What is the role of welding preheating for large-diameter seamless steel tubes

What is the role of welding preheating for large-diameter seamless steel tubes? The technical method of heating the entire large-diameter seamless steel tubes or the welding area before welding is called preheating. About large-diameter seamless steel tubes with high welding strength level, hardening tendency, exceptionally good thermal conductivity materials, large thickness weldments, and when the ambient temperature around the welding area is too low, before welding, it is usually necessary to preheat the weldment.

The primary intention of welding preheating for large-diameter seamless steel tubes is to reduce the cooling rate of the welded joints and the preheating temperature. When welding large-diameter seamless steel tubes with a tendency to harden, the primary technical method for decreasing the cooling rate and reducing the tendency to harden is to preheat, rather than increase the line energy.