Centrifugal Fans for Petroleum, Chemical, and Gas Industry Services

API STANDARD 673

THIRD EDITION, DECEMBER 2014

Special Notes

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Copyright © 2014 American Petroleum Institute

Foreword

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iii

Contents

Page

1. Scope 1

2. Normative References 1

3. Terms and Definitions 6

4. General 11

   1. Unit Responsibility 11

   2. Unit Conversion 11

   3. Nomenclature 12

5. Requirements 12

   1. Dimensions 12

   2. Statutory Requirements 12

   3. Alternative Designs 12

   4. Conflicting Requirements 12

6. Design 12

   1. General 12

   2. Fan Housing 20

   3. Fan Housing Connections 21

   4. External Forces and Moments 23

   5. Rotating Elements 23

   6. Shaft Sealing of Fans 24

   7. Dynamics 25

   8. Bearings and Bearing Housings 31

   9. Lubrication 38

   10. Materials 40

   11. Nameplates and Rotation Arrows 43

7. Accessories 44

   1. Drivers 44

   2. Couplings 45

   3. Belt Drives 47

   4. Mounting Plates 47

   5. Controls and Instrumentation 53

   6. Piping 56

   7. Inlet Trash Screens 60

   8. Silencers 60

   9. Insulation and Jacketing 60

   10. Turning Gears 60

   11. Special Tools 60

8. Inspection, Testing, and Preparation for Shipment 61

   1. General 61

   2. Inspection 61

   3. Testing 63

   4. Preparation for Shipment 65

9. Vendor Data 67

   1. General 67

   2. Proposals 68

   3. Contract Data 70

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Contents

Page

Annex A (informative) Centrifugal Fan Datasheets 72

Annex B (informative) Terminology for Centrifugal Fans 80

Annex C (informative) Drive Arrangements 81

Annex D (normative) Lateral Critical Speed Analysis for Fans 84

Annex E (normative) Procedure for Determination of Residual Unbalance 89

Annex F (normative) Lubrication System Schematic for General Purpose Fans 97

Annex G (informative) Centrifugal Fans Vendor Drawing and Data Requirements 101

Figures

1. Fan Performance Terms 8

2. Fan Pressure Rise Terms 18

3. Fan Characteristic Curves 19

4. Rotor Response Plot 26

5. Threaded Connection for Vibration Transducer 39

6. Typical Mounting Plate Arrangement 1 49

7. Typical Mounting Plate Arrangement 2 50

8. Typical Mounting Plate Arrangement 3 51

9. Typical Mounting Plate Arrangement 4 52

1. Rotor Response Plot 84

2. Typical Mode Shapes 86

3. Calculated Rotor Response Plot for Unbalanced Response Analysis 88

1. (Blank) Residual Unbalance Worksheet 91

2. (Blank) Residual Unbalance Polar Plot Worksheet 92

3. Sample Residual Unbalance Worksheet for Left Plane 93

4. Sample Residual Unbalance Polar Plot Worksheet for Left Plane 94

5. Sample Residual Unbalance Worksheet for Right Plane 95

6. Sample Residual Unbalance Polar Plot Worksheet for Right Plane 96

F.1 Lube Oil System Schematic 98

Tables

1. Driver Trip Speeds 13

2. Common Hazardous Area Electrical Codes 14

3. Vibration Limits for Fans 29

4. Bearing Selection 31

5. Element Bearing Limiting Ndm/1000 32

6. Power Ratings for Motor Drives 45

7. Control Panel Plate Thickness 56

8. Minimum Requirements for Piping System Components 58

1. Lube Oil System Schematic 99

   
   

   vi

   
   

   Introduction

   
   

   Users of this standard should be aware that further or different requirements may be needed for individual applications. This 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 standard and provide details.

   
   

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

   
   

   
   

   vii

   
   

   Centrifugal Fans for Petroleum, Chemical, and Gas Industry Services

   
   

   1. Scope

      1. This standard covers the minimum requirements for centrifugal fans for use in petroleum, chemical, and gas industry services. Fan static pressure rise is limited to differential usually not exceeding 130 in. (330 cm) of water equivalent air pressure from a single impeller or each impeller in a two stage fan. This standard does not apply to axial flow, aerial cooler, cooling tower, and ventilation fans and positive displacement blowers.

         
         

         • 1.2 This standard covers equipment for both general purpose and special purpose applications. The purchaser shall determine which classification applies.

         
         

         NOTE Refer to Section 3 for definition of the terms general purpose and special purpose.

         
         

         1.3 Additional or overriding requirements applicable to special purpose applications are included at the end of each section (e.g. 6.7.5, etc.).

         
         

   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 vendor.

API Specification 5L, Specification for Line Pipe, Forty-Fifth Edition

API Recommended Practice 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Second Edition

API Standard 541, Form-wound Squirrel-cage Induction Motors—500 Horsepower and Larger, Fourth Edition API Standard 546, Brushless Synchronous Machines—500 kVA and Larger, Third Edition

API Standard 547, General-purpose Form-wound Squirrel Cage Induction Motors 250 Horsepower and Larger, First Edition

API Recommended Practice 578, Material Verification Program for New and Existing Alloy Piping Systems, Second Edition

API Standard 611, General-purpose Steam Turbines for Petroleum, Chemical, and Gas Industry Services, Fifth Edition

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

API Standard 613, Special Purpose Gear Units for Petroleum, Chemical, and Gas Industry Services, Fifth Edition

API Standard 614, Lubrication, Shaft-sealing, and Control-oil Systems and Auxiliaries for Petroleum, Chemical and Gas Industry Services, Fifth Edition

API Standard 670, Machinery Protection Systems, Fourth Edition

API Standard 671, Special-purpose Couplings for Petroleum, Chemical, and Gas Industry Services, Fourth Edition API Standard 677, General-purpose Gear Units for Petroleum, Chemical and Gas Industry Services, Third Edition

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