Weld repair guide covering crack repair procedures, metal buildup, hardfacing, and in-service repair techniques. Proper joint preparation, filler selection, and procedures for structural and equipment repair.
Repair welding is a different discipline from production welding. You’re working on unknown base metals, in awkward positions, on parts that have been heat-cycled, work-hardened, or contaminated with oil and grease. The procedures are more demanding because you’re restoring structural integrity to something that already failed once.
Identify the base metal first. This is the step most people skip, and it causes more repair failures than anything else. A spark test, grind test, or magnet check narrows down the alloy family. Mild steel, cast iron, high-strength steel, and stainless all require different filler metals and procedures. Welding a high-carbon steel part with E6013 instead of a low-hydrogen rod guarantees another crack.
Remove the defect completely. Grinding out a crack to what looks like sound metal isn’t enough. Use dye penetrant inspection (DPI) to confirm the crack is fully removed before welding. A crack that’s 2 inches on the surface is often 4 inches below.
Crack repair is the most frequent job. Drill stop holes at crack tips, grind a V-groove to sound metal, verify with DPI, and re-weld. Preheat high-carbon and alloy steels per the material requirements to prevent hydrogen cracking in the heat-affected zone.
Buildup and restoration adds material to worn shafts, bearing journals, and mating surfaces. Use a compatible filler and keep heat input low to minimize distortion. Machine or grind back to final dimensions after welding.
Hardfacing deposits wear-resistant alloy on surfaces subject to abrasion, impact, or erosion. Bucket edges, auger flights, crusher components, and tillage tools all benefit from hardfacing. Apply in stringer beads, not weave patterns, for best wear properties.
In-service repair means welding on equipment that can’t be taken out of production. This requires hot-work permits, fire watches, and often specialized procedures for welding on vessels or piping that may contain residual product.
For filler metal selection by application, visit our welding consumables section. Back to welding applications for more guides.
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