Branch pipe liner bag and pipe lining method

A pipe lining method comprising the steps of:

• preparing a branch pipe liner bag comprising a tubular resin-absorbent material impregnated with an unhardened hardenable resin, a rigid flange formed at one end of said tubular resin-absorbent material, and a first set of bores formed through said flange and arranged about an inner periphery of said flange;
• and
• inserting said branch pipe liner bag into a main pipe;
• pressing said flange of said branch pipe liner bag onto the periphery of a branch pipe opening of said main pipe;
• inserting said branch pipe liner bag inside out into a branch pipe from the main pipe side to the ground by a fluid pressure with said flange remaining pressed onto the periphery of the branch pipe opening;
• hardening the hardenable resin impregnated in said branch liner bag with said branch pipe liner bag pressed onto the surface of the branch pipe;
• preparing a main pipe liner bag comprising a tubular resin-absorbent material impregnated with a hardenable resin;
• inserting said main pipe liner bag inside out into the inner main pipe by a fluid pressure;
• pressing said main pipe liner bag onto the inner surface of the main pipe and the first set of bores such that a portion of the hardenable resin in said main pipe liner bag enters into the first set of bores;
• hardening the hardenable resin impregnated in said main pipe liner bag and the first set of bores with said main pipe liner bag remaining pressed on the inner surface of the main pipe;
• after hardening said main pipe liner bag, cutting a portion of said main pipe liner bag covering the branch pipe opening.