How Expansion Joint Systems Work

By: Anna Woodward

Expansion joint systems are an innovative alternative for pipes and pipelines. These joints can be used in the oil, paper, and petrochemical industries and in many others fields.

The diversity of expansion joints available for application is great. They are usually manufactured at standard dimensions and can reach from 1 to 200 inches in diameter; can withstand temperatures from minus 300 degrees F up to 4000 degrees F and can resist at full vacuum or 2000 psig.

The introduction of fabric expansion joints on the market completely revolutionized the way that engineers solve thermal expansion, corrosive and abrasive problems. These fabric joints can be used in different applications for turbines. With different fabric membranes and designs, extensions joints can easily be used for turbine exhaust applications (GTX). GTX are rather problematic applications that pose distinctive challenges concerning performance and resistance through time but which can now be more easily solved with the help of fabric joints.

Metal bellows are generally used in pipeline systems that connect pumps and vessels. The design of the folds in the metal bellow allows for greater axial, lateral, and angular movement. To increase the angular or lateral flexibility, ties, pivots and other trimmings can be added to a metal bellow. The life span of these devices is determined by the shape, material, degree to which the junction must be able to move, and of course, forces that are greater than the designed limits.

With the help of these bellows, flanged-end and fused-end expansion joints can be quite easily and quickly fabricated. Both universal and double expansion joints use two bellows.

Metal expansion joints are crucial components for pipeline technology. They are used to counterbalance length changes, which usually occur in pipelines from temperature changes. Besides this, they are capable of absorbing vibrations developed by pumps, engines, compressors or turbines. Depending on the situation, axial and lateral movement as well as angular movement can be compensated. Metal expansion joints offer a cost effective choice and enhance the productive life cycle of a pipeline system. Designed to last as long as the system; metal bellows reduce sealing problems and the large space needed with alternative expansion equipment.

Some of the most vital and complex categories of expansion joints manufactured are those used in FCCU (fluid catalytic cracking unit). The reason for the complexity is these expansion joints have to withstand extremely high temperatures (1400 degrees F) and pressures, extreme and aggressive environments and great movement conditions.

To ensure a good function of these systems, absolute attention and skill is mandatory in designing the bellows and hardware. All FCCU joints are specially designed for every application in which they are used because any failure during installation can be hazardous to personnel and extremely expensive to users. Accepted specifications offer the basis for the design of the bellows and joint hardware of the FCCU joints.

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