scope:

This recommended practice covers the minimum requirements for the inspection and repair of special purpose rotating equipment rotors, bearings and couplings used in petroleum, chemical, and gas industry services.

This recommended practice is separated into 7 specific chapters. Chapters 2 through 7 are to be used separately from each other and in conjunction with Chapter 1. Refer to Chapter 1, Section 2 for the process used to overhaul and refurbish a rotor.

Tutorial Discussion: The document covers equipment manufactured to the requirements of API 612 Special Purpose Steam Turbines, API 613 Special Purpose Gears, API 617 Special Purpose Centrifugal Compressors, API 619 Special Purpose Rotary Positive Displacement Compressors, API 671 Special Purpose Couplings, and Hot Gas Expanders used in FCCU Power Recovery and Nitric Acid Services.

Note: A bullet (•) at the beginning of a paragraph indicates that either a decision is required or further information is to be provided by the owner. This information should be indicated on the appropriate data sheets; otherwise it should be stated in the quotation request or in the order. 

The basis of repair recommendations shall be to return dimensions required for spare parts interchangeability to the latest design fits and clearances and produce a safe reliable rotating element capable of at least 5 years of uninterrupted operation.

Note: Returning these dimensions to the latest design fits and clearances will allow the repair to:

a. Maintain interchangeability with other units.

b. Use existing spare parts.

c. Eliminate errors in manufacturing future spare parts that could be caused by undocumented dimensional changes.

d. Maintain its critical speed margins and torque transmission capabilities.

Notes:

1. Small bearing clearance changes can move rotor critical speeds and changes in shrink fits can adversely affect rotor dynamics.

2. The latest design fits and clearances may not be as originally designed by the original equipment manufacturer (OEM), since rerates and/or upgrades may have been incorporated into the machine design. 

Components manufactured for the repair shall be designed and constructed for a minimum service life of 20 years and at least 5 years of uninterrupted operation and in accordance with the latest API standards and Appendix K. Use of previously manufactured components (surplus, etc.) and their acceptance criteria should be mutually agreed upon by all parties involved. 

Unless otherwise specified, the repair shop (vendor) shall assume order responsibility.