99 Diseases of Pressure Equipment: Vibration Fatigue

Few of us have not experienced or heard about vibration fatigue (cracking) failures, especially around pumps and compressors. Typically small branch connections, equalizer lines, vents and drains are susceptible, especially if they are screwed connections. Such failures have often led to safety and reliability events because of the sudden release of flammable hydrocarbons. Typically the vibration is detectable or known to operators, so their knowledge of the consequences of "living with vibrations" is key to prevention. Operators should be encouraged to report vibrations to engineers and inspectors so that steps can be taken to mitigate the cause of the vibration. There are several design and operating steps that can be taken to minimize vibration, and therefore prevent vibration fatigue failures. Often adding supports, stiffening gussets, anchors, or dampeners can help. Sometimes shifting the operating conditions of the machine is necessary to get out of or reduce the vibration regime. Inspection cannot be relied upon to find vibration fatigue cracks before failure. Though it is possible you can find cracks with surface NDE techniques, most often the time from cracking onset to failure is too short for inspection to be relied upon. So, once again, operator knowledge is key to prevention.

Do your operators and others in the field routinely report vibrations that might lead to fatigue failure if unattended to?