| 摘要 |
A float valve 10 includes a valve body 12 for sealing engagement with a float sub 20 having threads for threaded engagement with an oilfield tubular. A valve element 40 includes a stem 50, 70 and a valve cone 52, 80 secured thereto. The valve cone is configured for sealing engagement with a seat 58 on the valve body. An elastomeric seal 48 may also be provided for sealing engagement with the valve body. The stem 50, 70 and the cone 52, 80 are preferably interconnected by a shrink-fit operation, wherein the cone is heated so that a cylindrical recess within the cone expands, while at least a front end 52, 72 of the stem 50, 70 is cooled so that its diameter is reduced. The shrink-fit operation forms a surprisingly reliable interconnection of a float valve stem with a cone, and substantially increases the life of the downhole float valve.
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