The present specification relates to a connecting pipe connected to pipes. In one embodiment, the connecting pipe may comprise: a first opening; a second opening; and a support groove which is vertical to the transverse cross section of the first opening, and which is disposed on a first center line passing through the center of the transverse cross section of the first opening. When the connecting pipe according to embodiments is connected to the pipes, the possibility of breakage or deformation, which can occur at a connecting portion of the connecting pipe and the pipe, can be minimized.

A method for refurbishing a pre-stressed concrete cylinder pipe (PCCP) comprises removing concrete from an existing inner surface of the PCCP at each end thereof to expose a metal core, cleaning the exposed metal core and depositing filler over the exposed metal core at each end of the PCCP to a thickness wherein the filler is substantially flush with the existing inner surface. One or more layers of carbon fibre reinforced polymer (CFRP) liner are applied to the existing inner surface of the PCCP and to the filler at each end of the PCCP. Each layer of CFRP liner conforms to the inner surface of the PCCP and the filler and remains substantially cylindrical with substantially constant diameter along a length of the PCCP with substantially unbent cylindrical ends. After curing all layer(s) of CFRP liner, each terminus of the layer(s) of CFRP liner is sealed.