FAQs

WHAT ARE BELLOWS AND EXPANSION JOINTS? Bellows and expansion joints are flexible components used in piping systems to absorb movement, vibration and thermal expansion. Bellows are typically made of metal and consist of a series of convolutions that allow for flexibility. Expansion joints, which include bellows as a key component, can be metallic, rubber or fabric and are designed to accommodate various types of movement, including axial, lateral and angular displacement, ensuring the integrity and longevity of piping systems.

HOW DO EXPANSION JOINTS WORK? Expansion joints work by allowing controlled movement within a piping system and potentially restricting or limiting other types of movement. They absorb thermal expansion and contraction, reduce vibration and compensate for misalignment. The flexible element, often a metal bellows or rubber/fabric section, expands and contracts as needed, either axially, laterally, angularly or a combination of these, thus protecting the system from stress and potential damage. By accommodating these movements, expansion joints help maintain system integrity and prevent leaks or failures.

WHAT IS THE DIFFERENCE BETWEEN BELLOWS AND EXPANSION JOINTS? Bellows are the flexible, corrugated parts of an expansion joint that allow for movement and flexibility. Expansion joints, on the other hand, are complete assemblies that include bellows and additional components like tie bars, limiting rods and restraints, hinges and gimbal arrangements. While bellows provide the flexibility, expansion joints provide a comprehensive solution to manage movement, pressure and thermal changes within piping systems.

WHAT MATERIALS ARE BELLOWS AND EXPANSION JOINTS MADE FROM? Bellows and expansion joints are made from various materials depending on the application. Metallic bellows are typically made from stainless steel or other high-strength alloys for their durability and resistance to high temperatures and pressures. Rubber expansion joints are made from elastomers like EPDM, neoprene or nitrile, which offer good flexibility and chemical resistance. Fabric expansion joints use various materials including fiberglass and silicone-coated fabrics to handle a wide range of temperatures and corrosive environments.

WHERE ARE EXPANSION JOINTS TYPICALLY USED OR REQUIRED? Expansion joints are used in a variety of industries, including power generation, petrochemical, HVAC, water treatment and industrial processing. They are commonly found in piping systems, ductwork and equipment that experience thermal expansion, vibration or misalignment. Specific applications include steam lines, exhaust systems and pump connections, where they help to manage thermal growth, reduce noise and vibration, and protect the integrity of the system.

WHAT ARE THE TYPES OF BELLOWS USED IN INDUSTRIAL APPLICATIONS? There are several types of bellows used in industrial applications, including single-ply and multi-ply bellows, formed and welded bellows, and convoluted and non-convoluted bellows. Single-ply bellows are made from a single layer of material, while multi-ply bellows have multiple layers for added strength. Formed bellows are made by shaping metal sheets and welded bellows are made by welding individual rings or tubes. Convoluted bellows have ridges for flexibility and non-convoluted bellows are smooth for specific applications.

HOW DO I CHOOSE THE RIGHT EXPANSION JOINTS FOR MY APPLICATIONS? Choosing the right expansion joint involves considering several factors, including the type of movement (axial, lateral, angular), pressure and temperature conditions, the material compatibility with the media being transported, and the physical space available for installation. It is essential to consult with manufacturers or experts to ensure the expansion joint meets the specific requirements of the application, such as accommodating thermal expansion, reducing vibration and handling the required pressure and temperature ranges. Teddington is a leading specialist in bellows expansion joints and we will always provide assistance in correct selection.

WHAT IS THE LIFESPAN OR LIFECYCLE OF AN EXPANSION JOINT OR HOW LONG DO EXPANSION JOINTS LAST? The lifespan of an expansion joint depends on several factors, including the material, operating conditions and maintenance practices. Metallic expansion joints can last for many years, depending on the environment and usage, while rubber and fabric expansion joints generally have shorter lifespans, due to the natural degrading of the material. Regular inspections and maintenance can extend the lifespan by identifying and addressing issues before they lead to failure. As a leading member and contributor to the EJMA Standards, Teddington specialises in optimising the lifetime of bellows expansion joints.

HOW DO I INSTALL EXPANSION JOINTS? Proper installation of expansion joints involves several steps. First, ensure the expansion joint is the correct size and type for the application. Align the piping system correctly to avoid misalignment stresses. Install the joint with the specified anchors and guides, ensuring it is not subjected to torsion or excessive displacement during installation. Follow the manufacturer's installation guidelines, including tightening bolts to the recommended torque and checking for leaks after installation. Proper installation ensures optimal performance and longevity of the expansion joint. Teddington will always provide guidance and can even provide in-person assistance in the correct installation and maintenance of bellows expansion joints and associated pipework.

WHAT ARE THE COMMON FAILURE MODES OF BELLOWS? Common failure modes of bellows include fatigue cracking, corrosion, erosion and mechanical damage. Fatigue cracking occurs due to repeated flexing and stress cycles, leading to material failure. Corrosion can result from exposure to aggressive chemicals or environments, weakening the material. Erosion occurs when abrasive particles in the media wear away the bellows surface. Mechanical damage can occur during installation or operation, such as dents, tears or punctures, compromising the bellows' integrity and performance.