| 摘要 |
A method and system for repairing, replacing or installing an underground pipeline using an appropriate tool head. A coolant, preferably a cryogenic liquid, is injected in front of the tool head to embrittle or otherwise reduce the toughness of the material ahead of the tool head. Although suitable for use involving boring or drilling of the ground to install the underground pipeline, the method and system of this invention are particularly suitable for use in connection with pipe splitting and pipe bursting, where a pig disposed within the underground pipeline is connected with the appropriate tool head forming a space between the pig and the tool head into which the coolant is introduced. The pipe between the pig and the tool head is embrittled by the coolant, reducing the resistance of a pipe to splitting or bursting which, in turn, reduces the force required for the pig to pull the tool head as the pig is motivated through the pipe.
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