Piping and Valve Knowledge: [Weekly Topic] What are the requirements for hot-bent and cold-bent pipes? (12.26---12.31)
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This post was last edited by security on 2010-12-29 at 13:36; making bends on site is an essential part of the process installation. I would like to ask what requirements there are for pipelines regarding hot bending and cold bending: pipe diameter? Material? Pipe diameter? Angle (that is, how many times D)? Length? What are the requirements? You can find them there Everyone, share your opinions!
In pipeline engineering, depending on the manufacturing method, they can be classified into bent bends by bending, bent bends by stamping, and bent bends by welding. Warm bending is further divided into cold bending and hot bending; it offers advantages such as good tensile and elastic properties, high pressure resistance, and low resistance, which is why it is widely used. Cold bending of large elbows involves using machinery to bend the pipes at room temperature; it does not require heating equipment, there is no need to fill the pipes with sand, and the process is simple to operate. Hot bending for large curves is a relatively primitive manufacturing method; it involves filling the pipe with sand and then heating the pipe to bend it into large curves. This method is quite flexible, but it is not efficient, results in significant energy waste, and has high costs. Currently, this method is less frequently used for bending carbon steel, but it offers clear advantages in bending certain non-ferrous metal pipes and plastic pipes. The main steps of this method are: sand filling, heating, bending, and sand removal. Due to the different stresses on the pipeline, the requirements for changes in the wall thickness during bending also vary. 1. When the pipeline is under external pressure (such as in a jacketed tube setup): it is required that the difference between the maximum and minimum outer diameters at any cross-section of the pipeline after bending shall not be greater than 8% of the pipeline’s nominal outer diameter ； 2. Internal pressure on pipes: It is required that the difference between the maximum and minimum outer diameters at any cross-section of the pipe after bending shall not be greater than 3% of the pipe’s nominal outer diameter. The relevant technical requirements can be found in GB50316.
GB/T20801.4－2006 is Part 4 of the \"Code for Pressure Piping – Industrial Piping\", and it specifies the basic requirements for the fabrication and installation of industrial metal pressure piping. The latest version, very detailed.