What is the minimum high-strength bolt extension required after installation?

The correct answer is that the minimum high-strength bolt extension required after installation should be flush with the outer face of the nut. This requirement ensures that the bolt is properly engaged with the nut to maintain the necessary clamping force and structural integrity of the connection.

When the bolt is flush with the nut, it indicates that the bolt has been sufficiently tightened to fully seat within the nut, helping to prevent any movement or loosening over time. This condition is critical in high-strength bolting applications where the joint must maintain tightness under various loads and environmental conditions.

In contrast, if a bolt protrudes slightly or is visible by at least one thread, it may indicate that the bolt has not been properly tightened or seated. This could compromise the performance of the connection and result in potential failure under load. Additionally, a bolt that is long enough to accommodate a washer does not address the critical aspect of ensuring the bolt extends flush with the nut, as the presence of a washer does not determine correct tightening or bolt engagement.