According to the valve body material, it has stainless steel, carbon steel and alloy steel elbow.
Material in carbon steel, referred standards as:
ASTM 234 WPB and WPC
ASTM A420 WPL6
MSS-SP-75 WPHY 42, 46, 52, 56, 60, 65 and 70
Stainless steel pipe elbow has higher strength and higher corrosion-resistances than carbon steel elbow. For general surface treatment, stainless steel elbow is used in high corrosion environment, such as chemical plants, offshore and gas pipelines. Surface treatment in 2B or mirror, these are used in food industries and sanitary purposes.
Material in stainless steel, referred standards as:
ASTM A403 WP 304/304L, 316/316L
ASTM A270
Stainless steel 90 degree elbow is a most common use of pipe elbow for stainless pipelines. Other than this is stainless steel 45 degree elbow, both of them in large requirements for butt weld, socket weld, and threaded connections.
Speaking of the forming of these steel pipe elbow, it has many steps. Even so , it is considered quite simple compared to other production processes.
First, we could weld the closed end of a polygonal circular shell or a polygonal sector shell. When the pipe inside filled with pressure medium, its cross section will change from a polygon to a tubular shape. Under internal pressure, the section will be a circular shell. Ring can be cut into four 90 degree elbows or six 60 degree elbow or any other size requirement. Due to advances in technology, the welding process can be applied in different application. For example, it is now possible to weld and manufacture larger diameter steel pipe elbow, especially large diameter that in long radius.
It is also possible to directly purchase the seamless pipe or welded pipe as the material of the steel elbow, then heat the pipe body with a heating machine, and then push the pipe body into different degrees of the mold to form the elbow shape.
In general, carbon steel has high carbon content, which will definitely give you more strength and hardness, but lower plasticity. Therefore, those that do not contain a large amount of alloy element are often referred to as carbon steel or straight carbon steel.
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