Shell-and-Tube Heat Exchangers

API STANDARD 660

NINTH EDITION, MARCH 2015 ADDENDUM 1, AUGUST 2020

Special Notes

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Copyright © 2015 American Petroleum Institute

Foreword

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms and Definitions 1

4. General 3

5. Proposal Information Required 4

6. Drawings and Other Required Data 5

   1. Outline Drawings and Other Supporting Data 5

   2. Information Required After Outline Drawings Are Reviewed 6

   3. Reports and Records 7

7. Design 8

   1. Design Temperature 8

   2. Cladding for Corrosion Allowance 8

   3. Shell Supports 9

   4. Stationary and Floating Heads 9

   5. Tube Bundle 10

   6. Nozzles and Other Connections 15

   7. Flanged External Girth Joints 16

   8. Girth Flange Joint Supplementary Design Requirements 20

   9. Expansion Joints 22

   10. Gaskets 22

   11. Handling Devices 24

   12. Requirements for Hydrogen Service 24

8. Materials 24

   1. General 24

   2. Requirements for Carbon Steel in Sour or Wet Hydrogen Sulfide Service 25

   3. Gaskets 25

   4. Tubes 25

9. Fabrication 25

   1. Shells 25

   2. Pass-partition Plates 26

   3. Connection Junctions 26

   4. Tubes 26

   5. Welding 26

   6. Heat Treatment 27

   7. Dimensional Tolerances 28

   8. Gasket Contact Surfaces Other Than Nozzle Flange Facings 28

   9. Tube Holes 30

   10. Tube-to-Tubesheet Joints 30

   11. Assembly 31

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       Contents

       Page

10. Inspection and Testing 31

    1. Quality Control 31

    2. Pressure Testing 34

    3. Nameplates and Stampings 34

11. Preparation for Shipment 35

    1. Protection 35

    2. Identification 36

12. Supplemental Requirements 36

    1. General 36

    2. Design 36

    3. Examination 36

13. Supplemental Requirements for Services Subject to High Temperature Hydrogen Service (HTHS) . . . 37 13.1 General 37

1. Design Temperature 37

2. Materials 38

3. Connections for Temperature Indication 38

4. Fabrication 38

5. Inspection and Testing 38

Annex A (informative) Recommended Practices 40

Annex B (informative) Shell-and-Tube Heat Exchanger Checklist 51

Annex C (informative) Shell-and-Tube Heat Exchanger Datasheets 54

Bibliography 67

Figures

1. Minimum Thickness of Tubes 10

2. Clearance Between Tube Holes and Transverse Baffle Edge with Longitudinal Baffle 12

3. Typical Cross-sections of Tube Bundle Showing Locations of Bypass Sealing Devices 14

4. Directions of Moments and Forces on Nozzles 16

Tables

1. Typical Designs for Floating-head Covers 11

2. Nozzle Allowable Forces and Moments at the Nozzle Neck to Shell/Channel Interface 17

3. Assembly Gasket Stress 21

4. Gasket Contact Surface Finishes 29

5. Flatness Tolerance on Peripheral Gasket Contact Surfaces 29

6. Maximum Allowable Tube Wall Thickness Reduction for Roller-expanded Tube-to-Tubesheet Joints . 30 7 Hardness Limits 32

B.1 Checklist for Shell-and-Tube Heat Exchangers 51

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Introduction

It is necessary that users of this standard be aware that further or differing requirements can 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 can be particularly applicable 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 section indicates a requirement for the purchaser to make a decision or provide information (for information, a checklist is provided in Annex B).

In this standard, where practical, U.S. Customary (USC) or other units are included in parentheses for information.

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Shell-and-Tube Heat Exchangers

1. Scope

   
   

   This standard specifies requirements and gives recommendations for the mechanical design, material selection, fabrication, inspection, testing, and preparation for shipment of shell-and-tube heat exchangers for the petroleum, petrochemical, and natural gas industries.

   
   

   This standard is applicable to the following types of shell-and-tube heat exchangers: heaters, condensers, coolers, and reboilers.

   
   

   This standard is not applicable to vacuum-operated steam surface condensers and feed-water heaters.

   
   

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.

   
   

   API RP 941, Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants

   ASME B16.5 1, Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard

   ASME PCC-1-2013, Guidelines for Pressure Boundary Bolted Flange Joint Assembly

   EJMA 2, Standards of the Expansion Joint Manufacturers Association

   NACE MR0103 3, Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments

   NACE MR0175, Petroleum and natural gas industries—Materials for use in H2S containing environments in oil and gas production—Parts 1, 2 and 3

   
   

   NACE SP0472, Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments

   TEMA 4, Ninth Edition, Standards of the Tubular Exchanger Manufacturers Association

   
   

3. Terms and Definitions

For the purposes of this document, the following definitions apply.

3.1

annular distributor

An additional chamber incorporated into a shell side nozzle to evenly distribute shell side fluids entering or exiting the tube bundle.

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

2. Expansion Joint Manufacturers Association, 25 North Broadway, Tarrytown, New York 10591, www.ejma.org.

3. NACE International (formerly the National Association of Corrosion Engineers), 1440 South Creek Drive, Houston, Texas 77084-4906, www.nace.org.

4. Tubular Exchanger Manufacturers Association, 25 North Broadway, Tarrytown, New York 10591, www.tema.org.

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