Check welds and joints
Look at every weld point: consistent, cleanly finished joints with no visible porosity, cracks or rough grinding marks. Welds are where quality differences show most clearly (and where passivation matters most).
Check finish consistency
On brushed finishes, the grain direction should run consistently across matching components — mismatched grain direction on adjacent pieces is a visible quality lapse. On mirror finishes, check for swirl marks or dull patches under good light.
Check stability and fit
Push firmly on railings at several points — there should be no flex or movement at the base fixings. Check that gaps are even and that spacing meets the safety norms specified.
Check against your original spec
Grade, finish, dimensions and quantity should match what's on your quotation — this is the last convenient moment to reconcile any differences.
Raise issues then, not weeks later
A fabricator can usually fix a finish or fitting issue easily while the team and equipment are still on-site. The same fix weeks later means a return visit — harder for everyone, and a common source of avoidable friction. Also confirm what your warranty covers at this point.