Facilities Vibration Analysis
Vibration analysis is important in oil and gas facilities because rotating and reciprocating equipment, pressure pulsations, flow disturbances, and transient operating events can generate cyclic dynamic loads in connected piping. Pump and compressor stations are particularly susceptible, with small-bore connections, instrument take-offs, drains, vents, and welded attachments often representing fatigue-sensitive locations. If vibration levels are not adequately controlled, repeated dynamic stresses can initiate fatigue cracking and potentially lead to loss of containment. The Energy Institute specifically identifies vibration-induced fatigue as an important integrity concern in process pipework and notes that welded joints and small-bore connections are among the most fatigue-sensitive locations.
- Assessment of piping connected to pumps, compressors, control valves, pressure-reducing devices, and other sources of dynamic excitation.
- Evaluation of small-bore connections and instrument branches susceptible to vibration-induced fatigue.
- Identification of potential resonance between excitation frequencies and piping or branch natural frequencies.
- Assessment of vibration associated with reciprocating pressure pulsations, mechanical excitation, flow-induced vibration, turbulence, and transient events. The Energy Institute guidance is intended for new designs, existing facilities, plant modifications, and situations where vibration concerns have been identified during operation.
- Evaluation of the effects of unsupported branch length, attached valve or instrument mass, connection geometry, and support stiffness on fatigue susceptibility. Energy Institute guidance notes that longer small-bore connections generally have lower natural frequencies and greater susceptibility to vibration-related problems.
- Development of practical mitigation measures such as support or bracing modifications, reduction of unsupported mass, shortening of small-bore connections, piping layout changes, or modification of the excitation source.
- Assessments may incorporate applicable requirements and guidance from CSA Z662, ASME B31.3, ASME B31.4, ASME B31.8, equipment-specific requirements, and the Energy Institute Guidelines for the Avoidance of Vibration Induced Fatigue Failure in Process Pipework.
