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

API STANDARD 594

SEVENTH EDITION, SEPTEMBER 2010

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

Downstream Segment

API STANDARD 594

SEVENTH EDITION, SEPTEMBER 2010

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iii

1. Scope 1

2. Normative References 2

3. Terms and Definitions 3

4. Pressure-temperature Ratings 4

   1. Valve Rating 4

   2. Temperature Restrictions 4

5. Design 4

   1. Body and Cover 4

   2. Plates and Disc 9

   3. Seating Surfaces 9

   4. External Bolts and Threaded Holes 10

   5. Flow Indication 10

   6. Gasket Surface. 10

6. Material 10

   1. Body and Cover 10

   2. Plate and Disc 10

   3. Cover Gasket (Type ‘B’ Valves) 10

   4. Trim 12

   5. Internal Wetted Parts 12

   6. Body Seat Rings 12

   7. Springs 13

   8. Pipe Plugs (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 (informative) Information to be Specified by the Purchaser 15

Annex B (informative) Standard Nomenclature for Valve Parts 17

Figures

1 Limitations for Flange Face Interruptions That Fall Within the Gasket Seating Area 11

1. Typical Type ‘A’ Single-plate Wafer Check Valve 17

2. Typical Type ‘A’ Dual-plate Wafer Check Valve 18

3. Typical Type ‘A’ Dual-plate Lug Check Valve 19

4. Typical Type ‘A’ Dual-plate Double-flanged Check Valve 20

5. Typical Type ‘B’ Flanged Swing Check Valve 21

Tables

1. Minimum Body-wall Thickness by Class 5

2. Minimum Body-wall Thickness by Class 6

3. Type ‘A’ Valve Face-to-Face Dimensions by Class 6

4. Type ‘A’ Valve Face-to-Face Dimensions by Class 7

5. Seating-surface Nominal Trim Material 12

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

1 Scope

This international standard covers 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 3 and Table 4 and can be: wafer, lug, or double flanged; single plate or dual plate; gray iron, ductile iron, steel, nickel alloy, or other alloy designed for installation between Classes 125 and 250 cast 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 steel flanges as specified in ASME B16.5, and between Classes 150 and 600 steel pipeline flanges as specified in MSS SP-44 or steel flanges as specified in ASME B16.47.

  
  

• 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:

  
  

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

  
  

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

  
  

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

  
  

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

  
  

  e) 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:

NPS: 2, 2 1/2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 24, 30, 36, 42, 48;

corresponding to nominal pipe sizes DN:

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

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

The standard nomenclature for valve parts is shown in Annex B. Figure B.1, Figure B.2, Figure B.3, and Figure B.4 illustrate typical Type ‘A’ check valves and Figure B.5 illustrates a typical Type ‘B’ check valve. These figures show typical designs only and are not to be construed as precluding other available designs that comply with the

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