A float valve is used in a tubular having a through-bore for flow. The tubular can be a casing joint, a casing pup joint, a housing or a shell of a float collar/shoe, or other tubular element. A sleeve of drillable material is expanded inside the tubular. Sealing and/or anchor elements on the exterior of the sleeve can engage inside the tubular. Caps composed of drillable material are disposed on ends of the sleeve and have passages connected to ends of a flow tube. The flow tub is also composed of drillable material and has a bore therethrough for flow. A valve composed of drillable material is disposed in the passage of one of the caps and is configured to control the flow in the tubing through the flow tube.