API 674 Pump Pulsation Studies
Pulsations and mechanical response studies conforming to API 674
The nature of a reciprocating pump means that pressure fluctuations will be developed in the connecting piping. The amplitude and frequency of these fluctuations depend on the characteristics of the pump. Should these pulsations be excessive it is possible that mechanic and acoustic resonance modes within the piping are excited.
If an acoustic mode is excited then pressures exceeding the design pressure of the piping, or problems in downstream equipment, may result. If a mechanical resonance mode is excited, the piping is likely to vibrate, and fatigue failure and excessive loads on the supporting structure become a concern.
The industry standard design code API 674 provides guidelines to avoid pulsations from a reciprocating pump having a detrimental impact on a system. By conducting our pulsation and mechanical response studies according to this code, Dynaflow Research Group (DRG) can establish if pulsations are a potential issue for your system.
Pulsation Studies
DRG is adept at conducting a pulsation study of your piping system or pump skid to determine if excessive pressure pulsations are to be expected. When conducting a pulsation study we make use of our own commercially available software package BOSpulse.
BOSpulse has been specifically developed for conducting pulsation analyses. It has the option to check for conformance with API 674 built-in and features a reciprocating pump model to calculate the pressure pulsations generated by a specific pump geometry.
If a system does not conform to API 674, DRG always offers practical recommendations for how to avoid excessive pressure pulsations and achieve conformance. Often this requires the introduction or modification of pulsation dampeners or re-routing the piping to alter a resonance mode.
Mechanical Response Analysis
Any structure or piping system will have a number of mechanical resonance (natural) frequencies. By identifying these resonance modes, it can be confirmed that there is no possibility for these to be excited by the pulsations caused by the reciprocating pump.
Using piping modeling software, DRG can conduct a mechanical response study to determine which of these resonance modes will be excited and if the resulting stresses could lead to rupture or fatigue failure of the piping.
Our expertise in piping design means that we can propose practical and realizable solutions to remove any critical resonance modes and ensure that the system conforms to the applicable piping design code.
Solving Issues In The Field
Pulsation problems, such as excessive pipe vibrations or the rupture of a branch connection, can occur during operation. Usually, these occur within systems for which no pulsation analysis had been conducted. However, even if the relevant design codes were satisfied at the design stage, installation faults or unanticipated operating scenarios can lead to problems.
To solve problems in the field, DRG works closely with the on-site staff. Our experts will assess the extent of the problem and, if it is possible to replicate the vibrations, DRG can take measurements to determine their amplitude and frequency. The results of the inspection and any measurements are then used by DRG to identify the cause of the vibration and to propose a solution.
