Patent 7255174 was granted and assigned to Baker Hughes on August, 2007 by the United States Patent and Trademark Office.
A sealing system for a flow tube keeps cement from getting around it to the flapper when the safety valve is in the open position. Seals are provided at opposed ends of the flow tube so that the power spring and the flapper will not get fouled with cement pumped through the flow tube in wells that are completed through a production string with the safety valve in place. The seals may be mounted to the flow tube or the surrounding body. A unique seal construction separates cement from the flapper behind the flow tube. The force acting on the flow tube to hold the valve open also helps to apply a force against the lower seal adjacent the flapper.