Technical information / Test / API 598
Valve test standard
API 598
Valve inspection and testing: allowable leakage
Factory tests for American-standard valves (ASME Class): shell, closure and allowable leakage. Metal-seated valves are allowed limited leakage depending on size.
| NPS | DN | Liquiddrops/min | Gasbubbles/min | Check valve liquidml/min | Check valve gasm³/h | Durationshell · closure s |
|---|---|---|---|---|---|---|
| 1/2" | DN15 | 0 | 0 | 1.5 | 0.021 | 15 · 15 |
| 3/4" | DN20 | 0 | 0 | 2.3 | 0.032 | 15 · 15 |
| 1" | DN25 | 0 | 0 | 3 | 0.042 | 15 · 15 |
| 1 1/4" | DN32 | 0 | 0 | 3.8 | 0.053 | 15 · 15 |
| 1 1/2" | DN40 | 0 | 0 | 4.5 | 0.063 | 15 · 15 |
| 2" | DN50 | 0 | 0 | 6 | 0.084 | 15 · 15 |
| 2 1/2" | DN65 | 5 | 10 | 7.5 | 0.105 | 60 · 60 |
| 3" | DN80 | 6 | 12 | 9 | 0.126 | 60 · 60 |
| 4" | DN100 | 8 | 16 | 12 | 0.168 | 60 · 60 |
| 5" | DN125 | 10 | 20 | 15 | 0.21 | 60 · 60 |
| 6" | DN150 | 12 | 24 | 18 | 0.252 | 60 · 60 |
| 8" | DN200 | 16 | 32 | 24 | 0.336 | 120 · 120 |
| 10" | DN250 | 20 | 40 | 30 | 0.42 | 120 · 120 |
| 12" | DN300 | 24 | 48 | 36 | 0.504 | 120 · 120 |
| 14" | DN350 | 28 | 56 | 42 | 0.588 | 300 · 120 |
| 16" | DN400 | 32 | 64 | 48 | 0.672 | 300 · 120 |
| 18" | DN450 | 36 | 72 | 54 | 0.756 | 300 · 120 |
| 20" | DN500 | 40 | 80 | 60 | 0.84 | 300 · 120 |
| 24" | DN600 | 48 | 96 | 72 | 1.008 | 300 · 120 |
| 26" | DN650 | 52 | 104 | by agreement | by agreement | 300 · 120 |
| 28" | DN700 | 56 | 112 | by agreement | by agreement | 300 · 120 |
| 30" | DN750 | 60 | 120 | by agreement | by agreement | 300 · 120 |
| 32" | DN800 | 64 | 128 | by agreement | by agreement | 300 · 120 |
| 36" | DN900 | 72 | 144 | by agreement | by agreement | 300 · 120 |
| 40" | DN1000 | 80 | 160 | by agreement | by agreement | 300 · 120 |
| 42" | DN1050 | 84 | 168 | by agreement | by agreement | 300 · 120 |
| 48" | DN1200 | 96 | 192 | by agreement | by agreement | 300 · 120 |
Notes
- This table has been compiled by Emsal from the relevant standards. For the full text of the standard, refer to API.
- CWP is the valve's pressure rating at 38 °C (ASME B16.34, Group 1.1 carbon steel). The shell test is at 1.5 × CWP, the high-pressure closure test at 1.1 × CWP and the low-pressure gas test at 4–7 bar.
- No leakage is allowed for soft-seated valves. For metal-seated valves up to NPS 2: no visible leakage with liquid and less than 1 bubble during the test with gas; for larger sizes, 2 drops/min and 4 bubbles/min per NPS.
- Metal-seated check valves: 3 ml/min liquid or 0.042 m³/h gas per NPS. For check valves above NPS 24 the limit is agreed between purchaser and manufacturer. 1 ml = 16 drops.
- Older editions of API 598 gave leakage in size bands (NPS 2–6: 12 drops/min, 8–12: 20, 14 and above: 28). The values shown are from the current table, identical in two independent sources.
- The backseat test is performed only on valves with a backseat. Durations are minimums, counted from when the valve reaches full test pressure.
- Accuracy and currency are not guaranteed; use the current edition of the standard for design and purchasing decisions. How the library is compiled →
Related pages
| 1 | European test standard, leakage rates A–G EN 12266-1 → |
| 2 | Class pressure ratings Pressure classes → |
| 3 | Check valve face-to-face dimensions API 594 → |