WOG Rating

Valves carry two ratings: WOG and WSP (sometimes SWP). WOG stands for the water, oil, and gas rating for the valve and reflects the maximum pressure capability of the valve at 100 F. WSP stands for working steam pressure and reflects the maximum pressure rating for the valve at the highest temperature rating. Working pressure for all equipment decreases as pressures increase. The WOG rating is always higher than the WSP rating for a valve or fitting.

API Spec 6A valves (Specification for Wellhead and Christmas Tree Equipment)carry the WOG mark. In this spec the Water Oil Gas pressure rating is the working pressure of the valve at whatever temp class it is in. These valves come in 2,000, 3,000, 5,000, 10,000 15,000 and 20,000 WOG ratings with temperature classes from -75F to 350F.