Quality assurance, technical evaluation and continuous improvement
QA versus QC
Quality assurance is the system that makes quality predictable - documented procedures, competence, calibrated equipment, controlled drawings and specifications. Quality control is the inspection and test that proves it on the day. Candidates should be able to distinguish the two and describe an inspection and test plan (ITP) with hold points (work cannot proceed) and witness points (the client may attend but work can continue).
Non-conformity and corrective action
A non-conformance report records what is wrong, the immediate containment, the root cause, the corrective action and the verification that it worked. Root-cause tools include 5 Whys and the fishbone (cause-and-effect) diagram. The trap is to record a non-conformance and stop at rework - without addressing the cause it will recur.
Technical evaluation and improvement
Evaluate tenders and designs against the specification rather than the headline price: energy performance, whole-life cost, refrigerant GWP, serviceability, spares, warranty and compliance evidence. Use audits, KPIs, energy monitoring, client feedback and lessons-learned reviews to drive improvement within a plan–do–check–act cycle, and manage documents and revisions so the site always builds the current version.
Worked example
Three leak failures on the same plant in a year. Ask why five times: leaks at flare joints → joints not torqued to spec → no torque wrench on the van → tool not on the standard kit list → kit list never reviewed. The corrective action is a revised kit list and a briefing, not a fourth repair.
Traps
Confusing hold and witness points; treating an audit as a fault-finding exercise rather than improvement; accepting the lowest price without technical evaluation.