The Basics of Field Welding Repair on Construction Equipment
Print Article
Learn about the essential steps to field repair: Cutting and removal, preparation of the new joint/part, and welding and cleanup.
In the construction industry, nothing cripples a jobsite like a broken machine. When it comes to fixing broken steel in the field, there are three steps to master:
* Cutting and removal of the failed component.
* Preparation of the new joint/part.
* Welding and cleanup.
This article discusses these three stages and helps guide you to the right combination of equipment to meet your field repair needs.
 |
Stick welding, or SMAW, is the most commonly used process for field repair |
Cutting and Removal of the Failed Metal
The first step in welding repair is removal of the damaged metal. This can be done with oxy-fuel, plasma cutting or carbon arc gouging. Oxy-fuel and plasma are typically better for cutting through metal, whereas carbon arc gouging is better for gouging out a crack or defect without completely severing the part.
Oxy-fuel torches are one of the most common tools for cutting and are found on most service trucks. Plasma cutters, however, produce a smaller kerf (cut width), a smaller heat affected zone (HAZ), and are typically faster than oxy-fu
el torches. Plasma cutters also cut through all electrically-conductive metals, whereas oxy-fuel won’t cut through aluminum or stainless steel.
Carbon arc gouging is another option when using welding generators with 250 to 500 amps of output and a high duty cycle. This process uses a carbon electrode to melt the defective area, and blast away molten metal with a focused, high-pressure stream of air.
To begin: cut away the damaged area and remove all rough edges to ensure proper fit-up of the replacement part. It is extremely important to fully grind out all cracks—even beyond what’s visible—because the slightest remnant of a defect will continue cracking even after a weld is laid over it.
 |
Engine-driven welding generators feature 5,500 to 20,000 watts of generator power , depending on the model, for running grinders (pictured), drills and other tools. |