Fasteners · ASME B18.2.2
Heavy Hex Nut — ASME B18.2.2
Heavy hex nut — a thicker and wider hexagon nut for pressure bolting. Heavy hex nuts go with stud bolts on flanges. They spread load better and resist thread stripping at high preload. Made to ASME B18.2.2.
- ASME B18.2.2
- 18 grades
- EN 10204 3.1 / 3.2
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
Heavy Hex Nut: What to Know Before Ordering
- Thicker than standard hex nuts
- ASME B18.2.2
- Paired with A193 studs
Heavy Hex Nut Materials & Grades
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 heavy hex nut | ASTM B425 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L heavy hex nut | ASTM B649 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 heavy hex nut | ASTM A193 B8 · A194 8 | General corrosion resistance, food, water and architectural work |
| SS 304L heavy hex nut | ASTM A193 B8 · A194 8 | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S heavy hex nut | ASTM A276 / A479 | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L heavy hex nut | ASTM A193 B8M · A194 8M | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 heavy hex nut | ASTM A193 B8T | High-temperature service between 425 and 815 °C |
| SS 347 heavy hex nut | ASTM A193 B8C | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 heavy hex nut | ASTM A276 / A479 | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 heavy hex nut | ASTM A276 / A479 | Seawater and high-chloride service where strength also matters |
| Inconel 600 heavy hex nut | ASTM B166 | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 heavy hex nut | ASTM B446 | Seawater, high strength and high temperature in one alloy |
| Inconel 718 heavy hex nut | ASTM B637 | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT heavy hex nut | ASTM B408 | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 heavy hex nut | ASTM B574 | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 heavy hex nut | ASTM B574 | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 heavy hex nut | ASTM B164 | Seawater, hydrofluoric acid and marine service |
| Monel K500 heavy hex nut | ASTM B865 | High-strength pump shafts, bolting and springs in seawater |
Other fasteners
Stud boltA fully threaded rod supplied with two heavy hex nuts.Hex boltA bolt with a hexagonal head.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.
Heavy hex nut — questions buyers ask
Why use heavy hex nuts on flanges?
They provide more thread engagement and bearing area for the high preload flange joints need.
Which grades are heavy hex nuts 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 heavy hex nut dimensions?
ASME B18.2.2. The material standard depends on the grade.
India · Gulf · South-East Asia · South America · Europe · USA · UKSend your heavy hex nut requirement today.
Start RFQ