Self-cut valves cut into standard basic 15mm copper pipework *without the need to drain down.
* Facts applying to every self-cut valve, no matter where sourced
We recommended that the water supply to the pipe you are breaking into be turned off while you are installing the valve as in a very few odd exceptions the valve might fail to cut or to seal correctly. Failures can be caused by many reasons including incorrect fixing, unsuitable application or indeed valve failure.
It will only work on bare unpainted pristine standard 15mm Table "X" British copper.