Recommended Practice for Drill Stem Design and Operating Limits

API RECOMMENDED PRACTICE 7G SIXTEENTH EDITION, AUGUST 1998

EFFECTIVE DATE: DECEMBER 1, 1998

ERRATA: MAY 2000

ADDENDUM 1: NOVEMBER 2003

ADDENDUM 2: SEPTEMBER 2009

Recommended Practice for Drill Stem Design and Operating Limits

Upstream Segment

API RECOMMENDED PRACTICE 7G SIXTEENTH EDITION, AUGUST 1998

EFFECTIVE DATE: DECEMBER 1, 1998

ERRATA: MAY 2000

ADDENDUM 1: NOVEMBER 2003

ADDENDUM 2: SEPTEMBER 2009

SPECIAL NOTES

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API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005.

Copyright ? 1998, 2000, 2003 American Petroleum Institute

FOREWORD

This recommended practice is under the jurisdiction of the API Subcommittee on Stan- dardization of Drilling and Servicing Equipment.

The purpose of this recommended practice is to standardize techniques for the procedure of drill stem design and to de?ne the operating limits of the drill stem.

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 con?ict.

Changes from the previous edition are denoted with bars in the margins. The bars indicate

98 new content or major editorial changes. Changes to section numbers due to reformatting or minor editorial changes are not denoted with bars.

Suggested revisions are invited and should be submitted to the director of the Exploration and Production Department, American Petroleum Institute, 1220 L Street, N.W., Washing- ton, D.C. 20005.

This recommended practice shall become effective on the date printed on the cover but may be used voluntarily from the date of distribution.

iii

CONTENTS

Page

1. SCOPE 1

   1. Coverage 1

   2. Section Coverage 1

2. REFERENCES 1

3. DEFINITIONS. 1

4. PROPERTIES OF DRILL PIPE AND TOOL JOINTS. . . . . . . . . . . . . . . . . . . . . . . . . .3 03

5. PROPERTIES OF DRILL COLLARS 33

6. PROPERTIES OF KELLYS 33

7. DESIGN CALCULATIONS. 46

   1. Design Parameters 46

   2. Special Design Parameters 46

   3. Supplemental Drill Stem Members 46

   4. Tension Loading 46

   5. Collapse Due to External Fluid Pressure 50

   6. Internal Pressure 51

   7. Torsional Strength 51

   8. Example Calculation of a Typical Drill String Design—Based on

      Margin of Overpull 51

   9. Drill Pipe Bending Resulting From Tonging Operations 52

8. LIMITATIONS RELATED TO HOLE DEVIATION 53

   1. Fatigue Damage 53

   2. Remedial Action to Reduce Fatigue 54

   3. Estimation of Cumulative Fatigue Damage 58

   4. Identification of Fatigued Joints 58

   5. Wear of Tool Joints and Drill Pipe 58

   6. Heat Checking of Tool Joints 59

9. LIMITATIONS RELATED TO FLOATING VESSELS 59

10. DRILL STEM CORROSION AND SULFIDE STRESS CRACKING 61

    1. Corrosion 61

    2. Sulfide Stress Cracking 64

    3. Drilling Fluids Containing Oil 65

11. COMPRESSIVE SERVICE LIMITS FOR DRILL PIPE 67

    1. Compressive Service Applications 67

    2. Drill Pipe Buckling in Straight, Inclined Well Bores 67

    3. Critical Buckling Force for Curved Boreholes 78

    4. Bending Stresses on Compressively Loaded Drill Pipe in Curved Boreholes .79 11.5 Fatigue Limits for API Drill Pipe 96

1. Estimating Cumulative Fatigue Damage 98

2. Bending Stresses on Buckled Drill Pipe 101

1. SPECIAL SERVICE PROBLEMS 101

   1. Severe Downhole Vibration 101

   2. Transition from Drill Pipe to Drill Collars 108

12.3 Pulling on Stuck Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 09

1. Jarring 109

2. Torque in Washover Operations 109

3. Allowable Hookload and Torque Combinations 109

4. Biaxial Loading of Drill Pipe 110

5. Formulas and Physical Constants 110

6. Transition from Elastic to Plastic Collapse 110

7. Effect of Tensile Load on Collapse Resistance 110

8. Example Calculation of Biaxial Loading 110

1. IDENTIFICATION, INSPECTION AND CLASSIFICATION OF DRILL

   STEM COMPONENTS 112

   1. Drill String Marking and Identification 112

   2. Inspection Standards—Drill Pipe and Tubing Work Strings 112

   3. Tool Joints 122

13.4 Drill Collar Inspection Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 09

1. Drill Collar Handling Systems 124

2. Kellys 125

3. Recut Connections 126

4. Pin Stress Relief Grooves for Rental Tools and Other Short Term

Usage Tools 126

1. SPECIAL PROCESSES 127

   14.1 Drill Stem Special Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 03

   14.2 Connection Break-In 127

2. DYNAMIC LOADING OF DRILL PIPE 127

3. CLASSIFICATION SIZE AND MAKE-UP TORQUE FOR ROCK BITS 128

   APPENDIX A STRENGTH AND DESIGN FORMULAS . . . . . . . . . . . . . . . . . . . . . 133 03

   APPENDIX B ARTICLES AND TECHNICAL PAPERS 151

   
   

   Figures

   1–25 Torsional Strength and Recommended Make-up Torque Curves 20–32

   1. Drill Collar Bending Strength Ratios, 11/2 and 13/4 Inch ID 39

   2. Drill Collar Bending Strength Ratios, 2 and 21/4 Inch ID 40

   3. Drill Collar Bending Strength Ratios, 21/2 Inch ID 41

   4. Drill Collar Bending Strength Ratios, 213/16 Inch ID 42

   5. Drill Collar Bending Strength Ratios, 3 Inch ID 44

   6. Drill Collar Bending Strength Ratios, 31/4 Inch ID 45

   7. Drill Collar Bending Strength Ratios, 31/2 Inch ID 46

   8. New Kelly-New Drive Assembly 48

   9. New Kelly-New Drive Assembly 48

   10. Maximum Height of Tool Joint Above Slips to Prevent Bending

       During Tonging 53

   11. Dogleg Severity Limits for Fatigue of Grade E75 Drill Pipe 55

   12. Dogleg Severity Limits for Fatigue of S-135 Drill Pipe 56

   13. Lateral Force on Tool Joint 57

   14. Fatigue Damage in Gradual Doglegs (Noncorrosive Environment) 58

   15. Fatigue Damage in Gradual Doglegs (In Extremely Corrosive Environment) . . 58

   16. Lateral Forces on Tool Joints and Range 2 Drill Pipe 31/2 Inch, 13.3 Pounds

       per Foot, Range 2 Drill Pipe, 43/4 Inch Tool Joints 60

   17. Lateral Forces on Tool Joints and Range 2 Drill Pipe 41/2 Inch, 16.6 Pounds

       per Foot, Range 2 Drill Pipe, 61/4 Inch Tool Joints 60

   18. Lateral Forces on Tool Joints and Range 2 Drill Pipe 5 Inch, 19.5 Pounds per Foot, Range 2 Drill Pipe, 63/8 Inch Tool Joints 62

   19. Lateral Forces on Tool Joints and Range 3 Drill Pipe 5 Inch, 19.5 Pounds per

       Foot, Range 3 Drill Pipe, 63/8 Inch Tool Joints 62

   20. Delayed-Failure Characteristics of Unnotched Specimens of an SAE 4340 Steel During Cathodic Charging with Hydrogen Under Standardized Conditions 66

46–66 Approximate Axial Compressive Loads at which Sinusoidal Buckling is Expected to Occur 68–78

67a–74a Bending Stress and Fatigue Limits 80–94

67b–74b Lateral Contact Forces and Length 81–95

1. Hole Curvature Adjustment Factor To Allow for Differences in Tooljoint OD’s 97

2. Median Failure Limits for API Drillpipe Noncorrosive Service 99

3. Minimum Failure Limits for API Drillpipe Noncorrosive Service 100

78a Bending Stress for High Curvatures 102

78b Lateral Contact Forces and Length 103

79a Bending Stress for High Curvatures 104

79b Lateral Contact Forces and Length 105

80a Bending Stress for High Curvatures 106

80b Lateral Contact Forces and Length 107

1. Ellipse of Biaxial Yield Stress or Maximum Shear-Strain Energy Diagram After Holmquist and Nadai, Collapse of Deep Well Casing, API Drilling and

   Production Practice (1939) 111

2. Marking on Tool Joints for Identification of Drill String Components 113

3. Recommended Practice for Mill Slot and Groove Method of Drill

   String Identification 114

4. Identification of Lengths Covered by Inspection Standards 116

5. Drill Pipe and Tool Joint Color Code Identification . . . . . . . . . . . . . . . . . . . . . . 122 09

6. Tong Space and Bench Mark Position 123

7. Drill Collar Elevator 124

8. Drill Collar Grooves for Elevators and Slips 125

9. Drill Collar Wear 125

10. Modified Pin Stress-Relief Groove 126

1. Eccentric Hollow Section of Drill Pipe 133

2. Rotary Shouldered Connection 135

A-3a Make-up Torque Then Tension 137

A-3b Tension Then Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 03

A-3c Make-up Torque Then Tension 139

A-3d Tension Then Torque 139

1. Rotary Shouldered Connection Location of Dimensions for Bending

   Strength Ratio Calculations 141

2. Buckling Force vs Hole Curvature 143

3. Buckling Force vs Hole Curvature 144

4. Buckling Force vs Hole Curvature 145

Tables

1 New Drill Pipe Dimensional Data 4

2 New Drill Pipe Torsional and Tensile Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 03

1. New Drill Pipe Collapse and Internal Pressure Data 6

2. Used Drill Pipe Torsional and Tensile Data API Premium Class 7

3. Used Drill Pipe Collapse and Internal Pressure Data API Premium Class 8

4. Used Drill Pipe Torsional and Tensile Data API Class 2 9

5. Used Drill Pipe Collapse and Internal Pressure Data API Class 2 10

6. Mechanical Properties of New Tool Joints and New Grade E75 Drill Pipe 11

7. Mechanical Properties of New Tool Joints and New High Strength Drill Pipe . . 13

8. Recommended Minimum OD and Make-up Torque of Weld-on Type Tool 03

   Joints Based on Torsional Strength of Box and Drill Pipe 15

9. Buoyancy Factors 18

10. Rotary Shouldered Connection Interchange List 19

11. Drill Collar Weight (Steel) (pounds per foot) 34

12. Recommended Make-up Torque1 for Rotary Shouldered Drill Collar

    Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 03

13. Strength of Kellys 47

14. Contact Angle Between Kelly and Bushing for Development of Maximum

    Width Wear Pattern 48

15. Strength of Remachined Kellys 49

16. Section Modulus Values 53

17. Effect of Drilling Fluid Type on Coefficient of Friction 67

18. Hole Curvatures that Prevent Buckling 79

19. Youngstown Steel Test Results 96

20. Fatigue Endurance Limits Compressively Loaded Drill Pipe 98

21. Values Used in Preparing Figure 77 98

22. Classification of Used Drill Pipe 115

23. Classification of Used Tubing Work Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117 09

24. Hook-Load at Minimum Yield Strength for New, Premium Class (Used), and

    Class 2 (Used) Drill Pipe. 118

25. Hook-Load at Minimum Yield Strength for New, Premium Class (Used), and

Class 2 (Used) Tubing Work Strings 120

viii

Recommended Practice for Drill Stem Design and Operating Limits

1. Scope

   1. COVERAGE

      This recommended practice involves not only the selection of drill string members, but also the consideration of hole angle control, drilling ?uids, weight and rotary speed, and other operational procedures.

      
      

   2. SECTION COVERAGE

Sections 4, 5, 6, and 7 provide procedures for use in the

selection of drill string members. Sections 8, 9, 10, 11, 12,

98 and 15 are related to operating limitations which may reduce

the normal capability of the drill string. Section 13 contains a classi?cation system for used drill pipe and used tubing work strings, and identi?cation and inspection procedures for other drill string members. Section 14 contains statements regard- ing welding on down hole tools. Section 16 contains a classi-

?cation system for rock bits.

2 References

(See also Appendix B.) API

98 RP 5C1 Care and Use of Casing and Tubing

Bull 5C3 Bulletin on Formulas and Calculations for Casing, Tubing, Drill Pipe, and Line Pipe Properties

Spec 7 Specification for Rotary Drill Stem Ele- ments

RP 7A1 Recommended Practice for Testing of

98 Thread Compounds for Rotary Shouldered Connections

RP 13B-1 Recommended Practice Standard Proce- dure for Field Testing Water-Based Drill- ing Fluids

RP 13B-2 Recommended Practice Standard Proce- dure for Field Testing Oil-Based Drilling Fluids

ASTM1

D3370 Standard Practices for Sampling Water

98

NACE2

MR-01-75 Sulfide Stress Cracking Resistant Metallic Material for Oil Field Equipment

1American Society for Testing Materials, 100 Barr Harbor Drive, West Con- shocken, Pennsylvania 19428.

2NACE International, P.O. Box 218340, Houston, Texas 77218-8340.

1

1. Definitions

   1. bending strength ratio: The ratio of the section modulus of a rotary shouldered box at the point in the box where the pin ends when made up divided by the section mod- ulus of the rotary shouldered pin at the last engaged thread.

   2. bevel diameter: The outer diameter of the contact face of the rotary shouldered connection.

   3. bit sub: A sub, usually with 2 box connections, that is

      98

      used to connect the bit to the drill string.

   4. box connection: A threaded connection on Oil Country Tubular Goods (OCTG) that has internal (female) threads.

   5. calibration system: A documented system of gauge calibration and control. 98

   6. Class 2: An API service classi?cation for used drill pipe and tubing work strings.

   7. cold working: Plastic deformation of metal at a tem- perature low enough to insure or cause permanent strain. 98

   8. corrosion: The alteration and degradation of material by its environment.

   9. critical rotary speed: A rotary speed at which har- monic vibrations occur. These vibrations may cause fatigue failures, excessive wear, or bending.

   10. decarburization: The loss of carbon from the sur-

       face of a ferrous alloy as a result of heating in a medium that 98

       reacts with the carbon at the surface.

   11. dedendum: The distance between the pitch line and root of thread.

   12. dogleg: A term applied to a sharp change of direc- tion in a wellbore or ditch. Applied also to the permanent bending of wire rope or pipe.

   13. dogleg severity: A measure of the amount of change in the inclination and/or direction of a borehole, usu- ally expressed in degrees per 100 feet of course length.

   14. drift: A drift is a gauge used to check minimum ID of loops, ?owlines, nipples, tubing, casing, drill pipe, and drill collars.

   15. drill collar: Thick-walled pipe or tube designed to provide stiffness and concentration of weight at the bit.

   16. drill pipe: A length of tube, usually steel, to which special threaded connections called tool joints are attached.