Which fastener is an exception to the requirement for material grade marking?

• A. Hex bolts
• B. Wood screws
• C. Machine screws
• D. Socket-head cap screws

Answer: (D)

Grading marks on fasteners tell you the strength and material properties you’re getting, so you can match the fastener to the load it must carry and the environment it’ll operate in. Most standard fasteners have a grade mark on the head so you can quickly verify its capability. Hex bolts and machine screws are commonly marked this way, giving you a visible indication of their strength class.

Socket-head cap screws are the exception because, in many standards, the strength or grade isn’t stamped on the head. The required grade for these fasteners is usually conveyed by the product specification or the accompanying documentation rather than a head stamp. When you work with them, you rely on the supplier’s data sheet or part number to confirm the strength class rather than reading a mark on the head itself.

So, while many fasteners show their grade directly, socket-head cap screws often do not have a material grade marking on the head, making them the exception.