Tolerances, Dimensional Inspection, and Documentation
What this domain tests
This domain tests dimensional verification, product tolerances, camber and sweep checks, and the records that prove conformance. Questions often distinguish product tolerances from erection tolerances and ask how to document a nonconforming dimension.
Core rules
- Project specifications and approved shop drawings govern dimensions and tolerances. PCI product tolerances and erection tolerances are not interchangeable.
- Inspect length, width, depth, squareness, strand projection, blockout position, cover, camber, and sweep at the required stage. Use calibrated tapes, levels, and gauges.
- Record actual readings, not just pass or fail. Identify the unit, drawing, inspection stage, inspector, date, and acceptance criterion.
- A dimension outside tolerance is a nonconformance. Document the measured value, evaluate structural and fit-up effects, and obtain a disposition before shipping.
- As-built records, repair records, and test reports must be retrievable and traceable to the unit.
Worked example
A 40 ft beam has a design camber of 1.0 in with a specified tolerance of plus or minus 0.5 in. Measured camber is 1.7 in. The deviation is 1.7 - 1.0 = 0.7 in, which exceeds the 0.5 in allowance by 0.2 in. The inspector records the reading and opens an NCR. Engineering evaluates bearing, clearance, and topping thickness; the disposition may accept the unit with documented review or require rework.
Traps
Using erection tolerance for a product check; recording only pass or fail; measuring camber at the wrong stage; and shipping a unit with an open dimensional NCR.