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Abstract

An apparatus for repairing an underground pipe includes a mandrel having a first expander capable of extending and retracting in a radial direction, a system for causing radial expansion and retraction of the expander when in position at a pipe location in need of repair, a resilient stiffening frame disposable in a tubular configuration outside of the expander, such that the expander can be used to expand the frame into contact with the inside of the pipe, and a suitable arrangement for confining a flowable cement between the expander and the inside of the pipe to form a repair band upon setting of the cement. In a preferred form of the invention, the expander comprises a central inflatable bladder, and the system controlling radial extension and retraction of the expander includes a line supplying pressurized air to the bladder.

First Claim