The type of failure mode that likely to occur due to mechanical and metallurgical deterioration

Mechanical and metallurgical deterioration encompasses damage mechanisms that degrade the material's inherent properties, such as toughness and ductility. Mechanisms like brittle fracture, temper embrittlement, and high-temperature creep reduce a material's ability to deform safely under stress. This often leads to a sudden, rapid, and extensive failure without prior warning (e.g., leak-before-break). Therefore, the most likely failure mode is a catastrophic rupture, representing a complete and sudden loss of integrity.

A. Small holes to ruptures: This progression is more typical of thinning or widespread pitting, not brittle failure mechanisms.
B. Cracks: While cracking is a precursor, "catastrophic rupture" better describes the ultimate failure mode for these mechanisms.
D. Leaks: These mechanisms typically do not exhibit leak-before-break behavior; failure is sudden and complete.

1. API Recommended Practice 580, Risk-Based Inspection, 3rd Edition, 2016, Section B.2.3.1 (Brittle Fracture): "The failure mode is a sudden catastrophic fracture at a stress below the yield strength of the material."

2. API Recommended Practice 580, Risk-Based Inspection, 3rd Edition, 2016, Section B.2.3.5 (Temper Embrittlement): "The primary concern with temper embrittlement is the potential for a catastrophic brittle fracture..."