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The failure mode of bellows could be any of a variety of things including erosion, corrosion, cyclic fatigue or thermal creep at elevated temperatures.

Failed expansion joint
Universal Metallic Expansion Joint from Competitor with Squirm Damage

What is the failure mode of bellows?

July 30, 1990

The failure mode of bellows could be any of a variety of things including erosion, corrosion, cyclic fatigue or thermal creep at elevated temperatures.

Failed expansion joint
Universal Metallic Expansion Joint from Competitor with Squirm Damage
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When there is an axial movement, the in-line bellows will start compressing and the balancing bellows will extend and vice versa. Both bellows will be moving.

In line pressure balanced expansion joint diagram
In-line pressure balanced expansion joint diagram

Regarding the operating temperature, we design metal pipe expansion joints up to 2000° F with refractory and 1000° F to 1500° F without refractory.

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Metallic Expansion Joint

Toroidals  can be used but not often. Most exchanges use normal thin-wall expansion joints or thick-wall expansion joints fabricated from flanged and flued heads.

72 inch thick wall expansion joint for a sulfuric acid plant
72″ inch thick wall pipe expansion joint

The weight of the units is self-supporting but the additional weight of the piping, elbows etc. in the field will not be supported by the expansion joint.

55 inch double gimbal expansion joint for a reactor overhead line
Gimbal pipe expansion joint

Yes, this is one of the expansion joint functions

No, it is the total of the spring rates of all three bellows.

36 pressure balanced elbow expansion joints
36″ Pressure Balanced Elbow Pipe Expansion Joint

 

The number of expansion joints used in a pipe depends on the length of the pipe, the pressure, the temperature, and the size. Upon knowing these design conditions, we can inform you of the number of expansion joints the pipeline requires.

An expansion joint is used to absorb dimensional changes, such as those caused by thermal expansion or contraction of a pipeline, duct, or vessel.

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High Temperature Fabric Expansion Joint Designed for an Exhaust Duct

The expansion joint used for fuel oil and fuel gas applications depends on the movement and design conditions of the particular application within the plant.

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Fabric Expansion Joints

The spring rate is equal to the spring rate of both flow bellows plus the spring rate of the balancing bellows.

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Elbow Pressure Balanced Pipe Expansion Joint

Expansion joints are needed to absorb thermal movement when piping flexibility will not solve the problem.

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92″ Double Hinged Reinforced Expansion Joint for Water Service

Expansion joints are required anywhere throughout the plant where thermal expansion must be absorbed. One example where expansion joints may be used in a power plant would be on piping running to power turbines or condensers.

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Tied Universal Expansion Joints for a Power Plant in Texas

Using expansion joints in piping depends upon the configuration of the piping where you will place the expansion joint to absorb thermal expansion or contraction.

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Fabric Expansion Joint Used in a Piping System

Duct work assemblies can include fabricated elbows, tees, straight sections of duct work, fabric or metallic expansion joints and can be rectangular or round.

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Duct work and expansion joint assembly.

It is recommended that all expansion joints include liners in order to protect the bellows from the internal flow environment.

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Universal Expansion Joint with Stainless Steel Liner

A movement guide controls the thermal motion of the piping system into the bellows

Expansion couplings are used mainly to connect two pieces of pipe together.

 

Usually, the liner material can be the same as the system pipe material, such as carbon steel, with liner thicknesses of 1/8-inch and greater depending upon flow rate and diameter.

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50 Universal Expansion Joints with Liners

The growth of an expansion joint bellows is restrained with the use of limit rods.

Accessories limit rod
Limit Rods Shown on a Universal Expansion Joint