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 alignment imperfections. Expansion joints are also often called compensators, expansion bellows, or flexible joints, and they can be used for a variety of applications, including the transfer sections close to boilers, engines, turbines, condensers, pumps, or heat exchangers.
Benefits of Pipe Expansion Joints
Pipe expansion joints protect against thermal expansion
An pipe expansion joints primary purpose is to prevent a system failure, a resultant stoppage, and the expensive repairs to restore everything back to working order. They accomplish this through several mechanisms. First, expansion joints anticipate thermal expansion, which occurs as temperatures rise inside the system. Rising temperatures in general induce expansion, and this causes otherwise regular, straight piping to bend and distort or even crack. Expansion joints limit this by moving with pipes’ expansion and accommodating axial, down-the-line forces. Basically, these joints give the system some flexibility that responds to changes in pipe size.
They protect against vibrational resonances
Another mechanism through which an pipe expansion joints saves a pipe system is vibrational resonance mitigation. Fluids passing through pipes apply force to the pipes that, when built up over time, resonate dangerously along the length of the pipe. The longer the pipe, the more likely these forces can resonate strongly and induce cracking. Expansion joints are important tools for stopping this resonance because they break up pipe systems into smaller segments and also can move with certain built-up forces in several directions.
Advantages over a pipe loop
Pipe expansion joints marked advantages relative to pipe loops are another benefit to using pipe expansion joints. While each are effective implements when accounting for thermal expansion, expansion joints are decidedly more space efficient. The defining feature of a pipe loop is its U-shape, and this requires ample space within a facility to create. On the other hand, expansion joints are practically flush with the rest of the pipe system and don’t take up extra space. This means they are more practical for facilities that are short on space. Also, pipe loops are not realistic inclusions in low-pressure systems, making expansion joints—which preserve a system’s pressure more consistently—the better option.
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Pipe Expansion Joint Structure
Tube
A protective, leak proof lining made of synthetic or natural rubber. The tubes primary function is to eliminate the possibility of materials being handled penetrating the carcass.
Retaining ring
Used to compress the expansion joint flange to the mating flange to create a seal. Also called clamp bars or backing bars. Applies to most all expansion joints.
Carcass
The carcass or body of the pipe expansion joints consists of fabric, and when necessary metal.
Cover
The exterior surface of the joint.
Fabric reinforcement
The carcass fabric reinforcement is the flexibility and supporting member between the tube and cover.
Metal reinforcement
Wire or solid steel rings imbedded in the carcass, often used for strengthening.
Mating flange
Used to connect the pipe joint to the pipe in which it is being installed.
Control rod
Used to limit the axial movements during operation, and prevent the joint from exceeding its movement capabilities. The rods attach the mating flange and expansion joint. Typically used on piping joints, but can be installed on most any joint when required.
The 5 Most Common Types of Pipe Expansion Joints
Meanwhile, universal expansion joints handle lateral forces and angular rotation in addition to axial forces. Lateral forces act in a perpendicular direction to a plane. So in this case, this would involve holding the soda can as if you were going to drink and pressing the side of it with one hand. Angular forces twist, as if you used your hands to turn against one another and compress the soda can. This is possible because universal joints consist of two bellows and a section of pipe. When axial, lateral, and angular forces are strong, universal joints are a good option.
Gimbal
Comparable to a hinged joint, a gimbal joint has hinges that allow free movement in any direction. This enables a high degree of pipe movement because it moves with every direction of lateral force. Gimbal joints are good tools for eliminating as much pressure thrust as possible.
Simple
Simple pipe expansion joints specifically withstand axial forces. Axial forces act upon the pipe’s axis. It is like the force used to crush a can of soda by placing your hands on the top and bottom of the can and pushing one hand to meet the other. Mitigating these crushing forces makes simple expansion joints effective at protecting your pipes.
Pressure balanced
One specialized type of pipe expansion joint is the pressure balanced expansion joint. These can be either the elbow or in-line variety and are usable when it’s not feasible to anchor a joint to limit axial motion. To ensure the axial forces don’t overwhelm the system, pressure balanced joints employ bellows that oppose one another to cancel some force. Also, the joint contains axial forces because there is a cross-sectional element that stabilizes the joint.
Hinged
Hinged expansion joints, similar to universal joints, address lateral forces primarily. Fitting its name, it’s set apart by the hinge placed near a bellow to bear lateral forces in one orientation. You can also restrict one direction of the hinge by welding and supporting one side and not the other.
Pipe Expansion Joint Materials
Metal
Pipe expansion joint structure are mostly used in applications where thermal expansion is an issue. When the temperature of the pipe increases, the metal expansion joint compresses to compensate for the movement, taking stress off the anchors and the pipe. A metal expansion joint is a prime example of how to handle expanding hot pipes.
Rubber
Rubber can be used for thermal expansion, and it also absorbs vibration and shock waves extremely well. That’s why this type of Pipe expansion joint structure is great for minimizing the transmission of noise, vibration from other equipment to protect equipment like pumps. They also work as shock absorbers to minimize trauma caused by water hammer, pressure surges, and seismic events (not that we get a lot of earthquakes in Wisconsin…).
Braided
Braided stainless hoses with flexible or metal liners aren't technically an expansion joint, more of a flexible connector. They work well in high pressure and temperature applications requiring vibration dampening or pipe misalignments.These are often used on pumps and other equipment to help eliminate thrust load on the equipment nozzles due to thermal expansion. Eliminating that load is critical to pump performance.
The Dos and Don'ts of Storing Your Metal Pipe Expansion Joints
It's best to always store metal pipe expansion joints in a clean indoor area away from direct sunlight, preferably on chocks. However, if you keep them on the floor, the surface should be even, solid, and dry to avoid watermarks and rust on steel.Expansion joints should lay flat to prevent damage and deformation, and they should be away from sharp objects. It's also best to keep expansion components away from oil, grease, and chemicals, preferably in separate rooms.
Storing expansion parts in their original packaging until installation preserves component integrity. The packaging also protects parts from foreign debris entering and lodging in internal flow sleeves and convolutions.
Many cleaning solutions and soaps contain harsh chemicals responsible for stress corrosion. When cleaning stored metal pipe expansion joints, you should use only isopropyl alcohol and a soft cloth to wipe surfaces gently.Avoid using abrasive cleaning tools like brushes and steel scrubbers when cleaning metal expansion components.
It's best to store metal expansion parts next to one another. However, there are extreme cases where you have limited space and no alternative. If you find yourself in such a situation, you can stack bellows on top of one another in a manner that preserves components and mitigates the risk of stacks falling over.These are the dos and don'ts of storing your metal expansion joints. Remember to place them in a clean, dry area free of heavy traffic or damaging factors. Inspect parts for damage such as dents, broken components, and watermarks on storage cartons. When stored properly, expansion joints can last longer.
How to Choose Pipe Expansion Joints
Piping plan
Before addressing the pipe expansion joints itself, ensure that adjacent piping and equipment conforms to Good, solid piping engineering practices. Basically, this means the proper placement and design of the anchors, guides and supports are important for the expansion joint to function properly.
Joint movement
Since pipe expansion joints and pump flexible connectors are employed to absorb axial, lateral and angular pipe movement, as well as vibration, careful consideration should be made to correctly calculate those movements. It is important that the correct coefficient of thermal expansion (CTE) is used. The specific pipe material must be known since the CTE differs greatly between pipe materials. These differences can affect calculated movement to a point that the pipe movement may greatly exceed the expansion joint’s capability when initial calculations show that they are within its limits.
Pumped media
Determining the process media is also important since new chemicals are processed every year. The media is one of the most important determining factors for compatible elastomer selection. Material selection must not be compromised during the specifying process. Choosing a marginal tube material is risky and invites high replacement costs and/or downtime. Any abrasive material in the media should also be investigated since even minute amounts of abrasive material at high velocity can wear out a tube prematurely. A protective liner or filled arch design should be investigated. Conservatism is the best policy since a compromised product can lead to rapid deterioration and failure. It is recommended that severe service joints carry material certification requirements and that material properties are checked to confirm that the material certification matched the pumped fluid.
Pressure and temperature
Accurate temperature and pressure data is important and should be included in the analysis of the application’s requirements. When temperatures exceed 200 degrees Fahrenheit (93 degrees Celsius), proper pressure de-rating should be made to ensure that the expansion joint or flexible connector can handle the system working pressure at the maximum elevated temperature. Pressure de-rating is required to prevent potential deterioration of the reinforcing fabric.When connectors are used at discharge, pulsating or shock pressure should be investigated. A general rule is that the pipe expansion joints or flexible connector should be rated to withstand four times the system working to compensate for shock pressure.
Anchors
High quality, reliable anchors should be employed that will withstand the joint pressure thrust and force resulting from the pipe motion. The use of control rods or limit bolts is also recommended as a backup for the possibility of anchor failure. These rods prevent the joint from extending or pulling apart if a restraint anchor were to fail or blow out. The use of control rods is an inexpensive insurance policy. Non-metallic pipe expansion joints systems, when designed properly and applied correctly, can last 30 years or more. One example is an application in which high pressure cooling water was passing through an ethylene propylene diene monomer (EPDM)expansion joint with a 132-inch internal diameter at more than 200 degrees F (93 degrees C) in a nuclear power facility. When removed, the expansion joint showed little wear and increased durometer hardness after more than 25 years of service.
Application of Pipe Expansion Joints
HVAC systems
Pipe expansion joints are used in heating, ventilation, and air conditioning (HVAC) systems to absorb the movement of pipes caused by temperature changes. This can include ductwork, piping, and even the equipment itself.
Power plants and industrial applications
Pipe expansion joints are commonly used in power plants and other industrial applications where high temperatures and pressures are present. They are used in steam pipes, exhaust systems, and other areas where thermal expansion and contraction are significant factors.
Chemical processing
The chemical processing industry also relies on pipe expansion joints to accommodate thermal movement. These joints are typically used in high-temperature piping systems that carry acids, chemicals, and other hazardous materials.
Marine and offshore applications
Pipe expansion joints are also used in marine and offshore applications to accommodate the movement of pipes due to the movement of a ship or oil rig. They are critical for maintaining the structural integrity of the system and preventing damage from the movement of pipes.
Food and beverage industries
Expansion joints are used in food and beverage processing plants to accommodate thermal changes in piping systems and isolate vibration from equipment, such as pumps and compressors.
Pharmaceutical industries
Pipe expansion joints are used in pharmaceutical manufacturing processes to minimize contamination risks from system vibration and pulsation, and also to accommodate thermal expansion.
Company Profile
Chengde Rui Mai Trading Co., Ltd. is a professional and competitive supplier of pipes, valves and fittings in China. It is more than 10 years’ experience of helping foreign customers to develop the high quality and suitable valves, strainers, electric actuator and pipe fittings.
Since 2010, we have been successful cooperation with some European companies and Southeast Asian companies for OEM production of wafer butterfly valves and resilient gate valves in China. The fittings with “EH” brand owned by us are so popular in the foreign countries, such as Malaysia, Thailand, Vietnam, Egypt and Russia.
We can offer kinds of selection of the competitive industrial valves, strainers and pipe fittings. We can supervise the quality of the products in each order in the factory as part of your quality control department in China. We also can make investment to develop your special valves or fittings that are popular in local market.
Contact Rui Mai company today and discover the many ways we can help you and your organization with your high-quality valves, fittings, strainers and electric actuators. We believe we are the right one for you.
Asked Questions
Q: What is the rule of thumb for pipe expansion?
Q: Why do expansion joints fail?
Q: How do I choose an expansion joint?
Q: How important is expansion joints?
Q: What is the 1500 rule in piping?
Q: What is expansion joints in plumbing code?
Q: How far apart should expansion joints be?
Q: Is it normal for expansion joints to crack?
Q: What would happen if there were no expansion joints?
Q: How often do you need to replace expansion joints?
Q: What is the rule for 2 pipe size?
Q: Where are expansion joints necessary?
Q: What is the rule for expansion joints in PVC?
Q: What is the difference between a flex joint and an expansion joint?
Q: What is the most common joint problem?
Q: What information do engineers consider when using expansion joints?
Q: What are the three types of expansion joints?
Q: How deep do you cut expansion joints?
Q: How do you seal cracks in expansion joints?
We're professional pipe expansion joints suppliers in China, specialized in providing high quality products and service. We warmly welcome you to buy customized pipe expansion joints at low price from our factory. For more cheap products, contact us now.
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