GB/T 31.3-2025 in English

This standard specifies the technical requirements for a specific type of fastener, namely hex head screws with holes, focusing on the third part related to fine pitch threads. It outlines the dimensional specifications, material properties, and testing methods necessary to ensure compatibility and performance in various applications. The standard also includes guidelines for marking and packaging, ensuring consistency across manufacturing processes. It provides detailed information on thread dimensions, tolerances, and mechanical properties to facilitate proper design and use. Additionally, it addresses the requirements for inspection and acceptance criteria to guarantee product quality. The document serves as a reference for manufacturers, designers, and users in the industry.