In the production of welded steel pipe, the groove of the tube is the shape of the cross-section, the general manufacturers in the slitting directly into the high-frequency welding, the groove is a "I" shape. When the thickness of the welding material is greater than 8 ~ 10mm above the pipe, if the use of this "I" shaped groove, because the relationship between the curved arc, you need to melt off the tube first contact with the inner layer, forming a high Burr, and easy to cause the center of the plate and the outer layer of insufficient heating, affecting the welding strength of high-frequency weld. Therefore, in the production of thick-walled tube, the tube is best through the planing or milling edge treatment, so that the groove was "X" shape, the practice proved that this groove for the uniform heating to ensure the quality of the weld seam of welded steel pipe has a great relationship. The selection of the groove shape also affects the size of the adjustment angle. The design of the welded joint is a weak link in the design of the welding project of welded steel pipe. It is not uncommon for the construction of many steel structures. The design of the groove is not from the hand of the welding engineering technician, the hard sleeve standard and the poor performance. The groove form plays an important role in controlling the internal quality of the weld and the quality of the welded structure. The groove design must test the fusion ratio of the base metal, the welding space, the welding position and the comprehensive economic benefits. The lateral shrinkage value ΔB should be calculated by the following equation.
ΔB = 5.1Aω / t + 1.27d
Where Aω - weld cross-sectional area, mm,
t - plate thickness, mm,
d - weld root gap, mm.
After finding the relationship between ΔB and Aω, we can analyze and process the data according to the relationship list, optimize the design, and finally determine the form of butt weld.