ASTM B729 Alloy 20 (UNS N08020) Nickel Alloy Seamless Pipe for Sulfuric Acid, Chemical Processing, Pharmaceutical and Corrosive-Service Piping
ASTM B729 Alloy 20 (UNS N08020) Nickel Alloy Seamless Pipe
ASTM B729 Alloy 20 (UNS N08020) Nickel Alloy Seamless Pipes are manufactured in accordance with ASTM B729, offering excellent resistance to sulfuric acid, phosphoric acid, and various corrosive media. With good resistance to pitting, intergranular corrosion, and stress corrosion cracking, they are suitable for chemical processing, acid handling, pharmaceutical, and corrosive-service piping systems.
Key Features
- Provides strong resistance to sulfuric acid, phosphoric acid, and various corrosive media.
- Helps withstand chloride-containing and localized corrosion environments.
- Suitable for corrosive service involving welded and heat-affected areas.
- Suitable for acidic and demanding corrosive environments.
- Offers good strength and toughness for industrial piping systems.
- Seamless construction supports reliable piping applications.
Typical Applications
- Used in chemical plants, reactors, process piping, and corrosive-media transfer systems.
- Applied in sulfuric acid plants, acid transfer piping, and acid handling equipment.
- Used in pharmaceutical equipment, process piping, and corrosive chemical transfer systems.
- Applied in industrial gas treatment, flue-gas desulfurization, and corrosive wastewater treatment equipment.
- Used in heat exchangers, storage tanks, pumps, and other corrosion-resistant industrial equipment.
Chemical Composition (wt%)
| Element | Ni | Cr | Mo | Nb + Ta | Cu | Fe | Si |
|---|---|---|---|---|---|---|---|
| Range | 32.00–38.00 | 19.00–21.00 | 2.00–3.00 | 8 × C – 1.00 | 3.00–4.00 | Balance | ≤ 1.00 |
Mechanical Properties (Solution Annealed)
| Property | Value |
|---|---|
| Tensile Strength (Rm) | ≥ 550 MPa (80 ksi) |
| Yield Strength (Rp0.2) | ≥ 240 MPa (35 ksi) |
| Elongation (A5) | ≥ 30 % |
| Density | 8.08 g/cm³ |
| Hardness | ≤ 220 HBW |
| Modulus of Elasticity | 193 GPa |
| Max Service Temperature | ≤ 538°C (1000°F) |
Precautions
- Corrosion resistance depends strongly on sulfuric acid concentration and operating temperature.
- Avoid prolonged exposure to highly oxidizing media beyond the alloy’s intended service conditions.
- Maximum service temperature should be determined based on pressure, medium concentration, temperature, and applicable design codes.
- Proper pickling and passivation should be applied after fabrication when required to restore surface corrosion resistance.
Quality Assurance
Alloy 20 (UNS N08020) seamless pipes are manufactured in accordance with ASTM B729 / ASME SB729 requirements. Each pipe is fully inspected for dimensions, surface quality, chemical composition, mechanical properties and NDT as required. Full material traceability is maintained, with MTRs, heat-treatment records and inspection reports provided upon request.
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