Abstract: An expanding dual disc gate valve that can be used in applications requiring double block and bleed type systems. A stem is positioned in the center of a valve body with a first and second gate arranged on opposite side of the stem with respect to each other. The first and second gates are slidingly engaged with the stem so that the stem controls their movement between an open and a closed position with respect to an inlet and an outlet of the valve body. As the gates approach the closed position they encounter a shoulder of the valve body preventing further downward movement, whereby further force from the stem wedges the first and second gates outward to create a sealing arrangement with a seat ring of the valve body.