Steel Structure Design of High Frequency Longitudinal Welded Pipe

Posted by chase Liu on November 23rd, 2022

Different from ordinary welded pipes, high-frequency straight seam welded pipes (ERW pipes) are hot-rolled coils formed by a forming machine, using the skin effect and proximity effect of high-frequency current to heat and melt the edge of the tube blank. Under the action of squeeze rollers, pressure welding is carried out to realize the production of welded pipes. Mainly used in water supply engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction, etc.

Steel tube structures can save about 20% of steel in industrial buildings and about 50% in tower structures compared to structures made with open sections. According to the stress state of the component, supply conditions, production and processing conditions and cost, the structure of the steel pipe can be a round pipe structure or a rectangular pipe structure, or a mixture of the two steel pipes. When used in combination, generally the chord is a rectangular tube, and the web is a round tube. Sometimes the chords can also be made of I-beams or H-beams, and the ribs can be rectangular or round tubes.

Advantages of high frequency longitudinal seam welded pipe:

1) The geometric characteristics of the straight seam steel pipe section are good, the pipe wall is generally thin, the section material is distributed around the center of mass, the section radius of gyration is large, and the torsional rigidity is large. As a compression, bending and two-way bending member, its bearing capacity is high, and the straightness and cross-sectional size of the cold-formed pipe are more accurate than the cross-section of the hot-rolled opening;

2) In terms of anti-hydrodynamic properties, the cross-section of the round pipe is the best, and the flow effect of wind and water is greatly reduced. The cross-section of a rectangular tube is similar in this respect;

3) The steel pipe is a closed section; in the case of the same average thickness and cross-sectional area, the exposed surface area is about 50% to 60% of the opening part, which is beneficial to prevent corrosion and save paint;

4) The connection of nodes is suitable for direct welding, which can save labor and materials without passing through gussets or other connecting parts;

5) The appearance is more beautiful, especially the pipe frame composed of steel pipes, without redundant node connections, which has a strong sense of modernity;

6) If necessary, pour concrete into the pipes to form composite members.

When the mechanical properties are stable, local buckling tends to occur when pressure is applied, but post-buckling strength and hydrodynamic resistance are most favorable. The minimum force is poor. Under the same cross-sectional area, the surface area is the smallest and slightly larger; more materials are used for refractory and anti-corrosion materials.