Quality Assurance, Testing and Inspection
QA Versus QC
Quality assurance is process-oriented and preventive: procedures, training, audits, and documented systems designed to prevent defects. Quality control is product-oriented and detective: testing, inspection, and measurement of the output. Confusing the two is a classic exam trap-QA builds confidence in the process, QC verifies the product.
Inspection and Test Plans
An Inspection and Test Plan (ITP) lists hold points (work cannot proceed without sign-off), witness points (notify and allow observation), and review points (documents submitted for record). Sampling plans, calibration of instruments, and traceability of test results are essential. A test performed with an out-of-calibration instrument is not evidence.
Non-Conformance
When work fails a test, raise a non-conformance report (NCR): describe the deviation, contain it, determine disposition (rework, repair, use-as-is with engineering approval, or reject), and verify closure. Root-cause analysis prevents recurrence.
Traps
Questions slip in "QA inspected the weld"-inspection is QC. Another trap: assuming a failed test can be averaged with passing results, or that a hold point can be released verbally without documentation.
Rule of Thumb
QA prevents; QC detects. Worked example: a concrete cylinder fails its 28-day strength test. The technologist raises an NCR, quarantines the affected pour, arranges core testing, and refers the disposition decision to the engineer of record-rather than retesting until a passing result appears.