The Orifice Wellhead Control Valve of HS Orka

Abstract

In this paper the background of and the need for a certain valve, the Ellaloki, is described and its function and construction explained. When the pilot plant of the Svartsengi Powerplant started in November 1976, the flow from the wells was controlled with orifices, because gate valves could not be used for throttling. Back then, the only available method for changing the flow from a well, was by replacing the orifice plates, requiring a shut down of the well. During the first years of operation, a few types of control valves were tested. All of them failed, mostly because the two-phase jet cut through the valve body. A unique design valve was developed, consisting of an orifice, with a cone pushed into the hole, for varying the opening area. Several pictures will be shown describing this valve’s design and a few problems encountered during operation.