Expansion Joints Keep your Production Moving

By: Anna Woodward

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.

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