Metal Ball Valves—Flanged, Threaded, and Welding Ends

API STANDARD 608

FIFTH EDITION, NOVEMBER 2012

Metal Ball Valves—Flanged, Threaded, and Welding Ends

Downstream Segment

API STANDARD 608

FIFTH EDITION, NOVEMBER 2012

Special Notes

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Copyright © 2012 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.

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms and Definitions 2

4. Pressure-Temperature Ratings 3

   1. Valve Rating 3

   2. Shell Rating 3

   3. Seat and Seal Rating 3

5. Design 4

   1. General 4

   2. Flow Passageway 4

   3. Body 5

   4. Antistatic Design (Electrical Continuity Between Ball-Stem-Body) 6

   5. Ball-Stem Design and Construction 6

   6. Ball Construction 6

   7. Packing Glands and Gland Bolting 6

   8. Operation 7

   9. End Flange Face Interruptions 7

   10. Valve Shell Joints 8

6. Materials 8

   1. Shell 8

   2. Trim 9

   3. Bolting 9

   4. Stem Seals, Body Seals, and Gaskets 9

   5. Identification Plate(s) 9

   6. Threaded Plugs 9

7. Inspection, Examination, and Testing 9

   1. Inspection and Examination 9

   2. Assembly 9

   3. Pressure Testing 9

   4. Fire Testing 10

8. Marking 10

9. Packaging and Shipping Requirements 10

10. Spare Parts 12

Annex A (informative) Information to Be Specified by the Purchaser 13

Annex B (informative) Figures 14

Figures

1. Flange Face Interruption Limits 8

2. Typical Fire-resistant Seats 11

3. Typical Unidirectional Valve Identification Plate Symbol 12

1. Typical Floating Ball Valve Components (One-piece Body/Unibody Illustrated)—Nomenclature 14

2. Typical Trunnion-mounted Ball Valve Components (Split-body Valve Illustrated)—Nomenclature 15

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Contents

Tables

Page

1. Minimum Seat Pressure-Temperature Rating—bar 3

2. Minimum Seat Pressure-Temperature Rating—psig 4

3. Cylinder Diameter for Categorizing Bore Size 4

Introduction

The purpose of this API standard is to establish additional design, operational, and performance requirements required by petroleum refining, petrochemical processing, and chemical processing end users that are in addition to and beyond the requirements established by ASME B16.34, Valves—Flanged, Threaded, and Welding End.

API 608 is intended to provide the similar additional requirements for steel and alloy steel ball valves beyond ASME B16.34 as do the following API standards for other valve types:

• API Standard 594, Check Valves: Flanged, Lug, Wafer and Butt-welding;

  
  

• API Standard 599, Metal Plug Valves—Flanged, Threaded, and Welding Ends;

  
  

• API Standard 600, Steel Gate Valves: Flanged and Butt-Welding Ends, Bolted Bonnets;

  
  

• API Standard 602, Steel Gate, Globe, and Check Valves for Sizes DN 100 and Smaller for the Petroleum and Natural Gas Industries;

  
  

• API Standard 603, Corrosion-resistant, Bolted Bonnet Gate Valves—Flanged and Butt-welding Ends;

  
  

• API Standard 609, Butterfly Valves: Double-flanged, Lug- and Wafer-type.

  
  

  vi

  
  

  Metal Ball Valves—Flanged, Threaded, and Welding Ends

  
  

  1. Scope

     
     

     1. This standard specifies the requirements for metal ball valves suitable for petroleum, petrochemical, and industrial applications that have:

        
        

• flanged ends in sizes DN 15 through DN 600 (NPS 1/2 through NPS 24);

  
  

• butt-welding ends in sizes DN 15 through DN 600 (NPS 1/2 through NPS 24);

  
  

• socket-welding ends in sizes DN 8 through DN 50 (NPS 1/4 through NPS 2);

  
  

• threaded ends in sizes DN 8 through DN 50 (NPS 1/4 through NPS 2). Corresponding to the nominal pipe sizes in ASME B36.10M.

  1. This standard applies to metal ball valves with pressure classes as follows:

     
     

• flanged ends in Classes 150, 300, and 600;

  
  

• butt-welding ends in Classes 150, 300, and 600;

  
  

• socket-welding ends in Classes 150, 300, 600, and 800;

  
  

• threaded ends in Classes 150, 300, 600, and 800.

  
  

  1. This standard establishes requirements for bore sizes described as:

     
     

• full bore;

  
  

• single reduced bore;

  
  

• double reduced bore.

1. This standard applies to floating (seat-supported) ball (Figure B.1) and trunnion ball valve designs (Figure B.2). These figures are to be used only for the purpose of establishing standard nomenclature for valve components— other floating and trunnion designs also exist.

   
   

2. This standard establishes additional requirements for ball valves that are otherwise in full conformance to the requirements of ASME B16.34, Standard Class.

   
   

1. 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 Standard 598, Valve Inspection and Testing

API Standard 607, Fire Test for Quarter-turn Valves and Valves Equipped with Non-metallic Seats

ASME B1.1 1, Unified Inch Screw Threads (UN and UNR Thread Form)

1