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Expansion Joints Keep your Production Moving

Expansion Joints Keep your Production Moving

Piping systems are the life blood of many heavy industrial markets. Any time air, gases, or liquids need to be moved, there is a heavy investment in the piping systems to get them from place to place.
Even in a food processing plant there is a need for specially heated piping systems to move corn syrup from its storage container to the processing area.
If you are trying to make a 2000 LB. batch of chocolate syrup and the pipe isn’t heated properly, then the corn syrup is not going to move in the pipes, and it may take 8 hours to start flowing.
Now, if you have hot and cold material handling lines in your plant, then you have expansion joints. You know your business, and you know that in order to be profitable, your system must run at maximum efficiency.
Metal expansion joints allow for both movement and containment in your plant so that stresses don’t built up and cause a problem at the wrong time. And even if you specifically set aside time for maintenance, problems seem to gravitate more toward the critical moments when you don’t need them.
Metal expansion joints allow for the flow of fluids or gases in your system under all the specified conditions they are designed for. Note I said “designed for.”
They won’t hold up to stress that is beyond rated capacity. Knowing the conditions and allowing for unforeseen conditions is the trick to a reliable system that will serve you consistently.
You can imagine that problems of a joint failure in a submarine, for example. Your situation may not be that “Mission Critical,” but hot oil spraying on the plant assembly area is no picnic either. It happens. I won’t go into the most efficient methods of cleaning up hot oil. That’s another story.
Metal expansion joints may experience one or a combination of lateral, axial, angular, or twisting movements. Your specs should take all these motions into account. Often an exterior restraining system will keep the joint itself from being over-stressed to the point of separating.
Every joint has its limits. There are engineering solutions for a number of inherent weaknesses in an expansion joint system. If a bellows is needed in a high pressure situation, an exterior chamber can be added to equalize the pressure both inside and out so that the weakness of the bellows structure is less of an issue.
In order to limit total movement, tie rods can form a limiting cage that keeps and expansion joint from going too far. Or a hinge can be added to one side of a joint which limits the motion to a very predictable plane of action that is easier to design for.
Rather than accommodate all motions at once, multiple expansion joints can be used in series either to add flexibility or to increase the total amount of motion tolerated. Sometime internal sleeves serve to protect the joint from materials that might interfere with its smooth operation.

Heat And Pressure? Metal Expansion Joints Are The Answer – Flex Your Joints Or Pay The Piper

Heat And Pressure? Metal Expansion Joints Are The Answer – Flex Your Joints Or Pay The Piper

Piping; lots of piping, maybe miles of it. Look at the schematic. Straight lines; bends; right angles; every twist and turn requires expansion joints. It makes the Los Angeles freeway system looks like child’s play. Whether the piping is one inch diameter, or 200; whether the system operates at full vacuum, or 2000 psig, at full capacity, there is considerable pressure. Depending on the medium, the system may have to accommodate 4000 degree heat or -325 degree cold. Pressure and temperature cause expansion and contraction. The result is stress on the system and the system engineer. The mission? Control the flow and keep the operation running at optimal capacity and efficiency.

The answer? High quality Metal Bellows Expansion Joints. Expansion joints allow movement of a medium through a piping system while containing the medium, and controlling system pressure. Thermal growth or diminution, equipment movement, vibration or pressure anomalies can cause movement in a piping system. Metal Expansion Joints are an excellent, and often essential, solution, to piping system movement.

The expansion joints may experience one or a combination of axial, (straight line); angular, (longitudinal rotation); lateral, (shear); or torsional, (twisting), movement. Insertion of these metal expansion joints into the system, of course, requires end connections. End connections may require flanges, or specialized flanges, including “slip-on, “angle,” or perhaps “Vanstone” modified flanged ends with the flexibility of resolving bolt-hole misalignment. Weld end connections can also be used to mate metal bellows expansion joints to any pipe or duct in a system. A variety of unrestrained and restrained metal bellows expansion joints are available to increase system integrity.

Unrestrained metal expansion joint assemblies include: – Single Joint Assemblies, the simplest type, consisting of a single metal bellows welded to either a flange or pipe end. – Universal Expansion Joint Assemblies allow more flexibility with regard to axial, lateral and angular movement, by connecting two bellows with flange or pipe ends with a center spool piece. – Externally Pressurized Expansion Joints allow line pressure to act externally on the bellows component through inclusion of a pressure chamber. This configuration provides more convolutions to be used to control significant axial movements, and negates concerns of bellows instability. Standing media concerns are allayed by the benefit of self-draining convolutions. Proper installation requires appropriate anchors and guides.

With respect to restrained Metal Expansion Joint Assemblies, four clear choices emerge: – Tied Single Bellows Assemblies combine the Single Bellows Assembly with tie rods, thereby increasing piping system design flexibility. Main anchors are unnecessary as the system thrust pressure is carried by tie rods attached to the flange or pipe with lugs. – Tied Universal Assemblies, similar in manufacture to Universal Assemblies, limit lateral offset and angular movement by utilizing tie rods to absorb pressure thrust. – Use of Hinged Bellows Assemblies limits angular movement to one plane. The configuration of two or three Hinged Bellows Assemblies is typically employed in high pressure piping situations to handle large amounts of expansion. – Finally, Gimbal Bellows Assemblies are engineered to allow angular movement in all planes, while absorbing pressure thrust and torsional movement. Gimbal Assemblies, when paired, or used in conjunction with a Single Hinged unit, are particularly suited to maximize absorption in multi-planer piping systems.

Complimenting and enhancing the various Metal Bellows Expansion Joint assemblies are numerous options and accessories. Ties rods, referred to above, typically devised as rods or bars, attach to an expansion joint assembly for the purpose of mitigating both the inevitable pressure loads, as well as ancillary forces such as dead weight. Limit rods are a “fail-safe” methodology designed to address the situation of occasional anchor overload or system malfunction which, otherwise, could cause metal bellows joint expansion beyond design parameters. Limit Rods are a precautionary measure that does not come into play under normal operating conditions. Liners are internal sleeves which are used to protect the internal surface of the metal bellows from media which may compromise its integrity. In high temperature media conditions, such as oil industry applications, Purge Connections are used in tandem with Liners to keep the bellows within acceptable tolerances. Covers, otherwise known as “shrouds,” are used to protect the Metal Bellows Expansion Joints from any external elements which might cause concern.

In sum, the appropriate use of Metal Bellows Expansion Joints is critical to the operating “up-time” of any significant piping system. Operations, production and, ultimately, profit are tied to the smooth and seamless flow of media through the intricate, and often unseen, “highway” of fluid transmission, whether liquid, gaseous, super-heated or super-cooled. “Forewarned is forearmed” is no cliche; either prepare or repair.

Metal Bellows Expansion Joints – Control your Heat, Movement and Pressure

Metal Bellows Expansion Joints – Control your Heat, Movement and Pressure

Piping systems are ubiquitous to heavy industrial markets. If there is fluid or gas movement, be it in the petrochemical, electric power supply, paper and pulp or a variety of OEM industries, optimal operation and “up-time” require state-of-the art piping systems to keep your plant competitive, or better, ahead of the curve. You know your business, and you know that in order to be profitable, your system must run at maximum efficiency. Metal Bellows Expansion Joints allow you to control fluid movement and containment in your system under a wide variety of pressures, thermal expansion and contraction, pulsations, vibration, equipment movement and convoluted routing requirements.

Typically, the key component of an expansion joint is the Metal Bellows element. Flexibility is paramount in containing the media and the pressure inherent in the system. Metal Bellows Expansion Joints, thin-walled, corrugated membranes, provide this flexibility.

An excellent solution is the use of punch formed, (expanded mandrel), manufactured Metal Bellows, followed by finish rolling. Rectangular metal sheets are sheared and rolled into a tube, which is then weld-mated using no filler metal. This longitudinal seam weld is then “plannished” to match the parent material thickness. “Bellows,” of course, implies convolutions. Once the welding is complete, and testing to tolerance performed, the convolutions are individually punched, drawing material from the top and bottom of the tube, thus creating consistency in the thickness of the Bellows material. Finally, the required “U” shape of the Bellows is implemented through the use of rollers. The Bellows are then trimmed, and ready for installation of attachment ends.

To assure the best performance of Metal Bellows Expansion Joints, the design, quality assurance, and manufacturing practices should be in compliance with EJMA, ASME Section VIII and IX, ANSI B31.1, B31.3 and other major industry standards such as UOP.

The Metal Bellows Expansion Joints may experience one or a combination of axial, angular, lateral, or twisting movement. Depending on system requirements, a variety of unrestrained and/or restrained assemblies, may be utilized. Unrestrained Assemblies include the following:

* Single Joint Assemblies: a single Metal Bellows welded to either a flange or pipe end.
* Universal Expansion Joint Assemblies: the connection of two pipe end or flange bellows with a center spool piece. This provides more flexibility with respect to axial, and angular movement.
* Externally Pressurized Expansion Joints: line pressure acts externally on the bellows component through use of a pressure chamber. More convolutions can be used to control axial movement, and alleviate concerns of bellows instability.

Four extremely effective Restrained Metal Bellows Expansion Joint Assemblies lead the pack:

* Tied Single Bellows Assemblies: a combination of the Single Bellows Assembly with tie rods, increasing system design flexibility.
* Tied Universal Assemblies: like Universal Assemblies, these limit lateral offset and angular movement by utilizing tie rods to absorb pressure thrust.
* Hinged Bellows Assemblies: angular movement is limited to one plane. Two or three Hinged Bellows Assemblies may be employed to handle large amounts of expansion in high pressure piping situations.
* Gimbal Bellows Assemblies: allow angular movement in all planes, while absorbing pressure thrust and twisting movement. When used in conjunction with a Single Hinged unit, these are particularly suited to maximize absorption in multi-planer piping systems.

While an in-depth discussion is beyond the scope of this article, a variety of options and accessories are available, and often necessary, to complete the installation of Metal Bellows Expansion Joint Assemblies. Briefly, these include the following:

* Ties rods: attach to an Expansion Joint assembly to mitigate pressure loads, as well as ancillary forces such as dead weight.
* Limit rods: a “fail-safe” addition which addresses the situation of occasional anchor overload or system malfunction which could cause bellows expansion beyond tolerance.
* Liners: internal sleeves used to protect the internal surface of the metal bellows from media which may compromise its integrity.
* Purge Connections: used in tandem with Liners, keep the bellows within high temperature tolerance conditions, such as oil industry applications.
* Covers: are used to protect the Metal Bellows Expansion Joints from any detrimental external elements.
* MAIN ANCHORS: resist the effects of all forces acting upon them, including pressure thrust, bellows spring resistance, frictional resistance of pipe guides, and inertial forces at bends and elbows.
* INTERMEDIATE ANCHORS: used to divide a long pipe run into shorter individual expanding sections.
* DIRECTIONAL ANCHORS: permit movement in one direction only.
* PIPE ALIGNMENT GUIDES: control thermal expansion in the system so that the movement applied to the bellows assembly is axial only.

As an example, if two expansion joints of different pipe diameters are used in the same section of pipe, such as a line containing a reducer, the pressure thrusts are no longer equal. In this case, the anchor dividing the expansion joints must be a main anchor designed to withstand the difference in pressure thrust generated by the different size Metal Bellows Expansion Joints.

Piping your media to the desired destination is essential to the success of your business; control the heat, movement and pressure on your operation with the appropriate use of Metal Bellows Expansion Joints, and you control the heat, movement and pressure on yourself.

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