Question

A 4" thick 5 Chrome vessel operates at 1200 psig and 900°F. When is this vessel least likely to fail by Brittle Fracture?

A) hydrotesting
B) Normal Operation
C) shutting down the unit
D) starting up the unit

Answer 1

A 5 Chrome vessel operating at 1200 psig and 900°F is least likely to fail by Brittle Fracture during Normal Operation. Brittle Fracture is more likely during rapid temperature changes, as during startup and shutdown. Hydrotesting involves high pressure at lower temperatures and in a controlled environment.

Step-by-step explanation:

The vessel described is least likely to fail by Brittle Fracture during Normal Operation, as the operating conditions are steady and the material properties are stable at the working temperature and pressure. Brittle Fracture is more likely during situations where thermal stresses are introduced, such as rapid temperature changes, which can occur during startup and shutdown processes. Hydrotesting, while involving high pressure, is done at lower temperatures and in a controlled manner to ensure material integrity without causing failure. Therefore, absent of any stress concentrators or material deficiencies, the vessel under normal operating conditions is less susceptible to brittle fracture compared to other listed scenarios.