| 摘要 |
<p>A bi-directional pipeline tool has a body (14) or location in a pipe (12). A seal element (16) is mounted on the body (14), the seal element (16) having oppositely directed seal portions (16a, 16b) with a first seal portion (16a) directed towards a first side (18) of the body (14) and a second seal portion (16b) directed towards a second side (20) of the body (14). A valve (28) is provided in the body (14), the valve (28) having a first port (32) for communicating with fluid on the first side (18), a second port (34) for communicating with fluid on the second side (20) and a third port (36) for providing access to a chamber between the seal element (16) and the body (14). In use, a pressure differential (22) is developed across the tool (10) between fluid (24) upstream of the tool (10) and fluid (26) downstream of the tool (10). The valve (28) permitting activation of the downstream seal portion, whichever of the portions (16a, 16b) is the downstream seal portion, by the upstream fluid pressure.</p> |
