Mechanical Design Engineer

A: Accepting the wider spacing relies on material strength and ignores bending amplification and fretting risk at the clamps. Increasing wall thickness shifts stress but drives weight and stiffness changes that break the original vibration substantiation. Reverting clamp spacing restores the qualified dynamic boundary conditions and keeps loads within the existing compliance envelope. Changing to Inconel alters mass, stiffness, and thermal growth enough to invalidate prior analyses and drawings.

A: Proof testing will screen out obvious defects and gross leaks before entry into service. It also demonstrates margin against one-time overpressure events near proof levels. Fatigue damage accumulates below proof stress and isn't exercised by a static test. Torque-related leaks are usually exposed during the proof or leak check itself.

A: CS‑25 doesn't assume ultimate loads are reached routinely in operation. Proof tests don't model long-term crack propagation under variable amplitude loads. Damage tolerance addresses the reality of small defects growing between inspections to failure. Corrosion control supports durability but doesn't replace crack growth assessment.

A: Lower operating pressure doesn't remove ovalization-driven stress concentration and flow disturbance. Vendor thinning limits don't capture in‑service vibration and fatigue effects. Meeting the established bend radius maintains known stress and fatigue allowables. Changing material temper affects allowables and corrosion behavior, expanding the certification impact.