Fasteners · ASME B18.2.1 · DIN 931 / 933
Hex Bolt — ASME B18.2.1
Hex bolt — a bolt with a hexagonal head. Hex bolts join flanges, structures and equipment where one side is accessible for the head. Dimensions to ASME B18.2.1 or DIN 931 / 933.
- ASME B18.2.1
- 18 grades
- EN 10204 3.1 / 3.2
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
Hex Bolt: What to Know Before Ordering
- Partially or fully threaded
- ASME B18.2.1 / DIN 931 / DIN 933
- Supplied with nuts and washers
Hex Bolt Materials & Grades
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 hex bolt | ASTM B425 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L hex bolt | ASTM B649 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 hex bolt | ASTM A193 B8 · A194 8 | General corrosion resistance, food, water and architectural work |
| SS 304L hex bolt | ASTM A193 B8 · A194 8 | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S hex bolt | ASTM A276 / A479 | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L hex bolt | ASTM A193 B8M · A194 8M | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 hex bolt | ASTM A193 B8T | High-temperature service between 425 and 815 °C |
| SS 347 hex bolt | ASTM A193 B8C | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 hex bolt | ASTM A276 / A479 | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 hex bolt | ASTM A276 / A479 | Seawater and high-chloride service where strength also matters |
| Inconel 600 hex bolt | ASTM B166 | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 hex bolt | ASTM B446 | Seawater, high strength and high temperature in one alloy |
| Inconel 718 hex bolt | ASTM B637 | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT hex bolt | ASTM B408 | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 hex bolt | ASTM B574 | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 hex bolt | ASTM B574 | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 hex bolt | ASTM B164 | Seawater, hydrofluoric acid and marine service |
| Monel K500 hex bolt | ASTM B865 | High-strength pump shafts, bolting and springs in seawater |
Other fasteners
Stud boltA fully threaded rod supplied with two heavy hex nuts.Heavy hex nutA thicker and wider hexagon nut for pressure bolting.Hex nutA standard hexagon nut.WasherA flat or spring ring that spreads bolt load.Threaded rodA continuously threaded bar cut to length.U-boltA U-shaped bolt for clamping pipes to supports.Eye boltA bolt with a loop head for lifting or anchoring.Anchor boltA bolt that fixes structures or equipment to concrete.Foundation boltA heavy bolt set in concrete for machinery bases.Socket head cap screwA screw with a cylindrical head and hexagon socket.Machine screwA small-diameter screw for equipment assembly.
Hex bolt — questions buyers ask
DIN 931 or DIN 933?
DIN 931 bolts are partly threaded; DIN 933 are fully threaded.
Which grades are hex bolts available in?
Inconel 825, SS 904L, SS 304, SS 304L, SS 310 / 310S, SS 316 / 316L, SS 321, SS 347, Duplex 2205, Super Duplex 2507, Inconel 600, Inconel 625, Inconel 718, Incoloy 800 / 800H / 800HT, Hastelloy C276, Hastelloy C22, Monel 400, Monel K500.
Which standard covers hex bolt dimensions?
ASME B18.2.1 · DIN 931 / 933. The material standard depends on the grade.
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