Check Valves: Flanged, Lug, Wafer, and Butt-welding

API STANDARD 594

EIGHTH EDITION, JULY 2017 EFFECTIVE DATE: JANUARY 14, 2018

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iii

Contents

Page

1. Scope 1

2. Normative References 2

3. Terms, Definitions, Acronyms, and Abbreviations 2

4. Pressure-temperature Ratings 3

   1. Valve Rating 3

   2. Temperature Restrictions 3

5. Design 4

   1. Body and Cover 4

   2. Plates and Disc 9

   3. Seating Surfaces 9

   4. External Bolts and Threaded Holes 9

   5. Flow Indication 9

   6. Gasket Surface 10

6. Material 10

   1. Body and Cover 10

   2. Plate and Disc 10

   3. Cover Gasket (Type “B” Valves) 11

   4. Trim 11

   5. Internal Wetted Parts 12

   6. Body Seat Rings 12

   7. Springs 12

   8. Pipe Plugs and Pin Retainers 13

   9. Nameplate 13

7. Inspection, Examination, Testing, and Repair 13

   1. Inspection and Examination 13

   2. Pressure Tests 13

   3. Repair of Defects 13

8. Marking 13

9. Shipment 14

   1. Coatings 14

   2. Valve Openings 14

   3. Packaging 14

10. Recommended Spare Parts 14

Annex A—API Monogram Program 15

Annex B—Information to be Specified by the Purchaser 19

Annex C—Standard Nomenclature for Valve Parts 21

Bibliography 26

Figures

1 Limitations for Flange Face Interruptions That Fall Within the Gasket Seating Area 10

1. Typical Type “A” Single-plate Wafer Check Valve 21

2. Typical Type “A” Dual-plate Wafer Check Valve 22

3. Typical Type “A” Dual-plate Lug Check Valve 23

   v

   Contents

   Page

4. Typical Type “A” Dual-plate Double-flanged Check Valve 24

5. Typical Type “B” Flanged Swing Check Valve 25

Tables

1. Minimum Body-wall Thickness by Class Designation 5

2. Type “A” Valve Face-to-Face Dimensions by Class Designation 6

3. Face-to-Face Dimensions by Class Designation for Double-flanged Valves 7

4. Seating-surface and Hinge Pin Nominal Trim Material 12

vi

Check Valves: Flanged, Lug, Wafer, and Butt-welding

1 Scope

If a product is supplied bearing the API Monogram and manufactured at a facility licensed by API, the requirements of Annex A apply.

This standard covers the design, material, face-to-face dimensions, pressure-temperature ratings, and examination, inspection, and test requirements for two types of check valves.

• Type “A” check valves are short face-to-face as defined in Table 2 and can be: wafer, lug, or double flanged; double flange as defined in Table 3; single plate or dual plate; gray iron, ductile iron, steel, nickel alloy, or other alloy designed for installation between Classes 125 and 250 gray iron flanges as specified in ASME B16.1, between Classes 150 and 300 ductile iron flanges as specified in ASME B16.42, between Classes 150 and 2500 flanges as specified in ASME B16.5, and between Classes 150 and 900 pipeline flanges as specified in MSS SP-44 or flanges as specified in ASME B16.47 Series A.

  
  

• Type “B” bolted cover swing check valves are long face-to-face as defined in 5.1.2 and can be: flanged or butt-welding ends of steel, nickel alloy, or other alloy material. End flanges shall be as specified in ASME B16.5, or ends shall be butt-welding as specified in ASME B16.25.

  
  

  This standard covers the following ranges:

  
  

• Type “A” valves:

  
  

  Classes 125 and 250, 50 ≤ DN ≤ 1200 (2 ≤ NPS ≤ 48) (excluding DN 90 [NPS 31/2]);

  
  

  a) Classes 150 and 300, 50 ≥ DN ≤ 1200 (2 ≤ NPS ≤ 48)*;

  
  

  b) Class 600, 50 ≤ DN ≤ 1050 (2 ≤ NPS ≤ 42)*;

  
  

  c) Classes 900 and 1500, 50 ≤ DN ≤ 600 (2 ≤ NPS ≤ 24)*;

  
  

  d) Class 2500, 50 ≤ DN ≤ 300 (2 ≤ NPS ≤ 12)*;

  
  

• Type “B” valves:

  
  

  a) Classes 150 through 1500, 50 ≤ DN ≤ 600 (2 ≤ NPS ≤ 24)*;

  
  

  b) Class 2500, 50 ≤ DN ≤ 300 (2 ≤ NPS ≤ 12)*.

  
  

  NOTE *Valve sizes DN 90 and DN 125 (NPS 31/2 and 5) are non-preferred sizes whose usage is discouraged.

  
  

• Sizes:

DN: 50, 65, 80, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 750, 900, 1050, 1200;

corresponding to nominal pipe sizes (NPS):

NPS: 2, 21/2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 24, 30, 36, 42, 48.

Information to be specified by the purchaser is shown in Annex B.