Heat exchanger  is  a heat exchanging equipment which is widely used in petroleum chemical, metallurgy, electric power, refining, chemical production line, the number of heat exchangers has occupied around 40% of the total equipment, and 30%-45% of  the total investment. In the recent years, the usage has expanded due to the development of energy saving technology. It achieves great economic benefit by reusing the heat and the lower-temperature exchange. And  the  tube heat exchangers are the most widely used of the heat exchanger series.