Dannenbaum LLC logo

Expansion Joints2022-06-14T13:07:39+00:00

Pipe Expansion Joint

Expansion Joints

This article will inform you about expansion joints; there are three main types of expansion joints used on a piping system: metal expansion joints, rubber expansion joints, and fabric expansion joints. They are also known as industrial expansion joints, pipe expansion joints, or flexible joints. A pipe system uses expansion joints for numerous reasons.

First, you can use expansion joints to absorb vibrations and shock. Secondly, you can use expansion joints to relieve anchor stress, reduce noise, and compensate for misalignment.

Furthermore, pipelines can have high temperatures from steam and exhaust gases. Therefore, you can use industrial joints to help prevent any damage to the piping system.

What is an Expansion Joint?

A typical flexible joint has one or more metal bellows (most commonly stainless steel) or materials such as rubber, fabric, or plastic, such as PTFE. While rubber, plastic, and fabric have limitations, metal is the most versatile of all materials.

Metals are suitable for use at high temperatures, as well as, have high strength properties, and are resistant to corrosion. In addition, you can use industrial expansion joints to safely absorb the dimensional changes of steel pipe systems and ducts.

The changes could be heat-induced expansion and contraction, vibrations caused by rotating machinery, pressure deformations, misalignment during installation, or building settlements.

The most important part of the flexible joint is the bellow. We provide bellows with a series of convolutions. The shape of the convolution help withstand the system’s internal pressure but is elastic enough to accept axial, lateral, and angular deflections.

Uses for Pipe Expansion Joints

You can use flexible joints in almost any industry that requires vibration absorption and expansion compensation. You can use these components  for:

  • Energy production
  • Oil refineries and rigs
  • Automotive and engine mechanics
  • Steel and metal processing plants
  • Chemical processors
  • Heating and gas
  • Plumbing

Pipe Expansion Joints Accessories

You can fit flow liners inside the industrial joint to protect the pipe joint from erosion damage. Damage can be due to an abrasive media or vibration from turbulent flow or velocities which exceed:


Industrial expansion joints consist of different components, bellows, liners, cover, end fittings, limit rods, and Tie-down rods. Formerly, people often confuse an expansion joint with a bellow. Moreover, many people think they can use the names interchangeably; this is not true. An expansion joint is a makeup of the components.


Anyhow, a bellow is just one of the components of the joint. The bellow is the body of the pipe expansion joint. Bellows can have convolutions. Also, you can use different materials to make a bellow. Furthermore, the pipe bellow is the flexible unit on the joint.


In addition to the bellows are liners. Liners protect the inside of the piping expansion joint from erosion. A high flow of air, fluids and steam across the inside of the joint can cause damage. Liners can prevent this problem. Liners can reduce turbulence.


Furthermore, an outside cover protects from damage and insulates the pipeline expansion joint. Also, industrial joints can use flanges or butt-weld ends.

Limit Rods

Moreover, you can use limit rods on a flexible joint to limit axial compression or expansion. Further, limit rods allow the piping joints to move over a range. In addition, limit rods can have nut stops. You can use limit rods to prevent the joint’s over-extension while restraining the full pressure thrust of the system.

End Fittings

Industrial joints have end fittings such as flanges or butt-welds. They should match the size and materials of the connecting equipment. Small-diameter flexible joints are available with threaded male ends, butt weld ends, or copper ends. In addition, we can provide threaded flanges.

Tie-down Rods

Anchor rods are also known as tie-down rods. Some tie-down rod features include the following. First, they are a simple structure. Also, they are relatively low-cost. As well, a general configuration can have very low lateral spring stiffness.

Further, high lateral movement in all industries versatility and diffusion of a single or two standard connection structures. Two degrees of movement and three degrees of movement for dual anchor design.

The tie rod contains a structural advantage related to compression force: the instrument compensates for the axial pressure, and only the spring force requires an external anchor. Thus, we can design them to have a meager lateral spring rate.

The tie rod in the expansion joint can continuously limit the total pressure axial force and allow only lateral deflection during regular operation.

The 90-degree composite expansion joint opposite the rotation direction consists of a bellows element connected to the end fitting by a threaded rod or a rod guided by the bellows element. Connect tie rods to the eyelet or ring length limiting ring.

Maintain pressure by tie rods and fasteners. The bound expansion joint has a fixed total length. Use tie rods to help eliminate the axial movement and force at the end of the expansion joint so that they are always parallel. However, this configuration only allows two degrees of freedom transversely on two axes.

Why should I Use a Pipeline Joint?

Pipe expansion joints are critical components of a pipeline used in industries where thermal expansion in pipe systems occurs. Pipe joints also offer the advantage of reducing stresses in pipe systems generated by thermal expansion.

Furthermore, they reduce pipe loads at connections to equipment such as pumps. Engineers and pipe designers often fuse flexible joints in their pipe systems. Pipeline joints add flexibility to the design and reduce costs by eliminating fixed points and guides.

Pipeline joints reduce the overall space requirements for the pipe system. Additionally, pipe expansion joints can be more effective alternatives for pipe bends and pipe loops because of their size. Pipeline joints are economical and great at absorbing more significant movements.

When to use an Expansion Joint

Some designs tell you to use a metal hose or a pipe expansion joint, but sometimes they select the wrong option. A few things let you know if you should use an expansion joint or a hose. These criteria are listed below:

  • Axial Movement
  • Vibration Damping
  • Exotic Material Requirements
  • Space Limitations
  • Size Requirements

Sometimes the solution might not be clear, and instead of deciding between an expansion joint and hose, the best solution could be a mixture of a metal hose with an expansion joint.

Steam Expansion Joints

Steam can cause a temperature rise in a pipe system. Consequently, much movement happens in the pipe. Therefore, you will need an expansion joint for steam. Be sure you pick the correct joint.

What are Piping Expansion Joints?

Piping expansion joints help a piping system, and we can provide them in metal, rubber, and fabric. Moreover, depending on the STAMP (size, temperature, application, media, pressure) will help you determine what expansion joint to use.

How do Industrial Expansion Joints Work?

Industrial expansion joints are also known as pipeline expansion joints that connect items. Also, they safely absorb the high-temperature expansion. You may also use them to offset a pipe or help with movement. Also, you can use them, so a pipeline does not break when a seismic activity or ground movement occurs.

Where are Stainless Steel Expansion Joints in Use?

Steel expansion joints are essential components in many industries and are used extensively in, among others:

  • The energy sector (power plants, nuclear power plants, district heating pipe systems, etc.)
  • Steel plants.
  • Petrochemical industry (oil refineries, pumping stations, oil rigs, etc.)
  • Chemical industries (asphalt manufacturers etc.)
  • Process industry (sugar factories etc.)
  • Exhaust systems and engines
  • Pulp and paper industries.
  • LNG/LPG tankers, carriers, etc.
  • We can install flexible joints near boilers, heat exchangers, pumps, turbines, condensers, engines, and long pipe systems or pipe ducts.

Why Would I Need a Flexible Joint?

  • Thermal expansion of piping.
  • Solve initial piping misalignment and lateral settlement offsets.
  • Pump and equipment vibration.
  • Shock and bending loads.

What are Pipeline Expansion Joints?

Expansion joints are connection points between sections of pipe that move, expand, and contract to compensate for pressure from heat-related variation, vibrations from machinery, and misalignment. Flexible joints are often called compensators, round and rectangular expansion joints, or industrial joints.

People can use them for various applications, including the transfer sections close to boilers, engines, turbines, condensers, pumps, or heat exchangers. In addition, our factory can build flexible expansion joints from various materials depending on the application. You can ask us to help ensure we use the correct pipeline expansion joint.

Industrial Expansion Joints for Pipes

This paragraph will tell you why pipelines use industrial expansion joints. Firstly, misalignment happens in a pipe system. Secondly, thermal expansion occurs in a pipe system. Therefore, it can expand and contract when the pipeline heats and cools.

Pipe bellow joints are also known as compensators for thermal movement. In addition, there are different types of flexible joints for pipes, for example, pipe bellows, pipeline joints, and bellow pump connectors.

How Do Expansion Joints Work?

We provide pipe expansion joints and compensators to hold parts together. Also, they safely absorb high temperature-induced expansion and contraction of building materials. Pipe Joints may also use compensators to make movement safe for the structure, an example, the pipeline movement when seismic activity and ground movement occur.

What are Industrial Expansion Joints Made of?

Pipe expansion joints contain various parts, such as bellows, covers, liners, end fittings, and limit rods. All of these parts make up a quality industrial expansion joint. These components have specific purposes, and they all work together to make the expansion joint function properly.

The makeup of the joint itself may also include a tube, carcass, retaining ring, a mating flange, and a control rod.

Depending on the application, it will determine if a fabric expansion joint, metal bellows, or rubber piping expansion joint is needed and what will work for that specific project.

Expansion joints have a comprehensive range of applications in various industries. They can be engineered to exact specifications and made for easy installation.

Expansion Joint Manufacturers Association, Inc.

EJMA is an organization of established manufacturers of types of metal expansion joints. EJMA was founded in 1955 to establish and maintain quality design and manufacturing standards.

These Standards combine the knowledge and experience of the association’s Technical Committee. They can assist users, designers, and others select and applying joints for safe and reliable piping and vessel installation.

EJMA members are experienced and knowledgeable manufacturers that have demonstrated many years of reliable service to the industry. As a result, EJMA members are the best source for product value, design, and service as reputable manufacturers.

In addition, EJMA conducts extensive technical research and testing on many essential aspects of expansion joint design and manufacturing.

Piping Flexibility

All materials expand and contract with thermal change. In the case of piping systems, this can cause stress on the piping system. Therefore, an expansion joint can be an easy solution.

Pipe Loops

  • Flexible joints design basics -A pipe loop, for example, is looping a pipe for expansion. In addition, this can increase costs and take up room. Increase pipe diameter to compensate for losses due to pressure drop. Therefore, a pipe system can use a pipeline expansion joint.
  • Pipe for expansion design basics – The most efficient piping system is the shortest and most directly routed pipe system. Therefore, flexible joints make this possible.
  • Pipework Expansion joints provide an excellent solution for isolation, seismic deflection, mechanical vibration, and sound reduction.

Pipe Expansion Joint Design Basics

Expansion joints consist of flexible bellows, appropriate end fittings such as flanges or butt-weld end to allow connection to the adjacent piping or equipment and other required accessory items that may apply for a particular service application.

Movement Capabilities For Industrial Joints

  • Axial Compression: Reduction of the piping expansion joint length due to piping expansion.
  • Axial Extension: Increase the pipeline expansion joint length due to pipe contraction.
  • Angular Rotation: Bending about the longitudinal centerline of the joint.
  • Lateral Offset: Transverse motion is perpendicular to the pipe plane, with the joint ends remaining parallel.
  • Torsion: Twisting about the longitudinal axis of the joint can reduce pipeline joint life or cause common failure and should be avoided.
  • Do not locate Industrial joints at any point in a piping system that would impose torque on the joint due to thermal change or settlement.

Cycle Life

Cycle life is how long the joint will last. For example, think of a rubber band. How often can you extend a rubber band until it doesn’t return to its original size or until it breaks? Likewise, pipeline joints need to last for a while.

Therefore, cycle life of one or two thousand cycles is usually the best. However, high cycle life designs may be desirable for service applications that include frequent start-up/shut-down processes.

The piping designer considers such design variables as material type, wall thickness, the number of convolutions, and geometry to produce a reliable design for the intended service with a suitable cycle life expectancy.


An internally pressurized pipeline expansion joint behaves like a slender column under compressive load. At some critical end load, the column will buckle, and similarly, at sufficient pressure, internally pressurized flexible joints installed between fixed points will also buckle or squirm.

Recognize load piping joint squirm by a gross lateral shift of the convolutions of the longitudinal centerline. Expansion joint squirm can reduce cycle life or produce a catastrophic failure in extreme cases. To avoid squirming, the joint designer must limit movement capacity and flexibility. For example, you can use control rods.

For air, steam, and other gases.

Up to 6” dia.- 4 ft./sec./inch of diameter. Above 6” dia. -25 ft/sec.

For water and other liquid

Up to 6” dia. – 2 ft./sec./inch of diameter. Above 6” dia. -10 ft./sec.

Expansion Joint Covers

Covers are mounted at one end of the flexible joint, providing a protective shield that spans the length of the piping expansion joint.

Covers prevent direct contact with the industrial expansion joint, offer personnel protection, and protect the pipe expansion joint from physical damage such as falling objects, weld splatter, or arc strikes.

Covers also provide a suitable base for external insulation over a joint. However, some insulating materials, if wet, can leach chlorides or other substances that could damage a pipeline expansion joint.

Tie rods eliminate pressure thrust and main anchors required in an unrestrained piping system. Prevent axial movement with the use of tie rods.

Designs that have only two tie rods have the additional ability to accommodate angular rotation. Limit rods are similar. However, they accommodate a specified axial capability.

Pipework Expansion Joints

You must install all pipes at room temperature. Pipes that hot transport liquids (such as water or steam) work at higher temperatures. Therefore their length will expand significantly when the ambient temperature rises to the operating temperature.

Create tension in certain areas within the distribution system (such as pipe connections), which may break extreme cases. Then, as the system heats up, they move to each other.

Pipework Flexibility

The piping system must be flexible enough to support the movement of components during expansion. The piping system is flexible due to the length of the pipe and the number of bends and supports. Therefore, in many cases, it does not generate excessive stress.

Other settings should include methods to achieve this required flexibility. A typical steam system is the condensate discharge pipe from the condensate return line to the condensate return line extending along the steam line. The pipe system should consider a two-pipe system here.

The temperature of the fresh steam pipe is higher than that of the main condenser pipe, and the two connection points move relative to each other during the warm-up system period. “Cold pressing” can reduce the number of movements the pipeline and its built-in equipment must perform. But first, calculate each part’s total elongation between the fixed connection points.

The system is loaded in one direction at room temperature and coldly pulled. When expanding, use the tube in the opposite direction. The effect is that instead of pulling the pipe from 0F to +1F force units, it stretches from –½ F to +½ F force units.

In practice, the pipeline is cold-installed, with half the extension length between the two flanges in the middle. When the pipe is fully assembled and fixed at both ends, remove the gasket and pull out the connection.

What Are They Used For?

Pipework joints have unique and essential functions. They reduce vibration and shock on systems, minimize noise, relieve pipe stress, and sometimes compensate for thermal expansion. Other uses for flexible joints may be anti-vibration, earthquake movement, and building settlement.

Thermal Expansion Stress

Thermal Expansion Goal At the end of this section, you should solve problems related to infinite thermal expansion.

Some materials expand or contract more than others; the qualitative characteristic of how much they grow is called the coefficient of linear thermal expansion (α) in units of m/(m ºC) or (in/in ºC). Units such as 1ºC or 1ºF can also be the same.

Calculate the length change caused by thermal expansion as follows: Where δ is the change in length, L is the original length (ensure their units are the same), and ΔT is the temperature difference.

For example, if the thermal expansion coefficient of steel is 11.7 × 10 6 1 / ºC, if the temperature rises by one °C, a 1 m long rod will expand by 11.7 × 10 6 m, or 0.0117 mm.

It may seem like a small number, but if you look at a 50 m steam pipe installed at 12°C and operating at 212°C (saturation pressure 2000 kPa), the thermal expansion is equal to 11.7 cm or equivalent. 0.002 is essential for pipeline designers need to consider this expansion or calculated stress. (Isotropic material) Using (3 × α) as the expansion coefficient, you can compute similarly.

When calculating the volume expansion of the liquid, the volume expansion coefficient is β, the typical value listed in the engineering toolbox.

The expansion pipeline is usually relatively long, and the installation and working temperatures may increase significantly. Therefore, I designed the bracket correctly to prevent high thermal expansion stress.

Cold Extraction

In addition, the expansion of the pipeline increases the load on the nozzle and equipment container. There are many articles and discussions on this topic in the design of cold spring pipes. A cold spring tube is defined as deliberate deformation during assembly (usually by cutting a short or long tube between two anchors) to obtain the required initial displacement and tension.

It is also defined as the piping system’s deliberate stress and elastic deformation during the assembly cycle to allow the system to achieve a more favorable response and stress under operating conditions. You should be familiar with this procedure when using steam lines.

The contractor hired to remove the steam pipe may complain about the improper installation of the line; after unscrewing, the pipe comes out again. By familiarizing yourself with this procedure and understanding your factory, avoid costly repairs and unnecessary modifications.

Compared with normal operating conditions, as the temperature drops, most steel becomes more brittle for low-temperature pipeline supports, so it is necessary to understand the temperature distribution under low-temperature conditions.


Please provide STAMP (size, temperature, application, movement, pressure).