Knowledge
Technical fundamentals the job depends on
Knowledge questions probe whether you understand why the rules exist. Core areas: structural steel materials and their grades and toughness requirements; welding metallurgy basics such as heat input, preheat, and the effect of cooling rate; bolting including pretensioned and slip-critical connections and the meaning of turn-of-nut and tension-calibrated methods; dimensional tolerances for fabricated members; and coating systems including surface preparation standards and their effect on adhesion.
Understand the linkage between specification, procedure, and inspection: a toughness requirement drives consumable and preheat choices, which drive the welding procedure, which drives what the inspector verifies. Questions often test whether you can trace that chain rather than recall a single number.
Traps: memorizing tolerances without knowing whether they apply to shop or field conditions; confusing visual inspection with volumetric or surface NDT methods and what each can find; and assuming a coating will perform if surface preparation is skipped.
Rule of thumb: when a question asks what to do about an unfamiliar condition, the safe answer follows the chain - identify the requirement, follow the approved procedure, inspect to the plan, and document the result. Guessing at a number is usually the wrong path; applying the process is usually right.