Special-purpose Gears for Petroleum, Chemical, and Gas Industry Services

API STANDARD 613

SIXTH EDITION, JULY 2021

Special Notes

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Copyright © 2021 American Petroleum Institute

Foreword

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Suggested revisions are invited and should be submitted to the Standards Department, API, 200 Massachusetts Avenue, Suite 1100, Washington, DC 20001, standards@api.org.

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, Acronyms, Abbreviations, and Symbols 4

   1. Terms and Definitions 4

   2. Acronyms and Abbreviations 8

   3. Symbols 9

4. Unit Responsibility 10

5. Requirements 10

   1. Units of Measure 10

   2. Statutory Requirements 10

   3. Documentation Requirements 10

6. Basic Design 10

   1. General 10

   2. Rating 15

   3. Casings 22

   4. Casing Connections 25

   5. Gear Elements 27

   6. Dynamics 32

   7. Bearings and Bearing Housings 40

   8. Lubrication 44

   9. Materials 45

   10. Nameplates and Rotation Arrows 46

7. Accessories 46

   1. General 46

   2. Couplings and Guards 46

   3. Mounting Plates, Soleplates, and Sub-soleplates 47

   4. Controls and Instrumentation 47

   5. Piping and Appurtenances 48

   6. Special Tools 48

8. Inspection, Testing, and Preparation for Shipment 48

   1. General 48

   2. Inspection 49

   3. Testing 52

   4. Preparation for Shipment 59

9. Vendor's Data 62

   1. General 62

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Contents

Page

Annex A (informative) Special-purpose Gear Unit Datasheets 63

Annex B (informative) Bearing Temperature Limits 73

Annex C (informative) Material Specifications for Special-purpose Gear Units 75

Annex D (informative) Contract Documents and Engineering Design Data 77

Annex E (normative) Vendor Drawing and Data Requirements 82

Annex F (normative) Procedure for the Verification of Residual Unbalance 89

Annex G (informative) Gear Tooth Quality Inspection 95

Annex H (informative) Inspector’s Checklist 100

Annex I (informative) Special Considerations in Very High Speed Gears 104

Bibliography 113

Figures

1. Shaft Assembly Designations (for Parallel-shaft, Single-, and Double-helical

   One- and Two-stage Speed Increasers and Reducers) 14

2. Shaft Rotation Designations 14

3. Contact Stress Number, σHP, Carburized Steel 19

4. Allowable Bending Stress Numbers, σFP, Carburized Steel 21

5. Undamped Critical Speed Map 34

6. Train Lateral Guideline Diagram 35

7. Unbalance Placement 36

8. Critical Speed Separation Margins 37

9. Plot of Applicable Speed Range of Vibration Limit 39

10. Back-to-back Locked-torque Test (Typical) 58

1. Residual Unbalance Worksheet 92

2. Sample Residual Unbalance Worksheet for Left Plane (SI) 93

3. Sample Residual Unbalance Worksheet for Right Plane (USC) 94

1. Tooth Alignment (Lead) Modification of Helical Pinion 97

2. Tooth Alignment Helix (Lead) Modification of Double-helical Pinion 98

3. Profile Modification 99

1. Pitting May Lead to Tooth Fracture 104

2. Example of Tooth Scuffing 105

3. Example of Tooth Scuffing 105

4. Typical Rating Curve for Hardened and Ground Gearing 106

5. Region of Negative Sliding 107

6. An Example of Micropitting 107

7. Grinding Burns 108

8. Gray Scale 109

9. Nital Etching Used to Show Shade Comparison 109

10. Special Damage Criteria for High-speed Turbo Gear Rotors 111

11. An Example of a Heavily Varnished Gear Set 112

Tables

1. Symbols 9

2. Driver Trip Speeds 12

   vi

   Contents

   Page

3. Shaft Assembly Combinations 13

4. Minimum Gear Tooth Service Factors 16

5. Tooth Flank Pitting Derating Factor 18

6. Minimum Tubing Wall Thickness 23

7. Drain Connection Sizes 25

8. Maximum Severity of Defects in Castings 51

9. Casing Vibration Levels During No-load Running Test 55

1. Gear Unit Housings 75

2. Shafts, Pinions, and Gear Wheels 76

F.1 Trial Weight Multiplier vs NHP 90

Introduction

Users of this standard should be aware that further or differing requirements may be needed for individual applications. This standard is not intended to inhibit a gear vendor from offering, or the purchaser from accepting, alternative equipment or engineering solutions for the individual application. This may be particularly appropriate where there is innovative or developing technology. Where an alternative is offered, the gear vendor should identify any variations from this standard and provide details.

ANNEX A—Special-purpose Gear Unit Datasheets (informative). ANNEX B—Bearing Temperature Limits (informative).

ANNEX C—Material Specifications for Special-purpose Gear Units (informative). ANNEX D—Contract Documents and Engineering Design Data (informative).

ANNEX E—Vendor Drawing and Data Requirements (normative).

ANNEX F—Procedure for the Verification of Residual Unbalance (normative). ANNEX G—Gear Tooth Quality Inspection (informative).

ANNEX H—Inspector’s Checklist (informative).

ANNEX I—Special Considerations in Very High Speed Gears (informative).

This standard requires the purchaser to specify certain details and features. A bullet (•) at the beginning of a subsection or paragraph indicates that either a decision by, or further information from, the purchaser is required. Further information should be shown on the datasheets (see example in Annex A) or stated in the quotation request and purchase order.

In this standard, U.S. customary (USC) units are included in brackets for information.

Special-purpose Gears for Petroleum, Chemical, and Gas Industry Services

1. Scope

   
   

   This standard covers the minimum requirements for special-purpose, enclosed, precision involute gear single- and double-helical one- and two-stage speed increasers and reducers of parallel-shaft design for use in petroleum, chemical, and gas industry services. This standard is intended for gear units that are in continuous service without installed spare equipment. Gear sets furnished to this standard are considered matched sets.

   
   

   NOTE The purchase of a spare set of gear rotors or a complete gear unit does not mean that the gear unit in continuous service has an installed spare.

   
   

   This standard includes related lubricating systems, controls, instrumentation, and other auxiliary equipment. This standard is not intended to apply to gear units in general-purpose service, which are covered by API 677; to gears integral with other equipment, such as integrally geared compressors and expanders covered by API 617 or API 672; or to gears other than involute helical.

   
   

2. Normative References

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Standards referenced in the document are undated but refer to the specific editions referenced in this section.

ANSI 1/API Standard 614, Lubrication, Shaft-sealing and Oil-control Systems and Auxiliaries

API Standard 670, Machinery Protection Systems

API Standard 671, Special-purpose Couplings for Petroleum, Chemical, and Gas Industry Services

API Recommended Practice 684, Paragraphs Rotordynamic Tutorial: Lateral Critical Speeds, Unbalance Response, Stability, Train Torsionals and Rotor Balancing

API Recommended Practice 686, Machinery Installation and Installation Design, Second Edition, 2009 AGMA 927 2, Load Distribution Factors—Analytical Methods for Cylindrical Gears

ANSI/AGMA/ISO 1328-1 3, Cylindrical gears—ISO system of flank tolerance classification—Part 1: Definitions and allowable values of deviations relevant to flanks of gear teeth

ANSI/AGMA 2001-D04, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth (U.S. Units)

ANSI/AGMA 2101-D04, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth (Metric)

ANSI/AGMA 6001, Design and Selection of Components for Enclosed Gear Drives

ANSI/AGMA 6011-J14, Specification for High Speed Helical Gear Units

ANSI/AGMA 6025, Sound for Enclosed Helical, Herringbone and Spiral Bevel Gear Drives

1 American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, NY 10036, www.ansi.org.

2 American Gear Manufacturers Association, 1001 N. Fairfax Street, Suite 500, Alexandria, VA 22314-1587, www.agma.org.

3 International Organization for Standardization, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland, www.iso.org.

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