According to ASME B30.26, the screw pin of the shackle shall be?

• A. Partially engaged
• B. Fully engaged
• C. Loose
• D. Interlocked

Answer: (B)

Screw pin shackles must stay secure under load, so the screw pin should be fully engaged. When the pin is fully screwed in and tightened, the pin is locked into the shackle body and the load path remains stable; this prevents the pin from spinning or backing out as the shackle experiences dynamic forces, vibration, or bending. A fully engaged pin ensures the load is carried through the correct surfaces and that the connection cannot inadvertently open, which is essential for preventing drops or misalignment.

If the pin were only partially engaged, or left loose, loads could cause the pin to loosen or back out, compromising the integrity of the connection. An interlock or other locking mechanism isn’t a substitute for proper engagement of the screw pin in this context, so those conditions do not meet the requirement.