Introduction to Various Sections of Rotor Dynamics in American Petroleum Institute Standards (API) related to Centrifugal Machines

Rotating machines either compressor are pump are widely used to increase the pressure of process gas or fluid in all kind of oil and gas processing. The power of these rotating machines ranges from few kilo watts to hundreds of mega watts. And these pumps and compressors are by electric motors , steam turbines or gas turbines depending on the application. The driver and driven equipment are directly coupled by couplings and in some cases the by gear box and coupling depending on the application and range of operating condition, driven and driver speed difference. It forms a big train comprising of different rotating elements of driver , driven and coupling. These different rotating elements are supported at different points by bearings. The train length depends on power rating and application it may vary from less than a meter to close 30 or 40 meter in LNG train applications.

Vibration is always one of the major phenomena in Rotating machines. The rotating equipment engineers in manufacturing , service and engineering and field operation and maintenance shall aware about the basics of vibration problems and analysis in order to better tackle this problem in various stages of the project /machine operation.

The objective of this article is to list out various section of API (American Petroleum Institute) standards dealing with vibration analysis of centrifugal machines.

• API RP684 - This standard deals with the basics of Vibration and Rotor dynamic analysis. It describes about fundamentals and various terminologies of vibration analysis, balancing of Rotors etc.
• API 610 - In 11th edition of API 610 for Centrifugal Pumps Dynamic analysis of pumps is described in Section 6.9 and dynamics analysis related to individual pump types (OH,BB and VS) are described in Section 9.0. Also the methods of analysis is described in Annex I.
• API 611 - In 5th edition of API 611 General Purpose Steam Turbine dynamics analysis is described in Section 6.9 and Annex B.
• API 612 - In 7th edition of API 612 Special Purpose Steam Turbine dynamic analysis is described in Section 9.
• API 613 - Gear box - Section 2.6 describes about the dynamic analysis.
• API 616 - Gas turbines - Section 4.7 and Appendix D describes about dynamic analysis of rotors.
• API 617 - Centrifugal Compressor - In Part I - Section 4.8 and Annex C,D and E describes about the dynamic analysis of rotors.
• API 619 - Positive Displacement Compressors - Section 5.7 of rotor dynamic analysis describes about rotor dynamics.
• API 671 - Special Purpose Couplings - Section 8.12 describes about rotor dynamic analysis
• API 672 - Integrally geared compressors - Section 6.7 describes about rotor dynamic analysis
• API 673 - Centrifugal Fans - Section 6.7 and Annex D describes about rotor dynamic analysis

In my next article will write about the common approach used in dynamic analysis between the various section of API standards for Centrifugal machines.