Which statement describes the use of square threads?

• A. They are used in high-load applications.
• B. They are used for pipe sealing.
• C. They have a 29-degree angle.
• D. They are decorative.

Answer: (A)

Square threads are chosen for mechanisms that must transmit large axial forces with a straightforward, low-wedge drive. Their squared, flat flank provides a strong, direct contact between the screw and nut, so the load is carried efficiently along the thread line. This makes them ideal in high-load applications like leadscrews in machine tools, jacks, and other linear actuators where precision and strength are important. They’re not used for pipe sealing, which relies on tapered or different thread forms to create a seal, nor do they feature a 29-degree thread angle (that angle belongs to Acme threads, not square), and they aren’t decorative.