The present invention provides a method of manufacturing or repairing a pipe 1, the method comprising the steps of providing a pipe portion 2, the pipe portion having a channel 20 running along a surface of the pipe portion, the channel having an internal surface, placing a filler material 21 against the internal surface of the channel, and removing some of the filler material to provide a groove 22 inside the channel of the pipe portion. The present invention also provides a pipe 1 or pipe portion 2.