Rotor Repair

Downstream Segment

API RECOMMENDED PRACTICE 687 FIRST EDITION, SEPTEMBER 2001

REAFFIRMED: JANUARY 2009

SPECIAL NOTES

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Copyright © 2001 American Petroleum Institute

FOREWORD

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to the standardization manager, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.

iii

CONTENTS

CONTENTS CHAPTER 1

Page

CHAPTER 1 ROTOR REPAIR 1-1

CHAPTER 2 SPECIAL PURPOSE CENTRIFUGAL COMPRESSORS 2-1

CHAPTER 3 SPECIAL PURPOSE AXIAL COMPRESSORS 3-1

CHAPTER 4 SPECIAL PURPOSE STEAM TURBINES 4-1

CHAPTER 5 SPECIAL PURPOSE GEARS 5-1

CHAPTER 6 SPECIAL PURPOSE EXPANDERS 6-1

CHAPTER 7 POSITIVE DISPLACEMENT ROTARY SCREW TYPE COMPRESSORS 7-1

CHAPTER 1—ROTOR REPAIR

CONTENTS CHAPTER 1

Page

1. SCOPE/DEFINITION/REFERENCE STANDARDS 1-1

   1. Scope 1-1

   2. Alternative Procedures 1-1

   3. Conflicting Requirements 1-1

   4. Definition of Terms 1-1

   5. Referenced Publications 1-2

   6. Statutory Requirements 1-4

   7. Unit Responsibility 1-4

2. PROCESS FOR OVERHAULING AND REFURBISHING A ROTOR 1-4

   1. General 1-4

   2. Typical Sequence of Events 1-4

   3. Owner Supplied Information 1-5

   4. Initial Scope of Inspection 1-5

   5. Upgrade Alternatives 1-5

   6. Developing the Scope of Repair 1-5

3. SELECTION OF A REPAIR SHOP 1-6

   1. General 1-6

4. COMMUNICATION 1-6

   1. General 1-6

   2. Meetings 1-6

   3. Electronic Drawing and Data Transmittal 1-6

   4. Post-Shipment Review 1-6

5. TRANSPORT TO VENDOR’S SHOP 1-7

   1. General 1-7

6. RECEIVING INSPECTION 1-7

   1. Receiving of Rotor 1-7

   2. Receiving Inspection 1-7

7. INSPECTION OF ASSEMBLED ROTOR, PHASE I 1-7

   1. General 1-7

   2. Rotor Inspection 1-7

8. INSPECTION METHODS AND TESTING 1-9

   1. General 1-9

   2. Component Inspection 1-9

9. REPAIR PROCESSES AND NEW COMPONENT MANUFACTURE 1-11

   1. General 1-11

   2. Shaft Restoration 1-11

   3. Coupling Shaft End 1-12

   4. Thrust Collars 1-12

   5. Shaft Sleeves and Spacers 1-12

   6. Radial Runouts 1-12

   7. New Component Manufacture. 1-13

      Page

10. ROTOR ASSEMBLY AND BALANCING 1-13

    1. General 1-13

    2. Low Speed Component Balancing 1-13

    3. Low Speed Assembly Balancing 1-14

    4. Residual Unbalance Testing and Installation of Trim Parts 1-16

    5. Balancing Equipment And Documentation 1-16

    6. High Speed (At Speed) Balance 1-16

11. PREPARATION FOR SHIPMENT AND STORAGE 1-18

    1. General 1-18

    2. Containers 1-18

    3. Rotor Supports 1-18

    4. Packing 1-19

12. DOCUMENTATION 1-19

    1. General 1-19

    2. Proposals 1-19

    3. Contract Data 1-19

    4. Document Retention 1-19

APPENDIX A PROCEDURE FOR DETERMINATION OF RESIDUAL UNBALANCE 1-21

APPENDIX B NON-DESTRUCTIVE EXAMINATION METHODS 1-29

APPENDIX C MAIN DRIVE COUPLINGS 1-37

APPENDIX D RESTORATION METHODS (OVERVIEW) 1-49

APPENDIX E FLUID FILM BEARINGS 1-55

APPENDIX F TOTAL INDICATOR READING 1-63

APPENDIX G VENDOR DATA DRAWING REQUIREMENTS (VDDR) 1-69

APPENDIX H AUDITORS CHECK LIST 1-73

APPENDIX I SELECTION OF A REPAIR SHOP CHECK LIST 1-85

APPENDIX J SHIPPING CONTAINERS 1-105

APPENDIX K QUALITY/MANUFACTURING PLAN 1-111

APPENDIX L ANTI-FOULING/CORROSION RESISTANT/PERFORMANCE IMPROVEMENT COATINGS 1-127

APPENDIX M EXAMPLES OF BEARING DAMAGE 1-133

Figures

1.A-1 (Blank) Residual Unbalance Work Sheet 1-23

1.A-2 (Blank) Residual Unbalance Polar Plot Work Sheet 1-24

1.A-3 Sample Residual Unbalance Work Sheet for Left Plane 1-25

1.A-4 Sample Residual Unbalance Polar Plot Work Sheet for Left Plane 1-26

1.A-5 Sample Residual Unbalance Work Sheet for Right Plane 1-27

1.A-6 Sample Residual Unbalance Polar Plot Work Sheet for Right Plane 1-28

Page

1.B-1 Steps in Liquid Penetrant Inspection 1-30

1.B-2 Principles of Magnetic Particle Inspection 1-32

1.B-3 Equivalent Hardness Table 1-35

1.C-1 Hub Dimensional Measurements. 1-41

1.C-2 Axial Pull-Up Tapered Coupling Hubs for 0.001 in. (I) per in.

Diameter Interference 1-45

1.E-1 Preload Variations 1-57

1.E-2 Stack Height Check 1-59

1.F-1 Typical Horizontal Dial Test Indicator 1-63

1.F-2 Proper Positioning of Contact Stylus 1-64

1.F-3 Inclination Error 1-64

1.F-4 Roundness Measurement 1-65

1.J-1 Commercial Shipment Boxing 1-107

1.J-2 Steel Container 1-107

1.J-3 Commercial and Export Boxing, 905 Kg (2000 lbs) through

4530 Kg (1000 lbs) 1-108

1.J-4 Export Shipment Boxing, 4530 Kg (10,000 lbs) through

13,600 Kg (30,000 lbs) 1-108

1.J-5 Commercial and Export Boxing, 13,600 Kg (30,000 lbs) and Over 1-109

1.L-1 Coating to Resist Corrosion and Fouling Below 260°C (500°F) 1-128

1.L-2 Coating to Resist Corrosion and Fouling Between 260°C (500°F)

and 565°C (1050°F) 1-129

1.L-3 Aerodynamically Smooth Coating to Resist Corrosion and Fouling

Up to 565°C (1050°F) 1-130

1.M-1a Thrust Shoe Surface Abrasion 1-135

1.M-1b Concentric Scoring of Thrust Pad 1-136

1.M-1c Scoring of Pad 1-136

1.M-2a Tin Oxide Damage 1-137

1.M-2b Tin Oxide Damage 1-137

1.M-3a Thermal Ratcheting 1-138

1.M-3b Overheating, Oil Additives Plated Out 1-139

1.M-3c Overheating and Fatigue at Joint 1-139

1.M-3d Cracking of Pad Due to Operation at Excessively High Temperatures 1-140

1.M-3e Cracking and Displacement of Pad Due to Overheating Under

Steady Conditions 1-140

1.M-3f Thermal Ratcheting Due to Thermal Cycling Through Excessive

Temperature Range In Service 1-141

1.M-4a Stray Shaft Currents/Electrical Pitting (Frosting) 1-142

1.M-4b Fine Hemispherical Pitting and Scoring of Bearing 1-143

1.M-4c Stray Shaft Currents/Electrical Pitting (Frosting) Journal Bearing 1-144

1.M-5a Edge Load Pivoted Shoe Showing Babbitt Mechanical Fatigue 1-145

1.M-5b Edge Load Journal Shell with Babbitt Mechanical Fatigue 1-146

1.M-5c Babbitt Fatigue in a Thin Thrust Plate 1-147

1.M-5d Babbitt Fatigue Cracking 1-148

1.M-5e Babbitt Fatigue Cracking 1-149

Page

1.M-6a Thrust Shoe Cavitations Damage in Babbitt Face 1-150

1.M-6b Thrust Shoe Cavitation Towards Outside Diameter 1-151

1.M-6c Cavitation Damage on Outside Diameter of Collar 1-152

1.M-6d Modification of Groove to Limit or Reduce Cavitation Damage 1-153

1.M-7a Bearing Wiped Due to a Barreled Journal 1-154

1.M-7b Uneven Wear of Bearing Due to Misalignment 1-155

1.M-8a Compressor Bearing with Formation of “Black Scab” 1-156

1.M-8b 13% Cr. Journal Running in Bearing Shown in Figure 1.M-7a

Showing Severe “Machining” Damage 1-157

1.M-8c ”Black Scab”—Wire Wooling—Formation on Thrust Pad 1-158

Tables

1.8-1 Generalized NDE Acceptance Criteria 1-10

1.C-1 Minimum Contact 1-42

1.D-1 Typical Properties of Various Thermal Spray Processes 1-51

1.E-1 Lift Check Correction Factor 1-59

1.L-1 Coating Application Summary 1-131

1.L-2 Relative Comparison of Coating Capabilities 1-132

Chapter 1—Rotor Repair

1. Scope/Definition/Reference Standards

   1. SCOPE

      1. 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 Chap- ter 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 Compres- sors, API 619 Special Purpose Rotary Positive Dis- placement 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 indi- cated on the appropriate data sheets; otherwise it should be stated in the quotation request or in the order.

      2. 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 reli- able rotating element capable of at least 5 years of uninter- rupted operation.

         Note: Returning these dimensions to the latest design fits and clear- ances will allow the repair to:

         1. Maintain interchangeability with other units.

         2. Use existing spare parts.

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

         4. 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.

      3. Components manufactured for the repair shall be designed and constructed for a minimum service life of 20

         
         

         1-1

         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.

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

1. ALTERNATIVE PROCEDURES

   The vendor may offer alternative procedures and designs. (See Chapter 1, paragraph 2.5 for proposal requirements).

   Note: Any exception to this recommended practice shall be clearly stated in the proposal as required by Chapter 1, paragraph 12.2.

   
   

2. CONFLICTING REQUIREMENTS

   In case of conflict between this recommended practice and the inquiry, the inquiry shall govern. At the time of the order, the order shall govern.

   
   

3. DEFINITION OF TERMS

   The terms used in this recommended practice are defined in 1.4.1 through 1.4.28.

   1. almen strips: Metallic strips used to determine the intensity of peening.

   2. calibration: The set of operations which establish, under specified conditions, the relationship between values indicated by a measuring instrument, or measuring system, or values represented by a material measure, and the corre- sponding known values of a standard.

      Notes:

      1. The results of calibration permit the estimation of indication errors of the measuring system, material measure or the assignment of values to marks on an arbitrary scale.

      2. The results of calibration may be recorded in a document some- times called a calibration certificate. Calibration method is a defined technical procedure for performing a calibration.

   3. hydrodynamic bearings: Bearings that use the principles of hydrodynamic lubrication. The bearing surfaces are oriented so that relative motion forms an oil wedge, or wedges, to support the load without shaft-to-bearing contact.

   4. indications: A response or evidence of a discontinu- ity that requires interpretations to determine its significance.

   5. “J” strips: Thin rotating labyrinth strips held in position by caulking or prick punching to the shaft or sleeve to provide pressure breakdown. These may also be referred to as “L” strips or “T” strips.