Piping Vibration Design Considerations

1 Static Design
2 Dynamic Design
3 Recommendations for Use

1 Static Design

Static design involves thermal effects on the piping system as well as pressure, weight, and other applicable loads (eg, seismic). The design methodology and approach for this service includes the following features:

Accurate assumptions in piping models
Wood understands that actual pipe support stiffnesses vary dramatically depending on the application. Based on our field and design research, our piping support stiffnesses are more accurate compared to traditional approaches that assume “rigid” supports. Improved accuracy means better designs that avoid significant project design inefficiencies involved with solving problems (that are not there in reality), or missing critical risk areas
Consideration of vibratory loads as well as thermal loads (see below – dynamic design)
Use of specialty restraints and pipe clamps that effectively achieve requirements for both vibration and thermal growth design aspects
Ability to support other design requirements (buried pipe, glass reinforced epoxy, flexible pipe, etc.)

2 Dynamic Design

There are many applications where dynamic concerns should be addressed in the design stage by investigating both normal operating and transient cases. Areas to consider include:

Pressure pulsation and vibration affecting the piping near reciprocating compressors and pumps
Centrifugal compressor surge control dynamic simulation and evaluation
Piping vibration due to flow-induced vibration (FIV), acoustic-induced vibration (AIV), flow-induced turbulence (FIT), etc.
Transient events in the system causing vibration, pressure surge (water or fluid hammer), cavitation, and pipe collapse due to valve swings, emergency shut downs, PSV lifting, and other transients in gas or liquid systems
Excitation of transverse acoustical modes and shell modes of the pipe by vane-passing pulsations (also called shell transverse acoustical vibration).

3 Recommendations for Use

Engingeering Analysis	System	When Required
Flow-Induced turbulence (FIT) Analysis	All fluids	High flow systems with flexible and infrequent supports
Machinery and Equipment Nozzle Load Analysis	All fluids	Machinery and equipment with low allowable nozzle loads
Piping Stress	All fluids	High temperature/pressure variation
Small-Bore Connections (SBC) Analysis	All fluids	All connections not reinforced or braced
Shell Transverse Acoustical (STA) Analysis	All fluids (but typically gas systems)	Thin walled pipe or vessels near compressors and pumps
Compressor Surge Dynamic Simulation	Centrifugal compressor systems	Low inertia, high pressure ratio, complex systems
Acoustic-Induced Vibration (AIV) Analysis	Gas systems only	Pressure reducing devices like valves and orifice plates
Flow-Induced Vibration (FIV) Analysis	Gas systems only	High flow systems with dead legs
Transient Vibration Analysis (gas systems)	Gas systems only	Blowdown or PSV releasing events, momentum changes
Cavitation/Flashing	Liquid systems only	Pressure reducing devices like valves and pumps
Water (or fluid) Hammer Analysis	Liquid systems only	Fast acting valves and emergency shutdown events
Pulsation and Mechanical Analysis	Reciprocating compressor/pump; Screw compressor	High pressure, high power, complex or critical systems

Wood's vibration dynamics and noise team is a specialist engineering consultancy that provides piping design engineering services, as well as field vibration analysis and troubleshooting.

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Piping Vibration Design Considerations

1 Static Design

2 Dynamic Design

3 Recommendations for Use

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