Carbon steel elbow is a kind of pipe fittings used to change the direction of the pipeline, made of carbon steel material (carbon content of 0.25% ~ 2.1%), by adding a small amount of manganese, silicon and other elements to enhance the strength and plasticity, widely used in high-pressure pipeline system. According to the angle, there are 45 ° and 90 ° 180 ° three of the most commonly used, in addition, according to the needs of the project also includes 60 ° and other non-normal angle elbow.