| 摘要 |
<p>The present invention provides a pipeline pig (10) comprising an elongate body (12) and annular front and rear supports (26,30) projecting radially from the body (12). Each support (26,30) has an upstream side and a downstream side, with the front support (26) including at least one first fluid passage (18) permitting fluid flow from the upstream side to the downstream side, and the rear support (30) including at least one second fluid passage (22) permitting fluid flow from the upstream side to the downstream side. The pig further comprises a launch valve (50) adapted to move from an open position to a closed position to close the at least one first fluid passage (18), and a control means adapted to control the closing of the launch valve (50). A launch trap for launching pigs into a pipeline is also provided.</p> |
