Slip bottom connection 1.API 6A certificate 2.CE certifiicate 3.Using BT ... surface casing, design with BT type casing seal ring. *The connection is firm and the seal is reliable.•For TDC type ... casing head and surface casing connection, by tightening the bolt to hold the casing slip tooth ... •Material class: AA,BB,CC,DD,EE,FF Slip Bottom Connection