The most commonly used customers are stainless steel 304. The working environment is generally divided into dry burning and liquid heating. If it is dry burning, such as for oven, air duct heater, it can be made of carbon steel or stainless steel 304. If it is heated liquid, if it is water, use electric heating tube. This stainless steel is generally made of stainless steel 304. If it is oil, it can be made of carbon steel or stainless steel 304. If it is a weak acid alkaline liquid, it can be made of stainless steel 316. If there is strong acid in the liquid, stainless steel 316, Teflon or even titanium tube should be used.