Hex Head Bolts
Flange Bolts, Hex Cap Screws and Tap Bolts
Though these fasteners go by many names, including hex bolts, flange bolts and hex screws, the characteristic that they all share is a hexagonal head, designed to be driven by a wrench. They all are commonly referred to as both bolts and screws. Hex Cap Screws are unique because of the threading. Hex Cap Screws are partially threaded with a shoulder beneath the head. Tap Bolts are fully threaded up to the hexagonal head. The unique characteristic of Flange Bolts is the design of the head, from which they get their name. The "flange" of the bolt is a built in (integral) washer. In Imperial sizes, this washer is serrated to act as a lock washer.
18-8 Stainless Steel
A hex cap screw is a cap screw with a hexagonal head, designed to be driven by a wrench (spanner). An ASME B18.2.1 compliant cap screw has somewhat tighter tolerances than a hex bolt for the head height and the shank length. The nature of the tolerance difference allows an ASME B18.2.1 hex cap screw to always fit where a hex bolt is installed but a hex bolt could be slightly too large to be used where a hex cap screw is designed in.
316 Stainless Steel
316 stainless steel provides the strongest corrosion resistance and is non magnetic. Hex cap screws and tap bolts in 316 Stainless Steel are used for salt water and water treatment applications, food processing prep area equipment. Used on boats, docks, oil gas refining plants for direct use in salt water. Compliance with ASTM and certification available upon request.
A2 Stainless Steel
Comparable to 18-8 Stainless Steel, A2 Stainless Steel is the standard for Metric sized fasteners. Metric hex cap screws are corrosion-resistant. A hex cap screw is a cap screw with a hexagonal head, designed to be driven by a wrench. A DIN 930-933/ISO 4014-4017 compliant cap screw has somewhat tighter tolerances than a hex bolt for the head.
Alloy Steel is the most common material that fasteners are manufactured in. Alloy steel fasteners are often treated, coated or plated with zinc for additional corrosion resistance. Alloy steel is used for the hot dipped galvanized process, treated in a molten zinc bath which creates a tightly bonded alloy finish. Alloy steel is most often available in Grade A, Grade C, Grade 2, Grade 5 and Grade 8. Untreated alloy steel fasteners are black. Hex Head Bolts in untreated Alloy steel are often referred to as a plain finish. Treated alloy steel hex bolts are often referred to as the grade and zinc.
Hot Dipped Galvanized Steel
Hot dip galvanizing is a process that adds a layer of corrosion resistance by dipping fabricated steel into a kettle containing molten zinc. The HDG process creates a tightly bonded alloy for superior corrosion resistance and harsh environment applications. HDG products must be used exclusively when applied, meaning that a plain zinc nut or stainless nut cannot be applied to a Hot Dip Galvanized Hex Bolt.
Silicon bronze fasteners are made of copper, silicon, and various other alloys such as zinc, tin, iron and manganese. Silicon bronze is used in marine environments, corrosive environments, and high heat environments. Often used in plumbing and electrical applications, silicon bronze fasteners are also found on tattoo machines and in power plants.