This material was very popular from the mid 60’s to the mid 70’s. Builders loved it as it came in long lengths, could be cut with a wood saw and dry jointed using a chamfered double collar. Compared to the main alternative at the time - cement jointed socketed clay pipe - it was great.
However, it’s durability was questioned as long ago as 1976 and Building Inspectors started to discourage it’s use. Their pessimism has since been vindicated as much of the pitch-fibre pipe that we see these days is blistered or it has become oval.
We can ream out the blisters and reform the pipe using a variety of methods. The reformed pitch-fibre pipe is then lined using Brawoliner.
Brawoliner is particularly suited to this application as it has a high strength and the hot curing process temporally softens the pitch-fibre pipe to smooth out the scars and marks left after the blisters have been reamed out.