Page 466 - Compression Machinery for Oil and Gas

446 SECTION III Applications

techniques, and a modal analysis will be performed to predict the MNFs of the
compressor system. A forced response analysis will be performed to estimate
peak stress and vibration levels to ensure acceptability. Piping and restraint sys-
tem modifications will be made in order to avoid coincidence between the
MNFs of the piping and frequencies of residual pulsation energy. This analysis
is discussed in the API 618 and API 688 standards.

Field Testing
On-site field testing of a compressor system is often performed to confirm the
system is operating within the design limits, to troubleshoot an existing concern,
or to collect data for use in validating or calibrating a computational model.
During a field test, instrumentation will be installed on the machinery and
piping system at key locations to measure a variety of potential data such as
pulsation, vibration, strain, temperature, pressure, torsional vibration, noise,
impact data, performance testing, etc. This data can then be used to determine
the severity and frequency content of any pulsation, vibration, etc., to evaluate
the concerns. The data is typically collected at a variety of static operating con-
ditions, including various operating speeds and load steps, as well as dynamic
(transient) conditions to determine how the symptoms may vary or correlate
with various operating conditions. A data acquisition system provides an inter-
face between the hardware and software and allows signal conditioning, dis-
play, recording, and analysis of the measurements.

References
[1] GMRC, GMRC Guideline for High Speed Reciprocating Compressor Packages, Appendix 3.1,
2013.
[2] M. Hinchliff, S. Greenfield, W. Bratek, A discussion of the various loads used to rate recip-
rocating compressors, GMRC Gas Machinery Conference, 2014.
[3] Brun, K. and Kurz, R., 2010, “Analysis of the effects of pulsations on the operational stability
of centrifugal compressors in mixed reciprocating and centrifugal compressor stations”, J. Eng.
Gas Turbines Power, vol. 132, n 7.
[4] K. Brun, S. Simons, R. Kurz, Impact of reciprocating compressor pulsations on the surge
margin of centrifugal compressors, J. Eng. Gas Turbines Power 139 (8) (2016). ASME;
GTP-16-1269.
[5] API 521, Pressure-Relieving and Depressuring Systems, sixth ed., 2014.
[6] Energy Institute (Ed.), Guidelines for the Avoidance of Vibration Induced Fatigue Failures in
Process Pipework, second ed., Energy Institute, London, 2008.
[7] R. Blevins, Flow Induced Vibration, second ed., Krieger Publishing Company, Malabar,
Florida, 2001. 407 p.
[8] T. Allison, N. Evans, N. Poerner, An efficient finite element analysis method for acoustic
induced vibration analysis, Proceedings of Inter-Noise, New York, NY, Institute of Noise Con-
trol Engineering, 2012.
[9] T. Allison, N. Evans, Acoustically induced vibration in gas piping systems, Proceedings of Gas
Machinery Conference, Albuquerque, NM, 2013.