Bolts

Hex bolts and hex cap screws come in a variety of styles to meet many different application needs. They are available in many standard grades and property classes, with various finishes and markings. The type of steel and the treatment of the material during manufacture determine their strength and performance capabilities. Tensile strength and yield strength are the major factors in classifying bolt grades and types. Bolts conform to SAE (Society of Automotive Engineers) standard J429, various ASTM (American Society for Testing and Materials) standards, and ISO (International Organization for Standardization) standards. Examples of SAE J429 standards include Grade 2, Grade 5, and Grade 8. Examples of ASTM Standards are A307 Grade A (A307A) and A325 Type 1. Examples of ISO standards include property classes 8.8 and 10.9. The grades, types, and classes are designated by markings on the bolt head. The diameter of a bolt is determined by measuring the shank's diameter. The length of a bolt is measured from the end of the threads to the underside of the hex head. The head size is ascertained by measuring across the flats of the hexagonal head. The head size determines the wrench or socket size needed for tightening. Hex bolts and hex cap screws come in various finishes, including plain finish, zinc plated, yellow zinc plated, and hot-dipped galvanized, which are the most common. Be sure to match the grade and finish of your bolt with the nut for proper assembly.