When the original spec was unbuildable

Client Requirements

A regional power generation facility needed replacement exhaust ductwork with large-diameter sections that had to mate perfectly to existing in-plant flanges during a scheduled outage. Field labor was the expensive constraint: every hour spent forcing alignment on site drove six-figure impact.

Northern’s Approach

Sheet stock was CNC laser cut to programmed flat patterns, rolled to diameter on our heavy-gauge cylinder roller, then seam-welded using a mix of robotic GTAW for the long longitudinal passes and manual GTAW for tie-ins and branch fittings. Before release, every assembly was fit up dry on the shop floor against its mating section to verify alignment to our inspection drawings. No “we’ll adjust in the field” allowances.

Outcome

Field crews installed the duct run without rework, with sections dropping into position on the first attempt. The facility’s project manager credited the factory dry-fit as the difference between a clean outage and a prolonged one.

From the floor

Heavy-gauge stainless duct section with stiffening bands Full-envelope module staged under the overhead cranes Panel welding on the fixture table Large stainless weldment under the shop cranes