There are a few things you need to know before cleaning a metal pipe with boiling water. First, make sure the metal pipe is properly cleaned by using a mild soap and water. Second, make sure the area around the metal pipe is clean by using a cloth or paper towel. Finally, use a pot or pan to heat up water and pour it over the area around the metal pipe. Be careful not to get any of the water on the metal pipe itself. After pouring enough water over the area, let it cool for about 10 minutes before using it to clean the metal pipe.