Machinery Protection Systems

API STANDARD 670

FIFTH EDITION, NOVEMBER 2014

Special Notes

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Copyright © 2014 American Petroleum Institute

Foreword

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Contents

Page

1. Scope 1

   1. General 1

   2. Alternative Designs 1

   3. Conflicting Requirements 1

2. Normative References 1

3. Terms, Definitions, Acronyms, and Abbreviations 3

   1. Terms and Definitions 3

   2. Acronyms and Abbreviations26

4. General Design Specifications 27

   1. Component Temperature Ranges 27

   2. Humidity 27

   3. Shock 28

   4. Chemical Resistance 28

   5. Accuracy 28

   6. Interchangeability 31

   7. Scope of Supply and Responsibility 31

   8. Segregation 31

   9. System Enclosures and Environmental Requirements 31

   10. Power Supplies 34

   11. Machinery Protection System Features/Functions 35

   12. System Output Relays 38

   13. Digital Communication Links 39

   14. System Wiring and Conduits 40

   15. Grounding of the Machinery Protection System 42

   16. System Security, Safeguards, Self-tests, and Diagnostics 43

   17. Reliability 44

5. Sensors and Transducers 44

   1. Radial Shaft Vibration, Axial Position, Phase Reference, Speed Sensing, Flow, and Piston Rod Drop Transducers44

   2. Seismic Transducers. 48

   3. Temperature Sensors 51

6. Sensor and Transducer Arrangements 52

   1. Locations and Orientation 52

   2. Mounting 60

   3. Identification of Sensor Systems 62

7. Vibration Monitor Systems 62

   1. General 62

   2. Power Supplies 64

   3. System Output Relays 64

   4. Monitor Systems 65

   5. Location of Monitor Systems 71

8. Electronic Overspeed Detection System 71

   1. General 71

   2. Accuracy 72

   3. Segregation 72

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   4. Functions 72

9. Surge Detection Systems 75

   1. General 75

   2. Accuracy 75

   3. Segregation 75

   4. Functions 77

10. Emergency Shutdown Systems (ESDs) 79

    1. General 79

    2. Functional Requirements 81

    3. ESD Security 82

    4. ESD Arrangement 82

    5. ESD Interface 83

    6. Display, Indications 86

    7. System Inputs 86

    8. System Outputs 88

11. Inspection, Testing, and Preparation for Shipment 88

    1. General 88

    2. Inspection 88

    3. Testing 88

    4. Preparation for Shipment 89

    5. Mechanical Running Test 89

    6. Field Testing 89

12. Vendor’s Data 93

    1. General 93

    2. Proposals 95

    3. Contract Data 96

Annex A (informative) Machinery Protection System Datasheets 98

Annex B (informative) Typical Responsibility Matrix Worksheet 107

Annex C (normative) Accelerometer Application Considerations 108

Annex D (normative) Signal Cable 113

Annex E (normative) Gearbox Casing Vibration Considerations 116

Annex F (normative) Field Testing and Documentation Requirements 118

Annex G (informative) Contract Drawing and Data Requirements 121

Annex H (informative) Typical System Arrangement Plans 126

Annex I (informative) Setpoint Multiplier Considerations 133

Annex J (normative) Electronic Overspeed Detection System Considerations 137

Annex K (informative) Surge Detection and Antisurge Control 141

Annex L (informative) Safety Integrity Level 145

Annex M (informative) Considerations Regarding Spurious Shutdowns and the Use of Functional Safety Methodology to Reduce Economic Losses 165

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Contents

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Annex N (informative) Condition Monitoring 169

Annex O (normative) Overspeed 219

Annex P (informative) Reciprocating Compressor Monitoring 226

Annex Q (informative) Considerations when Using Wireless Connectivity Technologies 236

Bibliography 244

Figures

1. Machinery Protection System 13

2. Standard Monitor System Nomenclature 14

3. Transducer System Nomenclature 23

4. Typical Curves Showing Accuracy of Proximity Transducer System 30

5. Typical Conduit Cable Arrangement 40

6. Typical Armored Cable Arrangement 41

7. Inverted Gooseneck Trap Conduit Arrangement 41

8. Typical Instrument Grounding 43

9. Standard Proximity Probe and Extension Cable 44

10. Standard Options for Proximity Probes 45

11. Standard Magnetic Speed Sensor with Removable (Nonintegral) Cable and Connector 47

12. Standard Axial Position Probe Arrangement 53

13. Typical Piston Rod Position Probe Arrangement 54

14. Typical Installations of Radial Bearing Temperature Sensors 58

15. Standard Installation of Radial Bearing Temperature Sensors 59

16. Typical Installation of Thrust Bearing Temperature Sensors 59

17. Piston Rod Drop Calculations 67

18. Piston Rod Position Measurement Using Phase Reference Transducer for Triggered Mode 68

19. Surge Detection and Antisurge Control Systems 76

20. Surge Detection with Compressor Inlet Temperature 78

21. Typical System Arrangement Using Distributed Architecture 84

22. Typical System Arrangement Using Integrated Architecture 85

23. Calibration of Radial Monitor and Setpoint for Alarm and Shutdown 90

24. Calibration of Axial Position (Thrust) Monitor 91

25. Typical Field Calibration Graph for Radial and Axial Position (Gap) 92

1. Typical Flush-mounted Accelerometer Details 109

2. Typical Nonflush-mounted Arrangement Details for Integral Stud Accelerometer 110

3. Typical Nonflush-mounted Arrangement for Integral Stud Accelerometer with Protection Housing. . 111

1. Typical System Arrangement for a Turbine with Hydrodynamic Bearings 127

2. Typical System Arrangement for Double-helical Gear 128

3. Typical System Arrangement for a Centrifugal Compressor or a Pump with Hydrodynamic

   Bearings 129

4. Typical System Arrangement for an Electric Motor with Sleeve Bearings 130

5. Typical System Arrangement for a Pump or Motor with Rolling Element Bearings 131

6. Typical System Arrangement for a Reciprocating Compressor 132

I.1 Setpoint Multiplication Example 134

1. Overspeed Protection System 137

2. Relevant Dimensions for Overspeed Sensor and Multitooth Speed Sensing Surface

   Application Considerations 138

3. Precision-machined Overspeed Sensing Surface 139

Contents

Page

1. Compressor Performance Limitations 142

2. Pressure and Flow Variations During a Typical Surge Cycle 142

1. Risk Graph as per VDMA 4315L 151

2. Risk Graph as per ISO 13849 154

3. Relationship Between Categories, DCavg, MTTFd of Each Channel, and PL 156

4. Functional Block Diagram of Typical Protection Loop with a Single Solenoid Valve 158

5. Functional Block Diagram of Typical Protection Loop with a Dual Solenoid Valve 158

M.1 Process Block Diagram 168

1. Orbit Plot and Order Spectrum 175

2. Case Plot with x-axis Configured for Frequency 176

3. Waterfall Plot with Half Spectrum and x-axis Configured for Frequency 176

4. Waterfall Plot with x-axis Configured for Frequency 177

5. Waterfall Plot with Full Spectrum and x-axis Configured for Orders 177

6. Example of Broken Fan Blade Causing Unbalance Condition. Diagram Shows the Heavy Spot.

   The Spectrum Indicates High 1X Peak and the Waveform Resembles a Sine Wave. 178

7. Offset Misalignment 178

8. Angular Misalignment 178

9. Offset Misalignment Spectrum Shows 1X with Larger 2X Peak. Offset Misalignment Waveform

   Shows Two Peaks per Revolution. 179

10. Looseness Can Be Caused by Excessive Clearance in a Bearing. The Looseness Spectrum

    Shows Many Harmonics of 1X. Looseness Waveform Shows Random Peaks—No Pattern. 179

11. Orbit and Time Waveform Plot of a Rub on a Motor 180

12. Full Spectrum Plot of a Rub on a Motor 180

13. Antifriction Bearings 181

14. Spectrum (left) Shows Cage Defect Frequency. The Waveform (right) Has a Clear Impacting

    Pattern 182

15. Spectrum (left) Plot of Outer Race Defect Generates Spiked Peaks at Harmonics of BPFO

    The Waveform (right) Shows a High Number of Impacts Closely Spaced Together 183

16. The Spectrum (top) Shows High Frequency Peaks Typically Surrounded by Sidebands

    The Waveform (bottom) Shows Repeating Peaks with a Modulated Amplitude. 184

17. The First Waveform (upper left) is of Early Stage Defect. The Second Waveform (upper right)

    is of an Advanced Stage Defect. The Third Plot (bottom) is the Trend of Waveform Amplitude. 185

18. Typical Multistage Gearbox 186

19. Spectrum Showing 1X and 2X of Gear Mesh Frequency 186

20. Early Stage Gear Wear Showing 1X, 2X, and 3X of Gear Mesh Frequency. 187

21. Late Stage Gear Wear Showing Sidebands Around Gear Mesh 187

22. Waveform Showing Amplitude Modulation of Impacts 188

23. Circle Plot of the Waveform Reveals the Number and Location of Broken Teeth 188

24. Fluid Wedge Illustration 189

25. Waterfall Representation of Whirl and Whip Phenomenon 190

26. Orbit and Time Waveform Representation of Whirl and Whip Phenomenon 191

27. Examples of Oil Whirl Frequency Spectrums. 192

28. Examples of Oil Whirl Orbit and Frequency Spectrum 192

29. Waterfall Plot with Orbits Displaying Oil Whirl and Oil Whip 193

30. Bode Plot showing Resonant Frequency 194

31. Cascade Plot of a Start-up. A Structural Resonance is Present in the Data as Well as the Normal 1X Vibration. When Machine Speed Becomes Equal to the Resonant Frequency, a Large Increase

    in Amplitude Occurs. 194

32. Frequency Spectrum of Cavitation Fault 196

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33. Time Waveform of Cavitation Fault 197

34. Probe Mount Frequency Ranges 207

35. Condition Monitoring Configurations with Wireless Connectivity 217

O.1 The Peak Kinetic Energy of the Rotor 219

1. Unidirectional Wireless Communication 240

2. Omnidirectional Wireless Communication 240

3. Star Topology Network 241

4. Mesh Topology Network 242

5. Cluster Tree Topology Network 243

Tables

1. Machinery Protection System Accuracy Requirements 29

2. Summary of Allowable Usage of Wireless Technology for Machinery Protection Systems 32

3. Minimum Separation Between Installed Signal and Power Cables 42

4. Accelerometer Test Points (SI) 93

5. Accelerometer Test Points (USC Units) 94

D.1 Color Coding for Single-circuit Thermocouple Signal Cable 115

1. Tools and Instruments Needed to Calibrate and Test Machinery Protection Systems 118

2. Data, Drawing, and Test Worksheet 119

1. Typical Milestone Timeline 121

2. Sample Distribution Record (Schedule) 122

1. Recommended Dimensions for Speed Sensing Surface when Magnetic Speed Sensors Are Used . . 140

2. Recommended Dimensions for Nonprecision Speed Sensing Surface when Proximity Probe

   Speed Sensors Are Used 140

3. Recommended Dimensions for Precision-machined Speed Sensing Surface when Proximity

Probe Speed Sensors Are Used 140

1. Safety Integrity Levels and Probability of Failure 149

2. Performance Level as per ISO 13849 and Safety Integrity Level as per IEC 61508/61511 151

3. Definition of the Range of the Parameter Severity, S 152

4. Definition of the Range of the Parameter Probability of Presence in the Hazardous Zone—F 153

5. Definition of Vulnerability V and Unavoidability A 154

6. Definition of the Range of the Parameter AV (Unavoidability Considering the Vulnerability) 154

7. Definition of the Range of the Parameter W (Probability of the Occurrence of the Unwanted Event) . 154 L.8 Table of Calculated PFDavg for Example of L.7.2.2 161

1. Mean Time to Dangerous Failure of Each Channel (MTTFd) 163

2. Diagnostic Coverage (DC) 163

3. Table of Calculated PFDavg for Example in L.8.4 164

1. MPS and CMS Objectives and Goals 170

2. MPS and CMS Content Comparison 171

3. Probe Mount Frequency Ranges 206

1. Typical Protective Signals 233

2. Typical Condition Signals 234

Machinery Protection Systems

1. Scope

   1. General

      
      

      This standard covers the minimum requirements for a machinery protection system (MPS) measuring radial shaft vibration, casing vibration, shaft axial position, shaft rotational speed, piston rod drop, phase reference, overspeed, surge detection, and critical machinery temperatures (such as bearing metal and motor windings). It covers requirements for hardware (transducer and monitor systems), installation, documentation, and testing.

      
      

      NOTE A bullet ( ●) at the beginning of a subsection or paragraph indicates that either a decision is required or further information is to be provided by the purchaser. This information should be indicated on the datasheets (see Annex A); otherwise, it should be stated in the quotation request or in the order.

      
      

   2. Alternative Designs

      
      

      The MPS vendor may offer alternative designs. Equivalent metric dimensions and fasteners may be substituted as mutually agreed upon by the purchaser and the vendor.

      
      

   3. Conflicting Requirements

      
      

      In case of conflict between this standard and the inquiry or order, the information included in the order shall govern.

      
      

2. Normative References

   1. The editions of the following standards, codes, and specifications that are in effect at the time of publication of this standard shall, to the extent specified herein, form a part of this standard. The applicability of changes in standards, codes, and specifications that occur after the inquiry shall be mutually agreed upon by the purchaser and the MPS vendor.

API Recommended Practice 552, Transmission Systems

API Standard 610, Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries

API Standard 611, General Purpose Steam Turbines for Petroleum, Chemical, and Gas Industry Systems

API Standard 612, Petroleum Petrochemical and Natural Gas Industries—Steam Turbines—Special-Purpose Applications

ANSI MC96.1 1, Temperature Measurement Thermocouples

ASME Y14.2M 2, Line Conventions and Lettering

EN 61000-6-2:2005 3, Electromagnetic Compatibility Generic Immunity Standard; Part 2: Industrial Environment ICEA S-61-402 4, Thermoplastic-Insulated Wire and Cable for the Transmission and Distribution of Electrical Energy IEC 60079 5, (all parts) Explosive atmospheres

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

2. ASME International, 3 Park Avenue, New York, New York 10016-5990, www.asme.org.

3. European Committee for Standardization, Rue de Stassart 36, B-1050 Brussels, Belgium, www.cenorm.be.

4. Insulated Cable Engineers Association, P.O. Box 1568, Carrollton, Georgia 30112, www.icea.net.

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