Patriot Bolt machines Alloy 20 heavy hex nuts from certified ASTM B473 bar (UNS N08020). Alloy 20 nuts pair with Alloy 20 studs so the whole joint resists sulfuric acid and chloride stress corrosion cracking.
We make Alloy 20 nuts alone or with matching studs. Every order ships with mill test reports traceable to the heat.
Alloy 20 Heavy Hex Nuts at a Glance
- Material
- Alloy 20, UNS N08020
- Bar specification
- ASTM B473 / ASME SB473
- Style
- Heavy hex to ASME B18.2.2
- Key elements
- 32–38% Ni, 19–21% Cr, 3–4% Cu, 2–3% Mo
- Matching stud
- Alloy 20 stud bolts
Why Engineers Specify Alloy 20 Nuts
- Same alloy as the stud. Matching nut and stud material avoids galvanic corrosion in acid service.
- Sulfuric acid resistance. Copper and molybdenum additions are what make Alloy 20 suited to sulfuric acid.
- Galling. Like other nickel alloys, Alloy 20 can gall. Use a compatible anti-seize on assembly.
Alloy 20 Bar Properties
Nuts are machined from ASTM B473 bar, which sets these minimum properties.
| Condition | Tensile, min | Yield (0.2%), min | Elongation, min | Reduction of area, min |
|---|---|---|---|---|
| Annealed, all sizes | 80 ksi | 35 ksi | 30% | 50% |
| Annealed and strain hardened, to 2 in | 90 ksi | 60 ksi | 15% | 40% |
Alloy 20 Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 32.0–38.0 |
| Chromium | 19.0–21.0 |
| Copper | 3.0–4.0 |
| Molybdenum | 2.0–3.0 |
| Niobium + tantalum | 8 × C min, 1.00 max |
| Manganese | 2.00 max |
| Silicon | 1.00 max |
| Carbon | 0.07 max |
| Phosphorus | 0.045 max |
| Sulfur | 0.035 max |
| Iron | Balance |
Limits per the current edition of the specification. The mill test report for your heat is the controlling document.
Nut Styles
- Heavy hex nuts to ASME B18.2.2, the standard style for flange and structural studs.
- Heavy hex jam nuts where a thinner nut is needed.
- Threads: UNC through 1 in and 8UN above 1 in, or the thread on your drawing.
Applications and Industries
- Chemical processing: Acid piping, pumps and valves. See Petrochemical & Refining.
- Pickling and metal finishing: Acid tanks and process lines. See Industrial Manufacturing.
- Pharmaceutical and specialty chemicals: Flanged equipment in corrosive service.
Certification and Traceability
Patriot Bolt is ISO 9001:2015 certified. Each Alloy 20 order includes mill test reports traceable to the heat, along with a certificate of conformance to the specification on your purchase order.
Nuts are marked with the material and our identification.
Compare Alloy 20 with other bolting grades in our Fastener Materials Matrix.
Alloy 20 Heavy Hex Nuts FAQ
Should Alloy 20 nuts be used with Alloy 20 studs?
Yes. Matching materials avoid galvanic corrosion and keep the whole joint at the same corrosion resistance.
Do Alloy 20 nuts gall?
They can, as with most nickel alloys and stainless steels. A compatible anti-seize reduces the risk.
What bar specification is used?
ASTM B473 / ASME SB473, which covers UNS N08020 bar.
Do you make matching Alloy 20 studs?
Yes. We machine Alloy 20 stud bolts, so the stud and nuts can come from one source.
Request a Quote
Send us the alloy, nut style, thread size, specification and quantity, or upload your drawing. Our team will confirm the material and lead time. Call (281) 581-0176 or request a quote.
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