Fill and Circulate Tool (hereafter referred to as FAC Tool) is a surface tool used during the casing running operation. The FAC Tool is designed to both fill the casing with drilling fluid while running it in the hole and to enable quick circulation of the casing string at any time without installation of a casing swage. The FAC Tool has features with easy â??to- use , safe and reliable , no leakage and so on, which lightens labor intensity of workers greatly and improves operation environment of well. The FAC Tool is composed of ten parts (shown in figure) , whose main function of components are below: 1. Drill Pipe Connector: The FAC Tool built for top drive rigs connects to the drill pipe threads of the rigâ??s top drive unit via the Drill Pipe Connector. The threads of the Drill Pipe Connector are standard 4 1/2 IF, but crossovers are available for other drill pipe threads. 2. Extension: For applications where long elevator links are used, Extensions are placed between the Drill Pipe Connector and the Mandrel. On the Extension are two Pad Eyes that make it easy to manipulate the Tool around the Rig during rig up or rig down. Also, while the Tool is in use, a Safety Cable attaches to one of the Pad Eyes in the event the Tool should accidentally come loose from the top drive. In place of the Extensions, a Drill Pipe Pup can be used between the top drive connection and the Drill Pipe Connector instead of extension. 3. Mandrel: The Mandrel houses the specially designed Seal Assembly that is used to seal off the casing string. The Seal Assembly has three parts: the Seal Retainer, the Sealing Element, and the Gauge Ring. 4. Seal Retainer: Aluminum part that keeps (retains) the Sealing Element from being extruded upward while circulating. 5. Sealing Element: Elastomeric Seal that seals off the casing for circulation. It is hollow so circulation pressure can energize the seal it creates against the casing bore. 6. Gauge Ring: Tapered Aluminum piece that guides the Seal Assembly into the pipe and has holes to allow energizing pressure into the Sealing Element. 7. Retainer Sub: The Seal Assembly is held in place with the flexible hose. 8. Flexible Hose: The Retainer Sub is also used to connect a high pressure Flexible Hose. This Hose prevents any hard stack out between the FAC Tool and the casing and compensates for misalignment and casing movement during make up. 9. Mud Saver Valve: Below the Flexible Hose is the heart of the FAC Tool, the Mud Saver Valve. It is essentially a two-way check valve. This Valve opens with pressure when the mud pump is turned on and closes when the mud pump is turned off. It also permits flow in the upward direction for releasing pressure.