A serpentine tube is a tube that twists and turns many times in a plane. The convection heating surface of the boiler, such
as economizer, superheater and reheater, mostly adopts the serpentine tube structure with horizontal and vertical layout.
The vertical coil is easy to accumulate water in the pipe after the boiler shutdown, but it is easy to support and hoist.
The superheater, reheater and economizer of the boiler adopt serpentine tube heating surface. Due to a series of characteristics such as large number, different bending radius and many welded joints, the manufacturing process of serpentine heating surface is more complex and
the productivity is lower. In recent years, in order to change this backward production appearance, China's major boiler plants
have taken a series of measures in design and technology to improve the universality of product parts and components, creating necessary conditions for the mechanization, automation and organization of automatic production lines of serpentine pipe
production. At present, China's major boiler plants have adopted automatic production lines with program control for the manufacture of coil heating surfaces.
Differences
| Type | Advantages | Disadvantages | Supporting method |
| Pendant-type | 1.Firm structural support | 1. Flow blockage by condensed steam 2. Needs slow restart to purge the water that accumulates in the bottom. | supported from above |
| Inverted-type | 1.Proper drainage of the condensed steam | 1. Lack the structural rigidity, especially in high speed gas flow | Supported from below |
| Horizontal -type | 1. Proper drainage 2. Good structural rigidity. | 1. They do not view the flam directly so they are mainly from the convective type | Usually supported in the vertical gas ducts parallel to the main furnace. |
