No. U.S. days do not count toward that year. The qualifying full-time foreign employment and actual knowledge require separate evidence.
Keep the two factual questions distinct
Visits may explain experience while contributing no qualifying foreign days. Record what the person did and where, rather than treating all company time as foreign employment.
L-1B eligibility depends on specialized knowledge of the petitioning organization's own product, process, or procedures, and industry-standard welding certifications, however advanced, describe a skill set available broadly across the trade rather than knowledge tied to one employer. Qualifying specialized knowledge is either special knowledge about organizational products and services, research and equipment, techniques and management, or other interests—and how they apply in international markets—or an advanced level of knowledge about the organization’s processes and procedures. An assignment primarily at an unaffiliated worksite must not place the employee under the client’s principal control and supervision and must relate to a product or service requiring petitioner-specific specialized knowledge rather than labour for hire, and total L-1B stay is limited to five years.