... or roller roller bit can drill Application: Use the flap valve automatic fill slurry collar, during the casing operation ,the slurry ... time of casing.7,Special cut structure of the flap valve keep open. This shear structure of both a good seal ... collar , the bottom of the guide shoe to the right series to ensure that flow is not cut and the short ... .757 5/826.4047.108.5006.86412.00 Flap Valve Float Collar