| 摘要 |
Methods for releasably plugging off a section of a pipe line and apparatuses for practicing or carrying out the methods are disclosed. An apparatus comprises one or more pigs, each pig having an inflatable ring therearound, inert gas therein for inflating the ring, and a remote thermal command signal receiver for initiation of expansion of the pigs responsive to a remote thermal command signal of one temperature generated by a generator at the ends of the pipe section to be sealed off for sealing the pigs in the pipe as they reach their respective pipe section termini. The remote command signals comprises thermal energy of precise temperatures.
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