Welding hoses (also known as welding gas hoses) are used to transport welding gases to welding equipment. Grade R welding hoses are designed for carrying acetylene or oxygen. Grade T welding hoses are ideal for transporting alternate fuels such as liquid propane, natural gas, and propylene, but they can also be used with acetylene. Inert gas welding hoses can be used to carry shielding gas or water to a welding torch. Twin-line hoses have one hose for oxygen and another hose for welding fuel gases. Single-line hoses come with just one hose and are commonly used in applications where space is too limited for a twin-line hose or where gas sources are separated.