Northern Manufacturing trial fits and function tests fabricated assemblies before they ship from our Oak Harbor, Ohio facility. Mating sections are assembled on up to 160,000 sq ft of indoor floor, dimensions are verified against your CAD model with a Leica Absolute Tracker AT960 and AS1-XL scanner, moving parts are exercised, and tanks get hydrostatic and leak testing. The economics are blunt: a fit-up issue caught here costs hours in the shop; the same issue at your site costs days in the field with a crew and crane on the clock.
The verification is run by the same quality organization that stands behind our fabrication: ISO 9001:2015 certified by AVU Registrations (IAS-accredited, certificate #00157-4), an AWS Certified Welding Inspector on staff, and ASNT SNT-TC-1A Level III NDE capability in-house. When a regional wastewater authority needed a 100-foot trough straight within 1/8 inch, this is the discipline that proved it before the truck was loaded.
What a Trial Fit Verifies
A trial fit answers the question individual part inspection cannot: does the system go together? We assemble mating components, large multi-section weldments, and complete systems in our bays and physically prove:
- Critical interfaces. Flange faces, mounting surfaces, and mating sections engaged the way installation will engage them
- Hole patterns. Bolted connections proven with hardware, not overlaid drawings
- Clearances. Moving parts swung through their travel, access envelopes confirmed
- Overall dimensional accuracy. The assembled geometry measured against the model, where tolerance stack-up across joints either passes or fails
Sections are match-marked as they are proven, so the exact fit demonstrated on our floor is the fit your field crew reassembles. Our power generation ductwork work ran every assembly through a factory dry fit against its mating section before release, with no “we’ll adjust it in the field” allowances.
Dimensional Verification Against the Model
Verification methods scale with the size and criticality of the assembly. The drawing and your spec set the scope; the table below is how the methods divide the work.
| Method | Equipment | What it proves |
|---|---|---|
| Laser tracker measurement | Leica AT960 + AS1-XL scanner | Large-volume geometry measured directly against the CAD model |
| Model-based inspection | Native 3D CAD comparison | Dimensions and GD&T validated against the model, not a 2D dim chain |
| Layout projection | FARO laser projectors | CAD outlines projected on the work to confirm component placement |
| Weld geometry scanning | Servo-Robot WiKi-Scan | Fillet size, leg length, throat, and undercut captured quantitatively |
| Material confirmation | Handheld XRF PMI analyzers | Alloy verified on specialty-grade components |
Weldment tolerances reference ISO 13920 unless your spec calls tighter, and the output is a quantitative report, archivable and auditable, rather than an inspector’s initials next to a checkbox.
Functional Testing: Exercise It Here, Not On Site
Static fit is half the answer. For dynamic assemblies, we test the mechanics before shipment:
- Range of motion verified on rotating and articulating elements through their full travel
- Motors and pneumatic systems that we mechanically integrated are exercised to confirm the drivetrain and actuation behave as designed
- Hydrostatic and leak testing on tanks and welded containment, with vacuum box testing on seams where the method applies
- Weld verification by dye penetrant testing and ferrite measurement on duplex welds, per the drawing
Electrical integration and controls commissioning stay with you or your integrator; our scope is the mechanical proof that the hardware they energize is right.
Witness Points and Third-Party Inspection
Customer witness and hold points are written into the inspection plan during quote review, and we host your inspector or third-party inspection agency on our floor for them. TPI is typically arranged and contracted by the customer. Flag the hold points when the order is placed so they are planned into the work rather than bolted onto it.
What Ships With a Verified Assembly
- Dimensional verification report against your CAD model, including laser tracker data when specified
- Trial fit records and photographs of the assembled, match-marked system
- Functional, hydrostatic, and leak test records for the tests in scope
- NDE reports (PT and others as specified), with ferrite measurements on duplex welds
- Match-mark documentation so field assembly repeats the proven fit
- Certificate of Conformance to your purchase order
Trial fit and functional testing run as the final gate on work we fabricated and assembled, or as a defined verification step your spec calls out. Either way, the assembly that leaves Oak Harbor has already been built once.
