Metal expansion joints are installed in pipe systems, gas systems, water treatments and can be used to run electrical wire to prevent damage caused by thermal growth, vibration and other mechanical forces. There is a large variety of designs, but one particular metal, stainless steel, is used the most. Stainless steel expansion joints prevent vibration, thermal movement, and noise. As such, they offset problems and allow expansion in piping systems.
Incorrectly installing an expansion joint leads to leakage. Most incorrect installation is loose bolts and where the flanges meet. If the leak is up by or around the flanges, have it replaced immediately. If it is by the bolts, call a professional to tighten them.
Failure to Place Anchors
Anchors keep the pipe pressurized, and are to be placed 30 inches from the expansion joint. Without anchors, pressure generated movement will expand the compensation device to its maximum length and any thermal changes will be directed in the path of least resistance.
Most defects in welding are incomplete penetration, lack of fusion, undercutting, and porosity. Incomplete pressure is when two beads do not penetrate the complete thickness of the base plate. Lack of fusion or (cold lapping) occurs when there is no fusion between the weld metal and the surfaces of the base plate. Common cause of lack of fusion is poor welding technique.
Undercutting, on the other hand, is where a groove appears in the metal, and is also attributed to the lack of welding technique. Porosity is excessive shielding gas flow. Longitudinal, not as common, can be one of two types: hot cracks and cold cracks. The former occurs when the welding bead is between the melting stage and solid stage (when it is mushy).
Thermal expansion is the tendency of matter to change in shape, area, and volume in response to a change in temperature through heat transfer. This occurs when there are no expansion joints or anchors. Having an expansion joint with anchors keeps the piping sturdy so that no thermal expansion can occur.
Too much pressure build-up can cause the expansion joints to fail. This is usually caused by incorrect installation, like when anchors placed too close to the expansion joint or there are no anchors at all. Sometimes, the pipe does not have an expansion joint which causes the piping to crack or break in different areas.
Pipe Pressure on Itself
This occurs when no expansion joint is installed, since the pressure is shouldered the pipe system alone—and it is a lot of pressure for pipes. Without expansion joints you will have several problems, all similar to the ones seen with an expansion joint. There's nothing to release pressure of thermal expansion or to keep the pipe from breaking.
Corrosion is caused by the improper material used for the piping system. Whether its water, electricity or gas, without the correct expansion joint for that element, over time the expansion joint will slowly crumble until there is nothing left. This will leave you with a break or leak somewhere along the pipe.