A short cylindrical section of steel which is placed in the casing string above the guide shoe. The float collar usually incorporates a bail or spring-loaded backpressure valve which prevents wellbore fluid from entering the casing while the pipe is lowered in the well. This makes the casing buoyant, thereby reducing the derrick stress while running casing.
Source: API BULLETIN E3, Environmental Guidance Document: Well Abandonment and Inactive Well Practices for U.S. Exploration and Production Operations, First Edition, January 1993 (Reaffirmed June 2000). Global Standards