In the pipeline system, the elbow is a pipe fitting that changes the direction of the pipeline. According to the angle, there are three kinds of the most commonly used, 45 ° and 90 ° 180 °. In addition, according to engineering needs, it also includes other abnormal angles such as 60 °. The materials of the elbows are cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals and plastics. The ways to connect with the pipe are: direct welding (the most common way) flange connection, hot melt connection, electric fusion connection, screw connection and socket connection. According to the production process, it can be divided into: welding elbow, stamping elbow, push elbow, casting elbow, butt welding elbow, etc. Other names: 90 degree elbow, right angle bend, love and bend, etc.

The elbow is a kind of connecting pipe commonly used in plumbing installation. It is used for the connection of the pipe corner and used to change the direction of the pipe. Other names: 90 ° elbow, right angle bend, Elbow, stamping elbow, pressing elbow, machine elbow, welding elbow, etc. It is mainly used to connect two pipes with the same nominal diameter or different diameters to make the pipe turn 90 °, 45 °, 180 ° and various degrees. Bending radius less than or equal to 1.5 times the pipe diameter belongs to the elbow, and greater than 1.5 times the pipe diameter belongs to the elbow.

So what are the main points of making elbows?

1. The electrode should be kept dry. The titanium-calcium type should be dried at 150 ℃ for 1 hour, and the low-hydrogen type should be dried at 200-250 ℃ for 1 hour. The oily skin and other contaminants will prevent the weld from increasing the carbon content and affecting the quality of the weldment. When the elbow is welded, the carbide is precipitated by repeated heating, which reduces the corrosion resistance and mechanical properties. After welding, the hardening is large, and cracks are easy to occur. If the same type of electrode is used for welding, it must be preheated above 300 ℃ and slow-cooled at about 700 ℃ after welding. If the weldment cannot be heat-treated after welding, the chromium-nickel stainless steel electrode should be used.

2. In order to improve the corrosion resistance and weldability of stainless steel elbows, an appropriate amount of stability elements Ti, Nb, Mo, etc. are appropriately added. And tempering around 800 ℃ after welding. If the weldment cannot be heat-treated, the chromium-nickel stainless steel electrode should be used.