstream and refining projects, failures occur at the interface between a pipe hanger and a bellows. The combined expertise of Piping Technology & Products (PT&P) and US Bellows eliminates this gap.

We provide a single-source solution where the pipe supports (PT&P) and the expansion joints (US Bellows) are engineered in tandem. This ensures that every variable, from variable spring hanger settings to bellows spring rates, is synchronized within your stress model. The result is a unified system that reduces nozzle loads, extends equipment life, and simplifies project management.

Strategic Engineering FAQ: Coker Units & Thermal Stress

Q: Why is pipe stress analysis (PSA) critical for coker expansion joint design?

A: PSA determines the cold spring requirements and the hot position of the piping. Without this data, an expansion joint might be installed in a way that exhausts its movement capacity before the unit even reaches operating temperature, leading to immediate bellows failure.

Q: How does quenching affect expansion joint metallurgy?

A: Quenching is the rapid-cooling of metal. It normally uses water or air as the medium to alter the metal’s structure, locking in a hard, strong microstructure and increasing hardness. However, during plant operation, rapid cooling during the quench cycle can cause thermal shock and brittleness. We utilize high-nickel alloys and specific heat-treatment processes to ensure the bellows material can withstand the “fatigue cycles” inherent to the coking process without stress-corrosion cracking.

Q: Can expansion joints reduce the frequency of coke drum inspections?

A: Yes. By using expansion joints to keep nozzle loads well within ASME B31.3 or Section VIII limits, you reduce mechanical fatigue on the drum shell, enabling optimized inspection intervals and lower maintenance costs.

De-Risk Your Next Turnaround with PT&P and US Bellows

Don’t leave your coker drum integrity to chance. We can help you troubleshoot a chronic leak or design a new transfer line. Our team of stress analysts and bellows engineers is ready to help.

Contact the US Bellows Engineering Team to explore our expansion joint solutions for coker units.

Custom Single Ply X-Flex Bellows Designed for a Manufacturing Company of Flooring Products

December 31, 2025

U.S. Bellows designed and manufactured customized single-ply X-Flex® bellows for the world’s largest manufacturer and supplier of flooring products, with facilities located throughout the United States. Flooring products—including carpet, ceramic tile, natural stone, laminate, vinyl, and hardwood—require many of the same piping systems found in traditional industrial plants such as automotive, food processing, semiconductor, textile, and pulp and paper facilities.

Flooring manufacturing plants are typically very large, often spanning extensive tracts of land. As a result, pipe runs can extend hundreds of feet, necessitating the use of expansion joints to accommodate thermal movement and relieve stresses within the piping systems.

Externally pressurized expansion joints are particularly well suited for applications requiring large amounts of axial compression or extension. In these designs, the bellows elements are configured so that the process media flows along the external surface of the bellows. This external pressurization eliminates pressure instability as a design limitation and allows for the absorption of significant axial movement.

For this application, the expansion joints were fabricated with 304 stainless steel bellows, flanges, and pipe. The units were designed for operating temperatures up to 300°F at ±14.7 psig (full vacuum) and were capable of accommodating up to 8 inches of axial movement. The assemblies included 3-inch pipe by 40-inch-long units and 4-inch pipe by 40-inch-long units.

All expansion joints were hydrostatically tested and subjected to non-destructive examination (NDE) quality control inspections, including liquid penetrant examination (LPE), prior to shipment to ensure compliance with performance and quality requirements.

Refinery Reliability: The Critical Role of Expansion Joints in FCCU

Petroleum oil and gas industry

In a modern oil refinery, the fluid catalytic cracking unit (FCCU) serves as the primary engine of production. These units convert heavy crude into high-value products like gasoline and diesel, but they operate under punishing mechanical conditions. With process temperatures frequently reaching 1400∘F (760∘C) and the constant movement of abrasive catalysts, the piping system is under a heavy strain.

The essential components that manage this volatility are high-temperature refractory-lined metal expansion joints. Without these precision-engineered parts, the thermal expansion of massive steel piping would generate forces powerful enough to buckle structural supports, crush turbine nozzles, and trigger catastrophic system breaches.

Engineering for Extreme Heat: Why FCCUs Demand Specialized Joints

US Bellows offers custom-engineered expansion joints for FCCU Refinery piping is a dynamic system. In an FCCU, the transition from ambient temperature to whole operation can cause a 100-foot-long pipe to expand by nearly 12 inches. If rigid connections constrain this movement, the resulting stress will concentrate at the weakest point—typically a weld or a critical component of rotating equipment.

The largest and most critical expansion joints, often refractory-lined, manage significant thermal growth between the massive vessels, between the reactor and the separator/regenerator, and are primarily installed in the overhead line of the FCC Unit.

Expansion joints are also used on the Power Recovery Train (PRT) Connections to handle thermal and dynamic movements, as well as the transfer Lines between equipment and flue gas lines.

The flue gas lines are among the most punishing service environments a component can encounter. These lines transport abrasive catalyst fines and scorching exhaust at high velocities, creating a constant battle against thermal expansion and vibration. Because FCCU flue gas lines operate at extreme temperatures, often exceeding 1200°F, the expansion joints must be engineered with specialized refractory linings and multi-ply bellows to withstand both internal erosion and external stress.

A failure here doesn’t just mean a leak—it can lead to a complete unit shutdown, making the precision of US Bellows engineering and historical design insights essential for maintaining continuous operation in these critical paths.

The Challenge of Catalyst Abrasion

In FCC units, expansion joints must withstand not only heat but also “fluidized” catalysts that act as abrasive media. To combat this internal wear, engineers utilize refractory-lined expansion joints. These “Cold Wall” designs employ internal insulation to keep the outer shell temperature below 650∘F (343∘C). This allows the use of carbon steel for the main piping while isolating the bellows from erosion and extreme thermal degradation.

Managing Pressure Thrust in FCC Units

FCC units undergo cyclic temperature swings, leading to “pipe walking” and intense pressure thrust. Tied Universals, or a hinge/gimbal arrangement, are vital in these configurations. They use constraints to constrain the pressure forces, ensuring that the refinery’s anchors and equipment nozzles are not overloaded by internal system pressure during cycles.

Refinery Engineering Insights: FCCU Expansion Joint FAQ

Q.Why do the FCCU industry (designers/owners) prefer a “Cold Wall” design for both piping and expansion joints?

A. FCCU systems often transport catalysts at temperatures that exceed the allowable stress limits of standard piping materials. A “Cold Wall” design uses an internal refractory lining to lower the shell’s skin temperature, protecting the structural integrity of the pipe. In contrast, the internal flow remains at extreme process temperatures.

FCC units use cold wall designs over hot wall designs primarily for better reliability, easier maintenance, lower metallurgy costs, and reduced thermal stress on components like expansion joints, as cold walls use internal refractory to keep the outer shell cooler (e.g., below 650°F), preventing high-temperature issues like creep and sulfidation seen in hot wall designs where the shell operates near media temperatures. Hot walls are simpler but suffer from significant expansion issues and costly, time-consuming repairs, while cold walls offer better control and a longer lifespan for high-temperature transfer lines.

Q. How does a 2-ply testable bellows prevent refinery downtime?

A. In a 2-ply design, each layer is engineered to handle the full pressure of the system. By installing a pressure gauge or “sniffer” between the plies, operators can detect a leak in the inner layer immediately. This provides a safety buffer, allowing the unit to continue running safely until the next scheduled turnaround.

Q. What materials are best for high-temperature refinery expansion joints?

A. Standard stainless steels often fail due to creep or corrosion at refinery temperatures. We typically use high-nickel alloys such as Inconel 625LCF for its superior fatigue resistance and high-temperature strength, or Incoloy 800/H/HT for its excellent resistance to high temperatures, carburization, and chloride-stress cracking, and 304H/321H stainless steel for applications requiring high-carbon stability.

The US Bellows Advantage: Engineering for 24/7 Refinery Performance

Off-the-shelf components cannot survive the specific “hot wall” or “cold wall” requirements of a modern refinery. At US Bellows, we specialize in custom-engineered solutions that prioritize mechanical safety and long-term cycle life.

Our Value Proposition:

US Bellows delivers refinery-grade expansion joints engineered with advanced alloys (Inconel 625LCF, 304H/321H) and specialized refractory systems that eliminate thermal fatigue and catalyst erosion, backed by 24/7 emergency field services to ensure your FCCU maintains peak uptime.

Key Features of Our Refinery Solutions:

Multi-Ply Testable Bellows: We offer redundant-ply designs featuring active monitoring ports. If the inner ply reaches its wear limit, the outer ply maintains the pressure boundary, allowing for a planned maintenance window rather than an unscheduled shutdown.
Custom Refractory Integration: Our designs account for the added stiffness of refractory linings, ensuring accurate stress analysis and predictable movement absorption.
EJMA-Compliant Design: Every unit is designed according to the Expansion Joint Manufacturers Association (EJMA) standards, ensuring it can handle the specific axial, lateral, and angular movements unique to your facility.

Protect your refinery’s most critical assets by partnering with US Bellows for your next FCCU turnaround. Connect with our engineering team for a custom pipe stress analysis and project quote.

Protecting Industrial Ductwork: Fabric vs. Rubber Expansion Joints

December 22, 2025

Man wearing hard hat and safety vest inspects hvac system in industrial building. worker monitors ductwork and pipes in commercial facility. engineer oversees infrastructure in large office building.

Industrial Expansion Joints Explained: Fabric, Rubber, and Essential Accessories

Industrial ductwork in power generation and chemical processing faces three main challenges: thermal expansion, vibration, and misalignment.

The solution to preventing leaks and structural damage is the use of engineered fabric and rubber expansion joints. Think of expansion joints as the shock absorbers of your industrial piping; without them, every bump in temperature or pressure rattles the entire frame until something breaks.

This guide explores the differences between fabric and rubber expansion joints, as well as the essential accessories required to build a resilient system.

Fabric vs. Rubber Expansion Joints: Which Is Right for You?

Selecting the correct expansion joint depends heavily on the specific environmental factors of your operation, such as temperature, pressure, and the presence of corrosive elements.

When to Choose Fabric Expansion Joints

Fabric expansion joints are engineered for flexibility and high-heat environments. They are the best choice for:

High-Temperature Applications: They excel in environments like flue gas ducts, and fabric joints can be insulated for extreme temperatures
Low-Pressure Systems: Best suited for applications where pressure is not the primary stressor. In general, fabrics are limited to +/- 100” of water column.
Complex Movements: These joints can handle significant multi-plane movements, including axial, lateral, and angular shifts, all in a relatively short span of length in the ductwork
Minimize Reactive Forces: Fabric joints are lightweight, exerting minimal reactive forces on equipment and making them ideal for large-diameter ductwork and exhaust applications.
Maintenance: Because it is lightweight, fabric joints can be easily maintained and replaced. One can only replace the fabric, not the entire frame of the expansion joint.
Corrosive Environments: Fabric joints offer high resistance to corrosive gases and harsh chemicals, especially PTFE Fabrics

Considerations

Leak-tight Applications: While many fabrics can be leak-tight, you will see leakage at fabric attachments to your ductwork, whether via clamps, retaining bars, or bolts.

When to Choose Rubber Expansion Joints

Rubber Expansion Joints for Centrifuge Suction & Discharge of Paraxylene Application Rubber expansion joints are the industry standard for liquid handling and vibration control. They are ideal for:

Vibration-Heavy Systems: Excellent at vibration dampening and noise reduction.
Liquid Systems: specifically designed for pumping systems, chillers, and water/wastewater treatment plants.
Moderate Corrosion Resistance: Rubber offers good sealing and water resistance. Specific rubber compounds are key for common chemicals, weathering, and UV.
Longevity: In the right environment, rubber joints are long-lasting and maintenance-free.

Considerations

Extreme temperatures (High Temps or Cryogenic): Rubber joints are not meant to handle high temperatures. In these situations, consider metal or fabric. By the same token, at cryogenic temperatures, rubber is brittle and not recommended.
High Pressure: Rubber joints can withstand up to 300 psi, depending on the diameter; for larger diameters, the pressure rating decreases. Metal joints need to be considered for high pressures.

Common Questions: Essential Expansion Joint Accessories

An expansion joint is only as effective as the system it is part of. To get the best performance and safety, engineers should integrate specific accessories to protect the infrastructure from heat, erosion, and stress.

What is the function of flow liners?

Flow liners are critical components that increase gas flow efficiency in ductwork. They serve a dual purpose by protecting the expansion joint itself from abrasive media flowing through the system.

Why are Insulation pillows necessary?

Insulation pillows provide thermal protection for the joint. They are essential for maintaining system temperatures while protecting the expansion joint from heat damage.

How do flanges and backing bars improve safety?

Flanges and backing bars are mechanical components that ensure a secure, leak-proof connection to the ductwork. They improve safety and longevity by distributing the load evenly across the connection point.

Building a Resilient System with US Bellows

Pipe stress should not jeopardize your operations. By selecting the right combination of fabric or rubber expansion joints and integrating essential accessories like flow liners, you can build a more resilient ductwork system.

US Bellows engineers resilience into your operations. We provide the precise combination of fabric or rubber expansion joints and essential accessories to absorb stress, eliminate leaks, and ensure your ductwork performs efficiently for years to come.

Stop Unscheduled Downtime

Are you unsure if your current ductwork can handle the stress of thermal expansion or vibration? Book a meeting with a US Bellows engineer to conduct a system assessment and determine the right expansion joint for your piping operation.

The Single Expansion Joint Advantage in Steam Piping

December 9, 2025

US Bellows single expansion joints are engineered for high-cycle steam

In heavy industries, from power generation and chemical processing to refineries, steam is the diligent workhorse. It drives turbines, heats process fluids, and provides motive force. But the very thing that makes steam valuable, its high temperature, is also its greatest challenge to piping integrity. When a steam line heats up from ambient to 1000 °F, effectively becoming superheated steam, the pipe can expand dramatically, creating immense axial forces that threaten to damage anchors, strain pumps, and cause catastrophic failure.

This is where the single expansion joint earns its title as the steam system MVP.

The Problem: Unrestrained Thermal Growth

Steam distribution systems often feature long, straight runs of pipe. The thermal expansion along these lengths is significant and is calculated as pure axial movement: the pipe simply gets longer.

If this movement is not absorbed, it results in:

Massive Anchor Loads: Fixed points must withstand thousands of pounds of compressive force, leading to oversized, expensive support structures.
Equipment Damage: Pumps, valves, and heat exchangers connected to the pipe are subjected to stress, causing premature failure, misalignment, and increased maintenance.
Pipe Buckling: If the line is improperly guided or supported, the immense force can cause the pipe to bend or buckle.

The Solution: The Efficiency of the Single Expansion Joint

The single expansion joint, consisting of one bellows element and end fittings, is the most direct, cost-effective, and efficient component for handling this specific challenge: pure axial movement.

Here’s why single expansion joints are the go-to component for critical high-temperature steam distribution:

Direct Absorption of Axial Movement: They are explicitly designed to compress or extend along the pipe’s centerline, flawlessly absorbing thermal growth without transmitting damaging stresses to connected equipment or supports.
Compact Footprint: Unlike large, bulky pipe loops that require significant space to bend and accommodate movement, single joints fit neatly within the existing pipe run, minimizing structural engineering costs and conserving valuable plant space.
High-Pressure, High-Temperature Capability: Constructed from robust materials such as Inconel-625 or specialized stainless steel alloys, single joints can be engineered to withstand the extreme pressures and superheated temperatures typical of modern steam systems.
Cost-Effectiveness: When the required movement is strictly axial, the single-joint solution is the most economical, requiring less material and a simpler design than universal or pressure-balanced alternatives.

Secure your piping against the forces of thermal expansion, and boost operations with single expansion joints from US Bellows.

US Bellows: Engineered Reliability for High-Cycle Steam

At US Bellows, we provide engineered certainty for your most critical utility systems. We understand that a failure in a refinery’s catalytic cracking steam line or a power plant’s main steam header is not an option.

For your high-temperature, high-pressure steam systems, US Bellows delivers single expansion joints engineered for maximum cycle life, superior materials compatibility (even in corrosive service), and rapid deployment, safeguarding your critical infrastructure against thermal fatigue and minimizing the risk of expensive, unscheduled downtime.

We custom-fabricate every expansion joint with precision bellows technology to match the exact temperature, pressure, and movement requirements of your application and deliver the best performance in the toughest environments.

Don’t Let Thermal Stress Compromise Your Steam System

Whether you’re dealing with live steam, auxiliary steam, or boiler feed lines, securing your piping against the forces of thermal expansion is essential for continuous operation and safety. Rely on the engineered performance of our single expansion joint.

Contact US Bellows today for a consultation on how our single expansion joints can address your high-temperature piping needs.

The Engineer’s Guide to Refractory Selection: A Deep Dive into High-Temperature Expansion Joints

December 3, 2025

Outdoor shot of the back of an engineering manager with a helmet under his arm and a hydrogen power plant in the background.

The success of any high-temperature industrial process, from petrochemical refining to power generation, hinges on the integrity of its refractory lining. However, the aggressive thermal cycles these systems endure can subject the lining and its containment vessels to mechanical stress. This is where the workhorse of high-temperature engineering steps in: the expansion joint.

The Critical Interface: Expansion Joints and Refractory

$Refractory lined expansion joints$ Refractory materials, typically ceramic or concrete, are designed to insulate and protect steel components from extreme heat. Yet, they possess a relatively low tensile strength and are highly susceptible to cracking and spalling when subjected to differential thermal movement.

An expansion joint, integrated into the ductwork or piping system, absorbs the axial, lateral, and angular movement caused by thermal expansion and contraction of the surrounding steel structure. By managing this movement, the expansion joint prevents stresses from being transferred directly into the brittle refractory material, thereby maintaining the system’s structural integrity and keeping the piping’s internal insulation intact.

Key Considerations in Refractory Selection

Choosing the right refractory is only half the battle; ensuring the expansion joint is compatible with the refractory and the operating environment is paramount. Here are the factors an engineer must consider:

Maximum Operating Temperature: This dictates the material for both the refractory and the metallic or fabric expansion joint elements. The insulation thickness will also determine the temperature of the piping and the bellows.
Refractory thickness Trade-off: A thicker refractory lowers piping temperature, allowing the use of cheaper steels such as Carbon steel; however, the piping will be heavier, requiring larger loads and supports. A thinner refractory will yield a higher shell temperature, and the use of stainless steel or alloys for the piping will lower the pipeline’s weight.
Chemical Environment: The presence of corrosive gases (such as SOx or NOx) or particulate matter can lead to premature degradation, requiring specialized alloys or fabric coatings, as well as abrasion-resistant refractories
Thermal Expansion Coefficient: Understanding the difference in expansion rates between the steel duct, the refractory material, and the expansion joint’s liner and bellows is crucial for designing the correct gap and insulation scheme.
Vibration and Fatigue: Systems with high flow rates or cycling operations require bellows designed to withstand the resulting fatigue stress. Vibration may be an issue for refractory, potentially leading to cracking if not accounted for during design.

Protecting the Heat: Integrating Expansion Joints

Mastering Movement: How Expansion Joint Design Preserves Refractory Integrity

The biggest threat to a refractory-lined pipe is the uncontrolled force generated by the thermal expansion of the surrounding steel ductwork. A properly selected and installed expansion joint acts as a pressure-relief valve for mechanical stress, thereby directly extending the service life of the refractory and the piping system.

The Essential Role of Liners and Internal Insulation

The protection of the expansion joint itself is critical. High-temperature metal bellows are often protected internally by a flow liner and refractory insulation.

The flow liner serves a dual purpose: it smooths the flow of media past the bellows, reducing turbulence and vibration-induced fatigue, and it acts as a mechanical barrier to the internal insulation. This internal insulation, often ceramic fiber or a castable refractory material, shields the bellows material from the highest process temperatures. The liner must be designed to allow the bellows to move freely without compromising the insulation’s integrity during the line’s thermal cycling.

This reduction in thermal gradient is critical, as it allows the use of lower-temperature-rated bellows alloys, which are better suited for cyclic operation due to improved cycle life, without the creep phenomenon becoming an issue under constant stress on the bellows. Without this integrated protection, the bellows would be subjected to higher temperatures and operate in the bellows material’s creep range, leading to premature failure.

US Bellows: Your Partner in Customization

At US Bellows, we specialize in custom, refractory-lined, high-temperature expansion joints that are pre-engineered to match the thermal expansion coefficients and chemical composition of your specific refractory system. Our custom solutions minimize stress transfer, virtually eliminate refractory spalling, and drastically reduce the costly downtime associated with high-temperature system failure, providing you with predictable, sustained operational success.

Stop settling for generic solutions that fail under the heat. Contact a US Bellows high-temperature specialist today to design a refractory-matched expansion joint solution that guarantees the maximum service life for your critical assets.

Stop Over-Anchoring: Pressure-Balanced Expansion Joints Slash Installation Costs

November 26, 2025

Pressure Balanced Expansion Joints in Piping Design

The design of a piping system is crucial in industrial settings, where failure can result in damage and downtime. One of the biggest challenges engineers face is managing the immense thrust forces generated by pipeline pressure. These forces can strain anchors, damage equipment, and compromise the entire system. This is where the innovative design of pressure-balanced expansion joints (elbow and in-line) adds value, offering a scalable solution to a complex problem.

What Are Pressure Balanced Expansion Joints?

Pressure-balanced expansion joints are highly engineered components designed to absorb thermal pipe expansion and contraction, as well as lateral movements, while simultaneously neutralizing the pressure thrust force that would otherwise act on surrounding anchors, supports, and equipment.

The Mechanism of Balance

The value lies in their unique internal mechanism. This is accomplished by using a balancing bellows that is exposed to the same pressure as the main, or inline bellows. For in-line pressure-balanced expansion joints, the balancing bellows is specifically designed with an effective area twice that of the inline bellows. For elbow pressure-balanced expansion joints, the effective area remains the same for all bellows.

The core principle is simple but powerful: the pressure acts on both bellows, but the force generated by the balancing bellows acts in the exact opposite direction of the force generated by the inline bellows. Since the entire expansion joint is tied via tie-rods, this creates a state of force equilibrium, effectively containing the thrust from the pressure within the expansion joint.

The thermal movement absorption of the in-line pressure-balanced expansion joints follows that same principle. The inline bellows will compress, while the balancing bellows will actually extend by the same amount as the thermal compression. See our Inline pressure balance EJ below in action:

In-Line Pressure Balanced GIF from US Bellows

This neutralization eliminates the need for large, expensive main anchors, as the only forces the anchors must now contend with are the minor spring forces required to move the bellows themselves. This makes them ideal for systems with limited space, poor structural support, for protecting fragile components, or systems where it’d be impractical or cost-effective to install anchors.

When to Use Pressure Balanced Expansion Joints

These specialized joints are instrumental in situations where the system cannot handle the pressure thrust forces, such as:

Piping connected to sensitive equipment: They protect pumps, turbines, and compressors from axial forces that could cause damage.
Systems with limited structural anchoring: In crowded plants or offshore applications where large anchors are not feasible, these joints offer a compact, effective solution. Also, in situations where the piping is elevated, it would not be cost-effective to install an elevated anchor.
Where Low Loadings Are Needed: In specific applications, especially on large-diameter lines or when connecting to thin-walled equipment, minimizing all loads on the surrounding structure is a primary design driver.

Precision-Engineered Trust: Choose US Bellows

US Bellows is an industry-leading manufacturer of high-quality expansion joints, committed to precision engineering and reliability.

When you specify a US Bellows pressure-balanced expansion joint, you are investing in certainty and safety. Our expansion joints are custom-engineered solutions designed by experts to solve your specific piping challenges. We offer:

Custom Design & Sizing: Every joint is engineered to the precise size, pressure, temperature, and movement requirements of your application, ensuring perfect force neutralization and decades of reliable service.
Unmatched Material Quality: We utilize advanced materials and stringent welding processes, including specialized alloys for high-temperature and corrosive environments, guaranteeing optimal performance and longevity.
Code Compliance & Certification: Our manufacturing adheres to strict industry codes, including ASME Section VIII, Div. 1, and B31.3, ensuring fully certified, safe, and dependable products.
On-site Field Services: We inspect your bellows for loss of pressure, signs of leakage, and observe for specific movement due to pressure.

Stop designing systems around enormous anchors and start protecting your critical equipment with the precision of our solutions at US Bellows.

Ready to reduce pipe stress? Contact US Bellows today to discuss your elbow pressure-balanced expansion joint needs.

Non Metallic Expansion Joints

Product & Application Resources