Nielsen is in his third year of a mechanical engineering apprenticeship at Page Macrae in Mount Maunganui and said he was looking forward to competing in Russia, along with travelling and enjoying the country's culture.
"I'm training really hard - on top of my 40-hour working week I'm spending every weekend and some evenings welding," he said.
"I went to America for a practice training round for welding, then Australia the week after for work, then across the Tasman again for another competition.
"Welding is filling up my passport."
He said the competition helped develop his knowledge of welding, especially on the technical side.
"I'm going to give it my best and try to win."
WorldSkills NZ has been running for more than 30 years and provides skill coaching to competitors.
WorldSkills NZ general manager for partnerships and innovation Ash Siddiqui said each competitor would face mental and time pressure and have to complete complex tasks in a completely new environment.
"They'll be totally out of their comfort zone," Siddiqui said.