There are three main types of expansion joints used on a piping system: metal expansion joints, rubber expansion joints, and fabric expansion joints. They’re all types of industrial expansion joints.
Pipe expansion joints are also known as flexible joints. A pipe system uses pipework expansion joints for numerous reasons.
First, pipework expansion joints can absorb vibrations and shock. Secondly, you should use pipeline expansion joints to relieve anchor stress, reduce noise, and compensate for misalignment.
Additionally, some pipelines have high temperatures from steam and exhaust gases. Therefore, industrial expansion joints must operate properly and help prevent any damage or piping system.
What Are They Used For?
Pipework joints have unique and essential functions. They are used to reduce vibration and shock on systems, minimize noise, relieve pipe stress, and in some cases, compensate for thermal expansion. Other uses for flexible joints may be anti-vibration, earthquake movement, and building settlement.
Industrial expansion joints consist of different components, bellows, liners, cover, end fittings, and limit 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. However, a pipeline expansion joint consists of all the components.
Anyhow, a bellow is just one of the components of the joint. For example, the bellow is the body of the pipe expansion joint. Bellows can have convolutions. Also, we can use different materials to make a bellow. For example, the pipe bellow is the flexible unit on the joint.
In addition to bellows are liners. Liners protect the inside of the piping expansion joint from erosion. When a high flow of air, fluids, steam flows across the inside of the joint, it 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.
Moreover, we can limit rods on a joint expansion design 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. So Furthermore, limit rods are used to prevent the joint’s over-extension while restraining the full pressure thrust of the system.
Why should I Use a Pipeline Joint?
Pipeline 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 fixpoints 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:
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 Joint
Steam can cause temperature rise on a pipe system. Therefore, much movement happens in the pipe. Consequently, you will need an expansion joint for steam. Be sure you pick the correct joint. Moreover, when asking for an RFQ, it helps to have the following information.
Firstly you need size. Secondly, you need temperature. Next, you will need the application. Then you need to know the material. Lastly, you’ll need to see the pressure.
What are Piping Expansion Joints?
Pipeline expansion joints are used in a piping system and are made of three materials—metal, rubber, and fabric. Moreover, depending on the STAMP (size, temperature, application, media, pressure) will help you determine what Industrial expansion joint to use.
How do Industrial Expansion Joints Work?
Industrial expansion joints are 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. For example, a pipeline does not break when a seismic activity or ground movement occurs.
What is an Expansion Joint?
A typical flexible joint comprises one or more metal bellows (most commonly stainless steel) or from materials such as rubber, fabric, or plastic such as PTFE. While materials such as rubber, plastic, and fabric have their 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, we offer 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.
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.)
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 expansion 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.
Having a reliable piping system is needed in piping.
What are Pipeline Expansion Joints?
Pipeline 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 flexible 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. Ask an experienced engineer to help make sure the correct type of pipeline expansion joint is utilized.
Uses for Pipe Expansion Joints
You can use flexible joints in almost any industry that requires vibration absorption and expansion compensation. Some of the sectors that these components are commonly used for include:
Oil refineries and rigs
Automotive and engine mechanics
Steel and metal processing plants
Heating and gas
Industrial Expansion Joints for Pipes
In this paragraph, I will discuss why pipes use Industrial expansion joints. Firstly, misalignment happens in a pipe system. Secondly, thermal expansion occurs in a pipe system. Therefore, when the pipeline heats and cools, it can expand and contract.
Pipe bellow joints are also known as compensators because they compensate for the thermal movement. In addition, there are different types of names for flexible joints for pipe, 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, cover, 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 industrial 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.
Industrial expansion joints have a comprehensive range of applications in various industries. They can be engineered to exact specifications and made for easy installation.
The 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 carries out extensive technical research and testing on many essential aspects of expansion joint design and manufacturing.
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.
Flexible Joints design basics -Pipe loop, for example, is looping a pipe for expansion. In addition, this can increase cost and take up room. In some cases, pipe diameter must be increased 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
Pipework for expansion joints consists 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 Expansion 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. Joints should not be located at any point in a piping system that would impose torque to the joint due to thermal change or settlement.
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 the 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 way. 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.
Load piping joint squirm is recognized by a gross lateral shift of the convolutions off 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. This is done with control rods.
Expansion 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. We also supply threaded flanges.
Pipe Expansion Joints Accessories
Flow liners are fitted inside the industrial expansion 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:
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. In addition, axial movement is prevented 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.
This creates 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.
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 that the pipeline and its built-in equipment must perform. First, calculate the total elongation between the fixed connection points for each part.
By pulling the screws on the flange connection, the system is loaded in one direction at room temperature and coldly pulled. When expanding, the tube is drawn 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.
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.
The length change caused by thermal expansion is calculated as follows: Where δ is the change in length, L is the original length (make sure 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.
This 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 very important for pipeline designers because they need to consider this expansion or calculated stress. (Isotropic material) It is computed similarly using (3 × α) as the expansion coefficient.
When calculating the volume expansion of the liquid, the volume expansion coefficient is β, and the typical value is listed in the engineering toolbox.
The expansion pipeline is usually relatively long, and the installation temperature and the working temperature may increase significantly. If the bracket is not designed correctly, this can cause high thermal expansion stress.
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. Use the keywords “Cold Spring Tubing” or “Cold Spring Tubing” to quickly access groups via an internet search.
This is also included in ASME B31.” 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 in the process.
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. Maintenance technicians familiar with this procedure are recommended to use 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.
For low-temperature pipeline supports, compared with normal operating conditions, as the temperature drops, most steel becomes more brittle, so it is necessary to understand the temperature distribution under low-temperature conditions.
In addition, steel structures have high-stress areas, which may be caused by sharp corners in the system or inclusions in the material.
Anchor rods are also known as tie-down rods. Some tie-down rods 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 structure. 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 (EJ) 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. The tie rods are connected to the eyelet or ring length limiting ring.
Pressure is maintained by tie rods and fasteners. The bound expansion joint has a fixed total length. The way the tie rods are placed can eliminate the axial movement and force at the end of the EJ so that they are always parallel. However, this configuration only allows two degrees of freedom, transversely on two axes.