Flange bolts are unacceptable if the bolt threads do not extend:

Flange bolts are unacceptable if the bolt threads do not extend:

• A. Outside the nut by more than 2 threads
• B. Inside the nut within 1 thread of the nut face
• C. If the bolts are not lubricated
• D. If the bolt length is too short

Answer: (B)

The important idea here is ensuring enough thread engagement inside the nut for flange bolts. When the threaded portion of the bolt is captured by the nut, you want it to extend close to the nut face—specifically within one thread of that face—so there is sufficient threaded contact to carry the load and develop the proper clamping force. If the threads inside the nut don’t reach near the nut face, engagement is too short, which can reduce the load‑carrying capacity, increase the risk of thread damage or loosening, and compromise the joint. Keeping the threaded portion inside the nut within one thread of the nut face ensures there’s enough engagement length to transfer load reliably. The other factors mentioned ( lubrication status or the bolt being too long) are separate considerations. Lubrication affects torque-tension behavior, and bolt length relates to overall fit, but they don’t define the required inside-nut engagement depth that this criterion specifies.

The important idea here is ensuring enough thread engagement inside the nut for flange bolts. When the threaded portion of the bolt is captured by the nut, you want it to extend close to the nut face—specifically within one thread of that face—so there is sufficient threaded contact to carry the load and develop the proper clamping force.

If the threads inside the nut don’t reach near the nut face, engagement is too short, which can reduce the load‑carrying capacity, increase the risk of thread damage or loosening, and compromise the joint. Keeping the threaded portion inside the nut within one thread of the nut face ensures there’s enough engagement length to transfer load reliably.

The other factors mentioned ( lubrication status or the bolt being too long) are separate considerations. Lubrication affects torque-tension behavior, and bolt length relates to overall fit, but they don’t define the required inside-nut engagement depth that this criterion specifies.