05586580 is referenced by 5 patents and cites 21 patents.

An apparatus and method for sealing joints and leaks in pipes is provided. The apparatus is particularly useful for sealing leaking at joints in underground gas mains. A sealant applicator in the form of a push snake is provided which may be inserted into the pipe through a standard tap fitting. Thick or viscous sealant is pumped down through the snake and is thereafter applied radially outward to the inside surfaces of the pipe by a spinning applicator tip. Flaps may be attached to the spinning applicator tip so that the thick sealant is trowelled into place. The applicator tip may be rotated with compressed gas which may be compressed methane gas drawn from the gas main. A centralizer is preferably employed to centralize the applicator head in place during application of the sealant. The flaps may also be used to clean the pipe prior to the application of the sealant.

Title
Apparatus and method for internally sealing pipes
Application Number
8/415267
Publication Number
5586580
Application Date
April 3, 1995
Publication Date
December 24, 1996
Inventor
David I Freed
Waltham
MA, US
Allan T Fisk
Needham
MA, US
Agent
Hill Steadman & Simpson
Assignee
Gas Research Institute
IL, US
IPC
F16L 55/162
View Original Source