In This Article
- 1.API 600 Design Features
- 2.API 600 Body Material Classes
- 3.API 600 Trim Numbering System
- 4.API 600 vs API 6D vs API 602
API 600 — 'Steel Gate Valves — Flanged and Butt-Welding Ends, Bolted Bonnets' — is the most widely specified standard for steel gate valves in oil refinery, petrochemical, and process plant service. It covers valves from DN50 to DN600 (2" to 24"), in pressure classes Class 150 to Class 2500. API 600 specifies the bolted bonnet design (as opposed to the pressure-seal bonnet used in API 603 for higher-pressure service), the outside-screw-and-yoke (OS&Y) rising stem configuration, and a detailed trim material numbering system.
API 600 Design Features
- Bolted bonnet: the bonnet is secured to the body by bolts/studs — allows easy disassembly for inspection and maintenance without special tooling
- Outside-screw-and-yoke (OS&Y) rising stem: the stem rises out of the valve body as the gate rises, providing a visual position indicator and preventing stem thread contamination by process fluid
- Full-bore (full-port) design: the valve bore matches the pipe bore, allowing pigging and minimising pressure drop
- Wedge gate: the standard closure element is a flexible or solid wedge that seats on inclined body seats — provides tight shut-off with wedging action
- Backseat: a seat on the stem allows the packing to be replaced under pressure with the valve fully open (important for maintenance)
- Pressure class: Class 150, 300, 600, 900, 1500, 2500 to ASME B16.34 pressure-temperature ratings
API 600 Body Material Classes
| Material | ASTM Grade | Temp Range | Application |
|---|---|---|---|
| Carbon Steel | A216 WCB | -29°C to +425°C | General refinery service, oil & gas, water, steam to 425°C |
| Low-temp Carbon Steel | A352 LCB/LCC | -46°C to +345°C | Low-temperature service, LPG, propane, LNG approach piping |
| 1.25Cr-0.5Mo Alloy Steel | A217 WC6 | -29°C to +540°C | High-temperature steam, boiler feedwater, Class 600-2500 refinery |
| 2.25Cr-1Mo Alloy Steel | A217 WC9 | -29°C to +593°C | Ultra-high-temperature service, power plant main steam, HRSG |
| 5Cr-0.5Mo Alloy Steel | A217 C5 | -29°C to +650°C | Hydrogen, high-temp refinery process — catalytic reforming, hydrocracking |
| Stainless Steel 304 | A351 CF8 | -254°C to +425°C | Cryogenic, chemical, food, pharmaceutical |
| Stainless Steel 316 | A351 CF8M | -254°C to +425°C | Corrosive service, seawater, marine, chemical, pharmaceutical |
| Duplex SS (F51) | A995 Grade 4A | -46°C to +315°C | Seawater, chloride environments, offshore topside and subsea |
API 600 Trim Numbering System
API 600 defines 'trim' as the combination of seat rings, stem, and wedge facing material. The trim number is critical for specifying the correct materials for the service fluid:
| Trim No. | Seat Material | Stem Material | Backseat | Application |
|---|---|---|---|---|
| Trim 8 | 13Cr (410SS) hard-faced | 410SS | 410SS | Standard for most general-service WCB valves — oil, gas, steam |
| Trim 12 | 316SS | 316SS | 316SS | Corrosive chemical service, seawater, chlorides; standard for CF8M body |
| Trim 13 | 316SS hard-faced (Stellite) | 316SS | 316SS | Erosive and corrosive service — refinery, chemical, high-velocity steam |
| Trim 5 | 410SS Stellite-faced seats | 410SS | 410SS | High-temp steam service with WC6/WC9 body |
| Trim 16 | Duplex SS 2205 | Duplex SS | Duplex SS | Offshore, subsea, highly corrosive environments |
API 600 vs API 6D vs API 602
| Standard | Application | Size Range | Key Difference |
|---|---|---|---|
| API 600 | Refinery, process plant isolation | DN50–DN600 (2"–24") | Bolted bonnet, OS&Y, wide material range |
| API 6D | Pipeline (oil/gas transmission) | DN25–DN1500 (1"–60") | Pipeline-specific: through-conduit, bidirectional, pigging-compatible |
| API 602 | Small bore, high-pressure | DN8–DN40 (⅜"–1½") | Pressure-seal bonnet, higher pressure ratings to Class 2500, compact design |
| API 603 | High-temp, high-pressure | DN25–DN600 (1"–24") | Pressure-seal bonnet, no bolted bonnet, ASME B16.34 Class 1500/2500 |
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