Sealless Centrifugal Pumps for Petroleum, Petrochemical, and Gas Industry Process Service

API STANDARD 685

SECOND EDITION, FEBRUARY 2011

Sealless Centrifugal Pumps for Petroleum, Petrochemical, and Gas Industry Process Service

Downstream Segment

API STANDARD 685

SECOND EDITION, FEBRUARY 2011

Special Notes

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Copyright © 2011 American Petroleum Institute

Foreword

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Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standards@api.org.

iii

Introduction vi

1. Scope 1

2. Normative References 1

3. Definition of Terms 4

4. General 12

   1. Unit Responsibility 12

   2. Nomenclature 12

5. Requirements 12

   1. System of Measurements 12

   2. Statutory Requirements 13

   3. Requirements 13

6. Basic Design 13

   1. General 13

   2. Pressure Casings 19

   3. Nozzles and Pressure Casing Connections 21

   4. External Nozzles Forces And Moments 23

   5. Rotors 27

   6. Wear Rings and Running Clearances 27

   7. Secondary Control/Containment 28

   8. Dynamics 30

   9. Process Cooled/Lubricated Bearings and Bearing Housings 34

   10. Materials 35

   11. Nameplates and Rotation Arrows 40

7. Accessories 41

   1. Drivers 41

   2. Couplings and Guards 42

   3. Baseplates and Support Frames 42

   4. Controls and Instrumentation 42

   5. Piping and Appurtenances 43

   6. Special Tools 43

8. Inspection, Testing, and Preparation for Shipment 44

   1. General 44

   2. Inspection 45

   3. Testing 47

   4. Preparation for Shipment 53

9. Specific Pump Sections 54

   1. Magnetic Drive Pumps 54

   2. Canned Motor Pumps 66

10. Vendor’s Data 68

    1. General 68

    2. Proposals 69

    3. Contract Data 71

Annex A (informative) Application Information 74

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Annex B (informative) Hazard-Based Specification of Control/Containment Guidelines 80

Annex C (informative) Sealless Centrifugal Pump Nomenclature 84

Annex D (normative) Circulation and Cooling Water Piping Schematics 88

Annex E (informative) Instrumentation and Protective Systems 92

Annex F (normative) Criteria for Piping Design 95

Annex G (informative) Materials Class Selection Guidance 110

Annex H (normative) Materials and Material Specifications for Pump Parts 112

Annex I (informative) Magnet Materials for Magnetic Couplings 123

Annex J (normative) Determination of Residual Unbalance 125

Annex K (normative) Pressure Temperature Profiles in the Recirculation Circuit 131

Annex L (informative) Lateral Analysis 134

Annex M (normative) Standard Baseplates 140

Annex N (informative) Inspector’s Checklist 142

Annex O (informative) Vendor Drawing and Data Requirements 144

Annex P (informative) Test Data Summary 153

Annex Q (informative) Specific Speed and Suction-Specific Speed 157

Annex R (informative) Typical Datasheets 158

Figures

1. Typical Gusset Design 23

2. Machined Face Suitable for Gasket Containment if Using Cylindrical Threads 24

3. Coordinate System for the Forces and Moments in Table 4: Vertical Inline Pumps 26

4. Coordinate System for the Forces and Moments in Table 4: Horizontal Pumps 26

5. Relationship Between Flow and Vibration 31

6. Locations and Provisions for Taking Vibration Readings 32

7. Vibration Limits for Horizontal Pumps Running Above 3600 r/min or Absorbing More

   than 300 kW (400 hp) per Stage 33

8. Rotating Component Dimensions to Determine if Single-Plane Balancing is Allowable 34

9. Speed Torque Curve 57

B.1 Logic Diagram 81

1. Magnetic Drive Pump, Separately Coupled 85

2. Canned Motor Pump 86

3. Magnetic Drive Pump Terms Defined in Section 3 87

4. Canned Motor Pump Terms Defined in Section 3 87

1. Annex D Legend 88

2. Clean Circulating Fluid Arrangements 89

3. Dirty or Special Circulating Fluid Arrangements 90

4. Cooling Water Piping Arrangements 91

1. Magnetic Driven Pump 93

2. Canned Motor Pump 94

1. Residual Unbalance Worksheet 127

   
   

2. Residual Unbalance Worksheet — Polar Chart 128

3. Example of Completed Residual Unbalance Worksheet 129

4. Example of Completed Residual Unbalance Worksheet—Best-fit Circle for Residual Unbalance 130

1. Typical Pressure-Temperature Profile in Magnetic Drive Pump 132

2. Typical Pressure-Temperature Profile in Canned Motor Pump 133

1. Damping Factor versus Frequency Ratio 136

2. Typical Campbell Diagram 137

M.1 Standard Baseplate 141

O.1 Example Distribution Record 145

1. Test Data Summary Form 154

2. Example of Test Curve Format (SI units) 155

3. Example of Test Curve Format (USC units) 156

Tables

1. Water Cooling Systems–Conditions on the Water Side 17

2. Common Hazardous Area Electrical Codes 18

3. Casting Factors 19

4a Nozzle Loadings (SI Units) 24

4b Nozzle Loading (U.S. Customary Units) 25

1. Minimum Internal Running Clearances 29

2. Vibration Limits for Overhung Pumps 31

3. Welding Requirements 38

4. Power Ratings for Motor Drivers 41

5. Pressure Casing Material Inspection Requirements 46

6. Material Inspection Standards 47

7. Performance Acceptance Criteria 48

8. Magnetic Coupling Torque Service Factors 56

9. Stiffness Criteria 65

10. Recommended Spare Parts 70

1. H Statement Classification Table 82

2. R Phrase Classification Table 83

E.1 Instrumentation and Protective systems 92

1. Nozzle Sizes and Location Coordinates for Example 1A 99

2. Applied Nozzle Loadings for Example 1A 99

3. Proposed Applied Nozzle Loadings for Example 2A 102

4. Nozzle Sizes and Location Coordinates for Example 1B 103

5. Nozzle Sizes and Location Coordinates for Example 1B 104

6. Proposed Applied Nozzle Loadings for Example 2B 107

G.1 Material Classes for Sealless Centrifugal Pump Services 110

1. Material Classes for Pump Parts 113

2. Material Specifications for Pump Parts. 115

3. Non-metallic Wear Part Materials 122

I.1 Magnetic Materials Properties Overview and Temperature Limits 124

L.1 Rotor Lateral Analysis Logic Diagram 134

M.1 Dimensions of Standard Baseplates 140

N.1 Inspector’s Checklist 142

Introduction

Users of this National Standard should be aware that further or differing requirements may be needed for individual applications. This National Standard is not intended to inhibit a 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 Vendor should identify any variations from this National Standard and provide details.

Annex A contains application specific information and cautions.

Annex B contains hazard-based criteria for secondary containment/control specification. Annex C contains nomenclature for sealless pumps.

Annex D contains schematic drawings of cooling water and circulation systems. Annex E defines options for instrumentation and protective systems.

Annex F specifies criteria for piping design.

Annex G gives guidance on material class selection.

Annex H specifies requirements and gives guidance on materials selection. Annex I provides information on magnetic materials for magnetic couplings. Annex J specifies requirements for determining residual unbalance.

Annex K provides information and examples for pressure temperature profiles in the recirculation flowpath. Annex L specifies requirements for lateral analysis.

Annex M specifies requirements for standard baseplates. Annex N contains an inspector's checklist.

Annex O contains forms which may be used to indicate Vendor drawing and data requirements. Annex P contains forms which may be used to record test data.

Annex Q specifies calculations for specific speed and suction specific speed. Annex R contains a data sheet format which Purchasers are encouraged to use.

This National Standard requires the Purchaser to specify certain details and features.

A bullet () at the beginning of a subclause or paragraph indicates that either a decision by, or further information from, the Purchaser is required. Further information should be shown on the data sheets or stated in the quotation request and purchase order.

In this National Standard, US Customary units are included in brackets for information.

vi

Sealless Centrifugal Pumps for Petroleum, Petrochemical, and Gas Industry Process Service

1. Scope

   1. This standard specifies the minimum requirements for sealless centrifugal pumps for use in petroleum, heavy duty petrochemical and gas industry services. Refer to Annex A for application information. Notes following a clause are informative.

      
      

   2. This standard is applicable to single stage overhung pumps of two classifications, Magnetic Drive Pumps (MDP) and Canned Motor Pumps (CMP). Sections 2 through 8 and Section 10 cover requirements applicable to both classifications. Section 9 is divided into two subsections and covers requirements unique to each classification.

      
      

      NOTE Extension of applicability to other designs such as multistage will need additional input and agreement between Purchaser and Supplier.

      
      

   3. When application of sealless pumps is indicated, relevant industry operating experience suggests sealless pumps produced to this Standard may be used for many applications and should be applied when conditions exceed any of the following:

      
      

      — Discharge pressure	1900 kPa	(275 psig)
      — Suction pressure	500 kPa	(75 psig)
      — Pumping temperature	150 °C	(300 °F)
      — Rotative speed	3600 r/min
      — Rated total head	120 m	(400 ft)
      — Impeller diameter	330 mm	(13 in.)

      
      

      NOTE For sealed pumps, refer to ISO Standard 13709 (API 610).

      
      

2. Normative References

   1. The following referenced documents are indispensable for the application of this document. The way in which these referenced documents are cited determines the extent (in whole or in part) to which they apply. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

API 547, General-purpose Form-wound Squirrel-cage Induction Motors—250 Horsepower and Larger API 611, General-purpose Steam Turbines for Petroleum, Petrochemical, and Gas Industry Service API 670, Machinery Protection Systems

API 677, General-purpose Gear Units for Petroleum, Chemical, and Gas Industry Services

ABMA 7 1, Shaft and Housing Fits for Metric Radial Ball and Roller Bearings (Except Tapered Roller Bearings) Conforming to Basic Boundary Plan

1) American Bearing Manufacturers Association, 2025 M Street, NW, Suite 800, Washington, DC 20036, USA.

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