When working for Silico Products, Naddir Patel noticed that despite the SAW process being highly efficient in depositing weld metal, some of his customers were experiencing significant downtime between processes. They also were getting burn-through defects because welders were not proactively measuring the inter-pass temperatures.

Selecting a different high-deposition power source, such as twin wire, tandem wire, or power wave source was not a viable option simply from a capital cost standpoint. Retraining welders and requalifying weld procedures also would increase a project’s capital cost. This high capital investment still would have limited versatility in a typical multitasking shop that makes circumferential welds on 6-in. to 42- in. diameters in various plate thicknesses.

A published survey indicated that increasing electrode extension would seem to be the ideal remedy for increasing production rates and decreasing the heat input.

Whereas earlier attempts to increase electrode stickout (extension) were not very successful or consistent, Patel found a company that produced ceramic nozzles that could be screwed onto the contact tip of the welding head to guide the hot wire without jamming it.

This simple ceramic nozzle allows electrode extensions of 3 in. or more without wire straying. It eliminated arc wandering, provided adequate weld penetration, and produced quality welds. As welding parameters were not changed (except for a very small voltage increase), there was no need to requalify weld procedures.

The electrode extension was increased in increments to yield deposition rate improvements of 45 percent without any radiographic testing (RT) defects occurring.

As the heat-affected zone (HAZ) was narrower, narrower grooves were designed for greater efficiencies and less distortion.

Tests found that a 3/32-in. electrode with a 2 ¼-in. extension could be used for normal welds on various material thicknesses. Heavy-walled welds were completed with a 5/32-in. dia. electrode.

Tests were conducted at various customer locations and on a variety of groove welding applications for both mild steel and stainless steel in a 350- to 650-amp range.

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Tags: types of welders, Welders, welding, welding equipment, welding safety