Abstract: A method of lining an existing pipe by pulling through it a collapsible, flexible, lay-flat liner having an innermost layer of impervious, elastomeric material which is compatible with the fluid to be carried by the pipe, a textile reinforcing intermediate layer, and an external protective layer of elastomeric material. The liner has an external circumference slightly less than the internal circumference of the pipe and is such that flow of fluid through the liner after the installation thereof expands the liner into non-binding contact with the internal surface of the pipe. The peripheral extension (diametral swell) of the liner at the intended working pressure of the relined pipe should be less than 10% and preferably less than 5%.