ANSI Standard

The American National Standards Institute (ANSI) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international standards so that American products can be used worldwide.

Most industrial fasteners are covered by two basic standards: one for materials and properties; the other, for dimensions and tolerances. Specifications for materials and properties are published by the American Society for Testing and Materials (ASTM), although other groups such as the Society of Automotive Engineers (SAE) also publish specifications covering these requirements.

Standards for dimensions and tolerances are issued by the American National Standards Institute (ANSI) in cooperation with the American Society of Mechanical Engineers (ASME) and the Industrial Fasteners Institute (IFI). Where applicable, published specifications covering a particular fastener will be referenced in the section of this booklet dealing with that fastener.

Standard fasteners are basic industrial fasteners – square and hex bolts, cap screws, carriage bolts, lag screws, studs, nuts, rivets and others – which have been standardized over the years as to type‘, style, usage, properties, dimensions and tolerances. These include a vast range of sizes and types stocked by distributors and manufacturers for an almost limitless range of applications: the assembly and maintenance of vehicles, appliances, farm equipment, construction equipment, industrial and plant machinery of all kinds, furniture and toys.