Method of installing an interior by-pass liner

摘要

Interior by-pass for underground gas service line is installed from building basement without need for excavation, and has a tightenable adapter attached on each end of the by-pass tubing to connect and seal the tubing to the interior periphery of the service line. Each adapter provides a pair of spaced-apart expanded sealing gaskets between the tubing and the service line, and a gas-leakage passage extending from the interior of the tubular adapter to the exterior spacing between the adapter gasket pair. Temporary gas-tight plugs are provided at respective locations between each leakage passage and the adjacent end of the by-pass tubing, and compressed natural gas test-pressure is applied within the tubing. Via both of the referred to leakage passages, the test pressure is exerted against all of the gasket seals to confirm gas-tightness thereof. Techniques are described for installing each adapter and the by-pass tubing, working only from the service end of the line, including installation of the service end adapter prior to the blind end adapter; the use of temporary gas-inflation bags to permit installation of the by-pass in the face of service gas flow; and structures on each adapter to fully expand the innermost gasket of each pair before the outermost gasket is expanded.