| 摘要 |
A concentrically multi-shafted apparatus compresses a compressible stopper to effect a seal in a through-hole of a main utility line to permit a substantially leak-free removal and replacement of a service saddle or a service seal. Counter rotation of concentric shafts, depending upon the direction of rotation, increases or decreases an axial load on the compressible stopper. The external concentric shaft is in sealing engagement with a housing which, when coupled to a utility customer's gate valve permits a main line through-hole to be sealed by the compressible stopper without leakage of water or gas. Once the through-hole is sealed, the service saddle can easily be removed and replaced.
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