Tokyo Gas Company Limited

Takashi Shigefuji

Shigeru Toyoda

Masaaki Itagaki

Shuichi Yagi

Tadao Yahata

Shinobu Satake

There is provided a method of lining the internal surface of a pipe involving a larger diameter portion, said method comprising the steps of inserting a first pig into the pipe from an open end thereof, said first pig being a spherical body made of a resilient material having a diameter larger than the pipe inner diameter and having a number of grooves formed on the surface thereof for permitting air escape, injecting behind the first pig a necessary amount of resin into the pipe, inserting behind the resin a second pig into the pipe, said second pig having a diameter smaller than the pipe inner diameter such that a resin lining layer having a desired thickness may be formed on the internal surface of the pipe, providing a positive pressure and applying the positive pressure behind the second pig in the pipe, and causing the first pig, the resin and the second pig to move through the pipe along the entire length thereof by the positive pressure, so as to form a resin lining layer on the internal surface of the pipe by means of the second pig.

Methods of lining the internal surface of a pipe

There is provided a method of lining an existing underground main pipe involving a branch pipe. The method comprises injecting a necessary amount of resin into the branch pipe from an open end thereof, introducing behind the resin a pig apparatus into the branch pipe, applying a positive pressure behind the resin and pig apparatus in the branch pipe to cause the resin and pig apparatus to move forward until the entire internal surface of the branch pipe is lined with the resin by means of the pig apparatus and until the pig apparatus reaches and slightly passes beyond a branching position where the branch pipe is branching from the main pipe, applying a negative pressure behind the pig apparatus in the branch pipe to cause the pig apparatus to stop at the branching position such that the branch pipe is completely isolated from the main pipe, injecting a necessary amount of resin into the main pipe from an open end thereof, inserting behind the resin a lining pig into the main pipe, applying a positive pressure behind the resin and lining pig in the main pipe to cause the resin and lining pig to move through the main pipe along the entire length thereof, so as to form a resin lining layer on the internal surface of the main pipe.

Growing community of inventors

Tokyo, Japan

Takashi Shigefuji