Factors Affecting Preheat and Interpass Temperatures
Recommended location of the root pass in relation to the centerline of the cross section. X should be 5 mm smaller than Y/2.
When different steel types are welded together, the plates, sheets, round bars and tubes requiring the highest preheating temperature determines the required preheat and interpass temperatures.
The tables below are applicable for heat inputs of 1.7 kJ/mm (43.2 kJ/inch) or higher. If heat inputs of 1.0–1.69 kJ/mm (25.4–42.9 kJ/inch) are used, we recommend an increase of the temperature by 25°C (77°F) above the recommended preheating temperature. Furthermore, these preheating recommendations is valid for consumables recommended by SSAB with a max diffusible hydrogen content of 5 ml/100 g weld metal.
If a lower heat input than 1.0 kJ/mm (25.4 kJ/inch) is applied, we recommend that you use SSAB’s WeldCalc to calculate the recommended minimum preheating temperature.
If the ambient humidity is high or the temperature is below 5°C (41°F), the lowest recommended preheating temperatures given in the tables below should be increased by 25°C (77°F).
For plates thicker than 25 mm (0.984”), and joint geometries, where the root pass is close to the centerline of the plate such as double-V butt welds, we recommend locating the root pass approximately 5 mm (0.197”) away from the centerline of the plate, see illustrated above.
The information in this report is only applicable to SSAB’s products and should not be applied to any other products than original SSAB products.
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