Why is a proper torqueing sequence critical for a bolted flange assembly?

• A. To shorten maintenance time.
• B. To ensure even preload, avoid leaks, and prevent distortion or structural damage.
• C. To reduce heat generation.
• D. To allow using fewer fasteners.

Answer: (B)

A proper torqueing sequence ensures even clamp load around the flange. By tightening bolts in a cross-pattern or as specified, each bolt stretches similarly, pulling the flange faces together uniformly. That even preload seats the gasket evenly, maintains a tight, leak-free seal, and prevents distortion or local overloading that could crack the flange or bolts under pressure and temperature changes. Without the correct sequence, some bolts may carry more load than others, leading to leaks or structural damage. The goal of sequencing is reliable sealing and structural integrity, not merely reducing time, reducing heat, or using fewer fasteners.