ANSI B1.1 defines standards for which thread type?

• A. Unified inch screw threads
• B. Metric threads
• C. Gas threads
• D. Pipe threads

Answer: (A)

ANSI B1.1 sets the standards for unified inch screw threads—the form, size, and tolerances used on inch-based fasteners. This is the system that defines UNC and UNF thread forms, ensuring interchangeability of ordinary machine screws and related fasteners across manufacturers and applications in the inches world. Metric threads, by contrast, follow ISO metric standards, not B1.1. Pipe and gas threads are governed by other standards focused on piping and gas connections, not the general-purpose unified fastener threads. So the standard described by this code is the unified inch screw thread system.