Weld Repair of 310S Stainless Steel Pipe Crack

310S is a heat-resistant stainless steel, with good oxidation resistance, corrosion resistance, widely used in ion-exchange membrane electrolysis of the alkaline pipeline. As the material process requirements are high, once the base metal and filler material alloying elements are not complete, improper welding process, working condition is not good, pipe corrosion, work stress and other reasons will cause serious defects in pipeline cracks, will bring to the production A serious risk. So, the welding of the crack repair has become an important maintenance method.

First, the crack for direct welding (mainly used for ≤ φ89 pipe cracks)
1, do the preparatory work before welding, from the two ends of the crack at the end of each 10mm drill φ6mm crack hole, has prevented the grinding process of welding crack propagation. And then use the angle grinder grinding groove angle α = 60 °, gap b = 3.2mm, blunt edge p = 1.5mm groove. The length of the groove is the distance between the cut holes, and through the hole grinding out the weld and the base metal transition surface, and the groove on both sides of the oil, rust and other debris clean up.
2, the use of ZX7-400A welder, DC reverse, welding consumables A402, φ3.2mm for rendering, filling and cover, welding current of 110A.
3, the use of arc welding primer, even with arc welding and cover, and single-channel primer, double-channel filling, 3-channel cover. Everything is thoroughly cleaned, each connector should be staggered around 15mm, to ensure that no defects. Welding direction from left to right, the order of welding for the layer by layer from bottom to top.
4, after welding, the appearance of the weld to be flat and weld height h ≤ 1mm, width ≤ 4mm, done by color inspection qualified to use after normal use.

Second, dig repair repair (mainly used for ≥ φ89 pipe cracks)
Dumping repair is the pipe has been the site of the crack, with a plasma arc to completely cut off, and dig out the width of 150mm, than the two ends of the visible cracks at the end of 20mm pipe base material. And then according to the size of the excavated base material to choose the same axis with the material patch block, the repair site for welding repair.
1, grinding and group pairs In order to avoid stress concentration, so that welding seam smooth transition, you must first dig holes and patches of the edge of the cut off 1mm, and then the four corners polished into a circular arc, and finally repair the V-shaped Groove, and the groove on both sides of oil, rust and other impurities clean up. Recommended groove size: bevel angle α = 60 °, reserved gap b = 3.2-4.0mm, blunt edge p = 1.5-2.0mm. Welding to strictly control the gap size, and to be basically the same.
2, welding equipment and methods of welding machine using ZX7-400A or other inverter DC, silicon rectifier welder, are DC reverse, so that the welding process arc stability, splash small, so as to further ensure the quality of welding. Welding using argon arc welding base, to prevent the electrode arc welding electric residue in the pipeline caused by damage to the equipment. Using A402φ3.2mm electrode welding arc welding, cover. Welding current control in the 85-105A, and each arc after cooling 3-4S and then arc, the electrode swing the smaller the better.