Quality control verifies products meet specifications through inspection, testing, and documentation, ensuring fabricated equipment conforms to requirements and codes. QC encompasses incoming material inspection, in-process verification during fabrication, non-destructive examination of welds, dimensional inspection confirming geometry, pressure testing validating integrity, and final inspection before shipment. Effective QC catches defects when correction is least expensive and prevents nonconforming products from reaching customers.

QC systems require documented procedures, qualified inspectors, calibrated equipment, objective evidence through records, and corrective action processes. For ASME code fabrication, third-party authorized inspectors provide independent verification. Quality control differs from quality assurance—QC verifies product conformance while QA encompasses management systems preventing defects. Both are essential: QA prevents problems; QC detects those escaping prevention. Quality culture supporting QC includes management commitment, inspector authority, systematic problem resolution, and continuous improvement.