Client Requirements
A regional wastewater authority needed a 100-foot 304L stainless trough to replace a failed unit during a scheduled plant outage. The specification was simple but unforgiving: straightness held within 1/8 inch end-to-end over the full 100-foot run. An earlier vendor had attempted the job and couldn’t hold tolerance across the span, which is what brought the work to Northern.
Northern’s Approach
Distortion on a 100-foot stainless weldment comes from heat input accumulating across the length. Our approach was to treat straightness as the primary engineering parameter, not an afterthought.
Sections were fit and laser-aligned before each weld pass. Welding followed our qualified 304L austenitic WPS, with controlled interpass temperatures and a deliberately moderated heat input to limit cumulative distortion. The work was jigged specifically for the 100-foot span, with alignment verified between passes rather than only after completion. Forming and fit-up were staged to let the assembly settle between critical operations.
Outcome
The trough delivered straight within 1/8 inch over 100 feet, tighter than the specified tolerance. Installation went in without field rework or shimming. The trough has been in continuous service since.
