API 6D is primarily applicable to ball valves, gate valves, check valves, plug valves, and other valve types used in piping systems. Its product specifications cover nominal diameters (NPS) from 2 inches to 48 inches, and working pressure ratings from 150 psi to 2500 psi (Class 150~Class 2500), meeting diverse operating conditions. Valve materials include carbon steel, stainless steel, and alloy steel, adaptable to various media environments and temperature conditions.
Need an API 6D size fast? Here is a mobile-friendly, searchable dimension table for pipeline ball, gate, and check valves. Bookmark for your next RFQ.
API 6D Common Caliber Table
| Nominal Pipe Size (NPS / Inch) | Metric Equivalent (DN / mm) | Common pressure levels(Class) |
| 2" | 50 | 150, 300, 600, 900, 1500, 2500 |
| 3" | 80 | 150, 300, 600, 900, 1500, 2500 |
| 4" | 100 | 150, 300, 600, 900, 1500, 2500 |
| 6" | 150 | 150, 300, 600, 900, 1500, 2500 |
| 8" | 200 | 150, 300, 600, 900, 1500, 2500 |
| 10" | 250 | 150, 300, 600, 900, 1500, 2500 |
| 12" | 300 | 150, 300, 600, 900, 1500, 2500 |
| 14" | 350 | 150, 300, 600, 900, 1500 |
| 16" | 400 | 150, 300, 600, 900, 1500 |
| 20" | 500 | 150, 300, 600, 900, 1500 |
| 24" | 600 | 150, 300, 600, 900, 1500 |
| 30" | 750 | 150, 300, 400, 600, 900 |
| 36" | 900 | 150, 300, 400, 600, 900 |
| 42" - 60" | 1050 - 1500 | 150, 300, 400, 600 |
Go beyond simple sizing. Understand how API 6D dimensions impact pigging capability, DBB/DIB functions, and why testing durations differ from API 598.
API 6D vs. Other Valve Standards
| Feature | API 6D | API 600 / 603 | API 608 | ASME B16.34 |
| Main Application | Midstream Pipelines (Oil & Gas Transmission) | Refining & Petrochemical (Downstream) | Industrial & Chemical Process | General Industrial Applications |
| Valve Types | Ball, Gate, Check, and Plug Valves | Cast Steel / Stainless Steel Gate Valves | Metal Ball Valves | All Types (Flanged, BW, Threaded, etc.) |
| Core Focus | Sealing Integrity & Pigging Capability | Corrosion Allowance & Wall Thickness Tolerance | Operational Safety (Anti-blowout, etc.) | Pressure-Temperature (P-T) Ratings |
| Typical Functions | DBB / DIB / Self-Relieving | High-Temp & High-Pressure Sealing | Anti-static / Fire-safe Design | Structural Strength & Material Specs |
| Testing Standard | API 6D (Inherent testing requirements) | API 598 | API 598 | ASME B16.34 (or as specified) |
| Size Range | NPS 2 to NPS 60 | NPS 1 to NPS 100 | NPS 1/4 to NPS 24 | Full Range |
Confusion between pipeline and refinery standards can be costly. Our master comparison table breaks down the technical differences to help you specify the right valve for your project.
High pressure series face-to-face dimension table
| NPS (Inch) | Class 900 (RF) | Class 1500 (RF) | Class 2500 (RF) |
| 2" | 368 | 368 | 451 |
| 3" | 381 | 470 | 572 |
| 4" | 457 | 546 | 673 |
| 6" | 610 | 705 | 914 |
| 8" | 737 | 832 | 1022 |
| 10" | 838 | 991 | 1270 |
| 12" | 965 | 1130 | 1422 |
API6D standard Valve sealing grade and testing requirements
| Sealing Class | Allowed Leakage Rate | Test Medium | Application Scope |
|---|---|---|---|
| Class Ⅰ | 1×10⁻² ml/min/in | Gas (Air, Nitrogen) | Low-pressure Corrosion-resistant Valves |
| Class Ⅱ | 1×10⁻³ ml/min/in | Gas | Medium-low-pressure Industrial Valves |
| Class Ⅲ | 1×10⁻⁴ ml/min/in | Gas | High-demand Systems such as Natural Gas Transmission |
| Class Ⅳ | No Leakage Allowed | Water (Liquid) | Severe Service Conditions especially Safety-critical Scenarios |
API 6D Valve Mandatory Hydrostatic & Air Tests
| Test Item | Test Medium | Test Pressure | Purpose / Objective |
| Shell Test | Water (with corrosion inhibitors) | 1.5 x Rated Pressure | To verify the structural integrity and tightness of the valve body, bonnet castings/forgings, and joint connections. |
| High-Pressure Seat Test | Water | 1.1 x Rated Pressure | To confirm the sealing performance of the valve seats under high pressure (bi-directional or uni-directional). |
| Low-Pressure Seat Test | Air or Nitrogen | 80 psi (5.5 bar) | To simulate low-pressure conditions and detect minute bubble leakages that high-pressure tests might miss. |
GNEE API 6D Valve Workshop
