| 摘要 |
<p>A filling head assembly (60) is suspended in the top of a casing section (20). Mud or other filling material is introduced into the casing section (20) via a fill line (50). Flow control means (71, 72) associated with the fill line (50) are responsive to an operator controllable means (100) including a pneumatic circuit (101). Sensing means (80) are coupled to said pneumatic circuit (101) so that the flow of filling material into the casing section (20) ceases when the filling material reached a predetermined level.</p> |
