Alloy steel pipe welding precautions

2018-03-11

1. After the preheating temperature isreached, the welding of the bottom bead is carried out immediately, and thewelding should be carried out once. The bottom bead is required to be weldedand formed well, and the height of the bottom bead of the wall thickness pipeis not less than 3 mm.

2, the preheating range of the alloy steelpipe nozzle before welding should be based on the centerline of thecounterpart, each side is not less than three times the wall thickness, and notless than 100 mm, the heating temperature should be 200 degrees heating shouldbe uniform, to prevent local overheating heating Heating, oxygen-acetyleneheating can be used without conditions.

3. After the completion of the bottom bead,the welding of the surface bead should be carried out immediately, and eachweld should be continuously welded once at a preheating temperature of 200 °C.If the welding is interrupted, the post-heat should be taken (300 °C). , 30minutes), slow cooling (insulation material) and other measures, should beinspected before welding, confirm that there is no crack before theconstruction according to the original process requirements; multi-layerwelding room temperature should be equal to or slightly higher than the preheatingtemperature, each layer The joint of the electrode should be staggered. If thewelding is completed, if it can not be immediately heat treated, it should beimmediately 300 ° C. After 30 minutes, heat treatment and then tied withinsulation material to slow down. During the welding process, the nozzle shouldbe closed to prevent the wind from entering the hall. With wind and rainmeasures.

4. The appearance of the weld should beneat and beautiful, and there are no defects such as pores, slag inclusions andcracks on the surface. Welds are allowed to have undercuts with a depth of lessthan 0.5 mm (except as otherwise specified) but the cumulative length is notgreater than the total length of the weld.

5. After all the butt welds have beenwelded, the welder applies the appropriate method to mark the stamp number onthe side of the weld, and the visual inspection by the construction teamquality inspector. The 100% inspection pipeline also records the inspectiondata in the inspection record of the weld.