Piping Materials Engineering & Selection

A: A: Sounds reasonable under COMAH pressure, but HSE audits against legal compliance and contract control, not retroactive upgrades. B: The contract reference locks the edition; changing editions without MOC is a breach you can’t defend. C: Mixing clauses across editions breaks code intent and traceability; auditors hate hybrids. D: Specs don’t override unless the contract hierarchy says so, and you’d need that clause in writing.

A: A: That’s the pressure term only; CA hasn’t been added and the diameter basis is muddled. B: CA is never buried in allowable stress; dropping it is a classic late-project mistake. C: Pressure term lands near 8.5 mm, then +3 mm CA puts you in the low‑11s before tolerance. D: OD vs ID shifts the number, but not enough to land here once CA is included.

A: A: There’s no wall thinning or oxide; FAC doesn’t act this fast on dry gas. B: Noise, small-bore branch, rapid crack growth — that pattern lines up cleanly. C: Thermal cycles here are too slow and low-amplitude for a 3‑month failure. D: Residual stress alone doesn’t explain the vibration sensitivity or noise reports.

A: A: Scaling linearly from DN100 ignores area growth; it’s too light. B: OD ~219 mm, wall ~8 mm gives the right steel volume when you sanity-check it. C: That treats it like a solid bar; nobody’s installing that. D: Fabrication factors don’t change physical weight; they’re for cost and schedule.