In the USA, 15mm is half-inch, and 22mm is three-quarters inch. Lengths of pipe nipples in these sizes range from one and a quarter/one and a half, to six inches, in half-inch increments.
A handheld bandsaw or a cutting torch, along a straight line made by a wraparound pipe marker.
High Carbon Steel.
Steel with a surface layer of dark coloured iron oxides used for low pressure hot water heating pipes. <<< Terrible answer
21`foot
iron and carbon