Galvanized pipes or plumbing pipes are caused by the introduction of black steel pipes through the zinc plating process to prevent rusting.
This type of steel pipe is more durable than general steel, which is mostly used in plumbing systems with control of lead not more than 0.03% which is the export standard.
The cooling system of air conditioners in buildings and other general applications is available in 3 types: red, expected (very thick), blue expected, yellow expected (thin).