| 摘要 |
<p>The process is used to seal off a length of submarine pipe line (1) carrying oil or gas, permitting the replacement of eg. a defective valve. A terminal chamber (7) with an access hatch (8) is used to introduce a train of cable linked pneumatic plugs (11,12,13) which are sited above water either on the main pipe or a branch line. The plugs are connected (23) to a compressed gas source and are introduced with the pipe empty. Initially the leading plug (11) is inflated to become a sliding fit in the pipe bore, compressed inert gas then being used to propel it to the required location. The plug is then fully inflated to effect a seal, the remaining plug (12) or plugs are similarly inflated, and a counter pressure is created in the pipe vols. between plugs.</p> |
