WOG stands for Water, Oil, Gas. A marking such as 1000 WOG or 2000 WOG states the valve’s maximum working pressure for water, oil, and gas under cold, non-shock conditions. The WOG pressure rating is a useful first-pass way to compare valves, but it is not proof that a valve suits your complete operating conditions.
This guide explains what the WOG number covers, what it leaves out, and what to confirm with the manufacturer before you select a valve based on it.
What 1000 WOG and 2000 WOG Actually Mean
1000 WOG and 2000 WOG are cold, non-shock working pressure classes for water, oil, and gas service. A 2000 WOG valve carries a higher cold working pressure rating than a 1000 WOG valve. That is the entire difference the marking communicates.
Two words in that definition carry most of the weight. Cold means the rating applies at ambient temperature, not at elevated service temperatures. Non-shock means the rating assumes steady pressure, with no allowance for water hammer, pulsation, or surge events. The figure is conventionally read in pounds per square inch (psi), and the same idea is often written as CWP, short for cold working pressure. Rating practice for threaded-end ball valves is covered by industry documents such as MSS SP-110 from the Manufacturers Standardization Society (MSS).
You will find WOG markings mainly on threaded and other non-flanged valves. For example, our two-piece ball valve with camlock quick coupling is rated 1000 WOG.
A higher WOG class is not automatically the better choice. It tells you the valve starts from a higher cold pressure rating, nothing more. A 2000 WOG valve is not thereby qualified for steam, for high temperature, or for surge-prone lines. If your service pressure sits comfortably under 1000 psi at ambient temperature, paying for a 2000 WOG body buys you margin, not suitability for a different kind of duty.
Looking for the valve itself?
One-Piece Ball Valve, 1000 WOG — 304/316 stainless, PT thread, 1/4″–3″
High Pressure Ball Valve, 2000 WOG — 2-piece 316 stainless, full port, 1/4″–2″
What the WOG Pressure Rating Does Not Tell You
The WOG pressure rating answers exactly one question: how much steady pressure the valve can work at with water, oil, or gas in the cold state. Every other question about your application remains open. The table below lists the questions buyers most often assume the WOG number answers, when in fact it does not.
| Operating question | Answered by the WOG number? | What actually governs it |
|---|---|---|
| Steam service | No | Seal configuration, confirmed model, and the actual steam pressure and temperature |
| Elevated temperature | No | Seat and seal materials and the valve’s behavior at that temperature |
| Pressure-temperature relationship | No | A pressure-temperature rating for the specific valve, which WOG is not |
| Water hammer and pulsation | No | WOG assumes non-shock conditions; surge duty needs a system-level review |
| Vacuum duty | No | Confirmation from the manufacturer for the specific model and configuration |
| Chemical compatibility | No | Body and seat materials checked against the actual fluid, concentration, and temperature |
| Required leakage performance | No | The shutoff duty your application requires, confirmed against the valve’s sealing design |
Put simply: WOG is not a steam rating, not a design pressure, and not a pressure-temperature curve. Treat it as one line on the datasheet, not as the datasheet.
Steam and High Temperature: Check the Seal Configuration
WOG does not qualify a valve for steam. Steam combines pressure with high temperature, and saturated steam pressure climbs steeply as temperature rises, as standard saturated steam property tables show. A rating defined for the cold state simply does not describe that situation.
What decides steam suitability is the seal configuration, not the WOG number. Selected ball valve models in our range, when built with the specified graphite seal configuration, can be used for steam service up to a maximum of 180°C. This applies only to the models confirmed as configurable with graphite seals. Even for those models, confirm the actual steam pressure at your operating temperature, the exact model, and the complete configuration before ordering. Our guide on why ball valves leak covers the graphite-sealed configuration in more detail.
Two assumptions to avoid. First, do not assume that every 1000 WOG or 2000 WOG valve can handle steam; most standard configurations cannot. Second, do not assume that a graphite-sealed valve tolerates 180°C steam at any pressure; the temperature limit and the allowable pressure must be confirmed together for the specific model.
PTFE-seated and graphite-sealed builds are different configurations. A datasheet that lists PTFE seats does not imply the graphite steam capability, and the two should never be treated as interchangeable.
Why Material and End Connection Still Matter
Even when the pressure class fits, the body material, seat material, and end connection decide whether the valve actually works in your line.
Body material. The WOG number says nothing about corrosion. Stainless steel grade selection depends on the fluid: 316 resists chloride pitting better than 304 because of its molybdenum content, which is why chloride-bearing media push the choice toward 316. That does not make 316 universally suitable for every chloride or chemical service; concentration and temperature still decide, and the combination should be confirmed case by case.
Seat and seal materials. As covered above, the seat and seal package sets the temperature capability and the steam answer. Two valves with identical WOG markings can have very different temperature limits.
End connection. WOG markings belong to threaded and similar non-flanged valves. Flanged ball valves are rated by flange class instead, such as JIS 10K/20K or ANSI Class 150/300, following JIS flange standards and the pressure-temperature rating approach defined in standards such as ASME B16.34. If you are comparing a threaded 1000 WOG valve against a flanged ball valve, you are comparing two different rating systems, and the numbers are not directly interchangeable.
Installation. Thread engagement, gasket and flange makeup, and welding quality all sit outside the valve rating yet directly affect whether the joint holds the rated pressure in practice.
What to Send Before Requesting a WOG-Rated Valve
The fastest way to get a correct quotation is to describe the duty, not just the pressure class. Send the following with your inquiry, and the supplier can confirm whether a 1000 WOG valve, a 2000 WOG valve, or a different configuration entirely is the right fit.
| What to send | Why it matters |
|---|---|
| Fluid and concentration | Determines body and seat material compatibility |
| Operating and maximum temperature | WOG is a cold rating; temperature drives the seal configuration |
| Operating and maximum pressure | Confirms whether the pressure class actually covers your worst case |
| Whether steam, water hammer, pulsation or vacuum is involved | These duties sit outside the WOG definition and need separate confirmation |
| Valve size and end connection | Decides the rating system (WOG vs flange class) and the available models |
| Required shutoff duty | Leakage performance is not part of the WOG marking |
| Required seal configuration | PTFE and graphite builds have different capabilities and must be specified |
| Project specification | Lets the supplier check compliance items you may not have listed |
If any of these are still unknown, say so in the inquiry. An open question stated clearly is far cheaper than a wrong assumption discovered after installation. Send your operating conditions to sales@ballvalves.tw and we will confirm which valve and which seal configuration actually fit the duty.
Frequently Asked Questions
Is 2000 WOG always better than 1000 WOG?
No. 2000 WOG only means a higher cold, non-shock working pressure rating for water, oil, and gas. It does not make the valve more suitable for steam, high temperature, surge conditions, or aggressive media. If your line runs well below 1000 psi at ambient temperature, a 1000 WOG valve with the right materials and seal configuration is the better match than a 2000 WOG valve with the wrong ones. Choose by the full operating conditions, then check that the pressure class covers your maximum pressure.
Does 1000 WOG mean the valve is suitable for steam?
No. WOG is a cold, non-shock rating for water, oil, and gas, and steam is neither cold nor covered by that definition. Steam suitability depends on the seal configuration and the specific model. In our range, only selected models confirmed as configurable with the specified graphite seal configuration can be used for steam service, up to a maximum of 180°C, and the actual steam pressure, model, and configuration still need to be confirmed before ordering.
Can a graphite-sealed valve handle 180°C steam at any pressure?
No. 180°C is the maximum steam service temperature for the specified models in the confirmed graphite seal configuration; it is not a blanket approval at every pressure. The allowable steam pressure at your operating temperature, the exact model, and the complete configuration must be confirmed together for the specific application. Always state the actual steam pressure and temperature in your inquiry rather than assuming the temperature limit alone settles the question.
Does WOG tell me whether 316 is suitable for my chemical?
No. The WOG number is a pressure rating and carries no information about chemical compatibility. 316 stainless steel resists chloride pitting better than 304 thanks to its molybdenum content, but that does not make it suitable for every chemical, chloride level, or temperature. Compatibility has to be checked against the actual fluid, its concentration, and the operating temperature. Send those details with your inquiry so the material choice can be confirmed rather than assumed.
What is the difference between WOG and a pressure-temperature rating?
WOG is a single number that applies only in the cold, non-shock state. A pressure-temperature rating, such as the class-based ratings defined in ASME B16.34, specifies the allowable pressure across a range of temperatures, so you can read off the limit at your actual operating temperature. WOG gives you no such curve. If your service runs at elevated temperature, you need the valve’s confirmed capability at that temperature, not the WOG figure.