Diverter Tool and Associated Methods

A diverter tool reduces surge pressure when running casing into a wellbore. The tool is kept open while running the casing so surge pressure can pass out a bypass port. The tool is then closed with a ball that lands in a seat disposed in an interposed condition in a sleeve of the tool's housing. Fluid pressure applied against the seat in the interposed condition engaged with the ball overcomes a first fixture temporarily holding the sleeve open. The fluid pressure shifts the freed sleeve closed. Additional fluid pressure applied against the seat in the interposed condition engaged with the ball then overcomes a second fixture temporarily holding the seat in the sleeve. Once freed, the seat with the captured ball pivots from the interposed condition to a stowed condition to expose the internal bore of the sleeve to the longitudinal bore of the tool so additional cementing operations can be performed.