The reducing elbow is also called the taper bend, the diameter bend, the irregular bend. The different diameter elbow is used to press the plate with the same material of the pipe material into half a circular bend, and then the two half ring elbow is formed for the welding forming. Due to the different welding standards of various pipes, usually the semi-finished products are manufactured according to the group, and the site construction is welded according to the weld grade of the pipeline. Therefore, it is also known as the two-part welding elbow.

Reducing elbow use: connect two different pipe diameter, the pipeline for 90 ° turn at the same time make the size smaller. The process of production is produced by the process of reducing the strip with the entire bend. The effect is to change the diameter of the pipe when you make a 90-degree turn. The function of the size head is the same, but the size head cannot be turned. The price is about twice as high as the elbow. In some construction sites, a bend and a size head are welded together to replace the product. Its materials are carbon steel, stainless steel, alloy steel, PVC, cast steel etc. Common standards include GB/t12459-2005 and GB/T13401-2005.

The international standard is the national standard of the United States, ANSIB16.9 and 16.28. The outside diameter of the standard is 1/2 "-80", and the average 24 is the raw material with seamless steel tube, and 26 to 80 is used to press the steel plate for welding. Wall thickness can reach 60mm, small to 1.24mm. The steel is used for carbon steel (20 #), alloy steel and stainless steel, with 24 steel types. The CrMo steel used on boiler is like 15Cr, which is larger in quantity.