Welded joints are produced in two steel and alloy forms. They are used in water, gas, steam, air and other different industries. They are divided into two kinds of seamless and Mannesmann based on the kind of lines function pressure and the kind of fluid and thickness of lines’ pipe. They are divided into following groups based on different manufacturing ways; welded knee, welded triode, welded cope, welded bushing, welded convertor, welded nipple, welded intersection.