Buyers sourcing ball valves for high-pressure water, oil, and gas service frequently encounter the marking "1000 WOG" stamped on valve bodies .
What the Marking Means
● 1000 — maximum working pressure, in psi, at ambient temperature (generally up to ~100°F / 38°C)
● WOG — Water, Oil, Gas: the media types the valve is certified to handle at that pressure
The designation appears across ball valves, gate valves, and check valves, and is one of the first specifications engineers check when matching a valve to a system.
Pressure Drops as Temperature Rises
The 1000 psi figure is not a fixed ceiling across all operating conditions — it derates as temperature climbs, and the exact curve depends on body material:
| Temperature | Approx. Max Pressure |
| Ambient (~100°F / 38°C) | 1000 psi |
| 200°F (93°C) | ~800 psi |
| 300°F (149°C) | ~600 psi |
Stainless steel valves generally tolerate higher temperatures before derating becomes severe than carbon steel equivalents.
Where WOG Applies — and Where It Doesn't
Covered:
● Compressed air, natural gas, inert gases
● High-pressure water lines
● Hydraulic and petroleum-based oils
Not covered:
● Steam — requires a separate WSP (Water Steam Pressure) rating, typically much lower than the WOG figure on the same valve. A valve marked "1000 WOG / 500 WSP" can only handle 500 psi of steam despite its 1000 psi cold-water rating.
● Highly corrosive chemicals, unless wetted materials are separately verified as compatible
● Cryogenic or ultra-high-pressure service beyond ANSI Class 1500
Typical Applications
● Hydraulic and industrial water systems
● Oilfield wellheads and pipelines
● Fire suppression and booster pump systems
● Compressed-air lines in manufacturing plants
Steam lines, highly corrosive process fluids, and extreme-temperature service fall outside the intended scope and call for valves with different ratings entirely.
Four Checks Before Buying
1. Body material — stainless steel for corrosion resistance; carbon steel for strength with a protective coating; brass only in lower-pressure variants
2. End connection type — threaded (NPT/BSP), flanged, or welded
3. Temperature derating specific to the chosen material
4. Certifications — e.g. API 6D for pipeline service, API 607/6FA fire-safe ratings for critical oil and gas applications
One Common Misreading
1000 WOG is not equivalent to an ANSI 1000 class rating, which applies at elevated temperatures rather than ambient conditions. Exceeding the rated pressure risks valve rupture or leakage regardless of application.
