Generally a gasket is replaced when it suffers imminent damage as it acts as a fuse in a piping system. Damage can be caused by different factors such as:
- Water hammer: Increase in pressure due to change in speed in a fluid.
- Overpressure: Pressure above the normal working pressure of the system.
- Buckling by column: Rotation of a plane of one or more waves of a bellows.
- High temperatures: In the case of expansion joints, it is a temperature at which the material begins to lose physical properties.
- Torsion in systems: Any rotational movement that a joint receives is a cause of damage since the bellows are not designed to receive torque.
- Incompatibility of materials with the fluid: Inappropriate material for the fluid being worked.
- Poorly supported pipe: A pipe must be supported according to a standard and with technical specifications according to its behavior.
- The line without fixed points: Fixed points are a restriction in all senses, to direct the movement of a tube.
- Joints without tensioners: Tensioners (tie rod) limit the pressure reaction force in case there are no fixed points.
- Calculation reports outside of what is permissible: Values according to calculations of resistance and admissible stresses to determine loads.
- Poor joint selection for inadequate movement: Each expansion joint complies with a specific movement, which must be taken into account when selecting it.
- Very high frequencies: The very large amplitude of a frequency fatigues the bellows material, for this reason the maximum lateral movement must be reviewed.
In general, a correctly selected gasket will not cause problems and its useful life is extended by up to more than 10 years. A gasket has certain life cycles according to an EJMA calculation that is carried out at the time of its manufacture and is delivered to the client to make the change or maintenance projection.
If a process requires a change due to damage to the gasket, it is necessary to review and diagnose what caused the gasket to be damaged. This is done by taking a tour of the pipe in which it is installed, and a specific review of the operating conditions of the system. From this point, a flexibility study can be carried out to determine forces, moments, efforts and in this way give the pertinent recommendations.