Cutting Vitreous Enamel Stove Pipe
The manufacturer of our vitreous enamel stove pipe does not recommend cutting the lengths at all. The reasoning behind this is that it's the vitreous enamel coating that protects the mild steel pipe underneath from corrosion and attack from combustion deposits. Once you cut the pipe, you expose the mild steel pipe.

Adjustable lengths are available to assist in achieving the exact required length.

However, it's worth mentioning that many people do actually cut the pipe to length. You would normally cut the socket end of the pipe, which means that the next component would slide inside the cut length, thereby ensuring that the exposed mild steel pipe does not come into contact with combustion products. If you should decide to do this, please be aware that it will invalidate any warranty on the pipe.