Alloy 20 / 020，Carpenter 20Cb-3 Tube，UNS N08020,E FORU

British Specs:，American Specs:，German Specs: WS 2.4660

**Product Name:** Alloy 20 / Carpenter 20Cb-3® Tube | UNS N08020 **Material Type:** Nickel-Iron-Chromium Austenitic Stainless Steel Tube **Standard:** ASTM B729, ASME SB729, ASTM B775 --- ### **Overview** Alloy 20 Tube (UNS N08020), commercially known as **Carpenter 20Cb-3®**, is a nickel-iron-chromium austenitic stainless steel tube specifically designed for handling sulfuric acid and other aggressive chemical media. Available in both seamless and welded forms, this alloy offers exceptional corrosion resistance combined with excellent mechanical properties, making it ideal for heat exchangers, condensers, and process tubing in corrosive environments. --- ### **Key Advantages** - **Exceptional Sulfuric Acid Resistance:** Superior performance in sulfuric acid service up to 95°C - **Chloride Stress Corrosion Cracking Resistance:** Excellent resistance in chloride-containing environments - **Enhanced Mechanical Properties:** Optimal combination of strength and ductility - **Excellent Heat Transfer Characteristics:** Ideal for heat exchanger applications - **Good Fabricability:** Easy to weld, bend, and form - **Long Service Life:** Reduced maintenance and downtime costs --- ### **Chemical Composition (Typical Weight %)** | Element | Content (%) | Element | Content (%) | |---------|-------------|---------|-------------| | Nickel (Ni) | 32.0-38.0 | Chromium (Cr) | 19.0-21.0 | | Iron (Fe) | Balance | Molybdenum (Mo) | 2.0-3.0 | | Copper (Cu) | 3.0-4.0 | Manganese (Mn) | ≤2.0 | | Silicon (Si) | ≤1.0 | Carbon (C) | ≤0.07 | | Niobium (Nb) | 8×C-1.0 | Phosphorus (P) | ≤0.045 | | Sulfur (S) | ≤0.035 | | | --- ### **Physical & Mechanical Properties** #### **Physical Properties** - **Density:** 8.08 g/cm³ (0.292 lb/in³) - **Melting Range:** 1440-1500°C (2620-2730°F) - **Thermal Expansion Coefficient:** 15.9 × 10⁻⁶/°C (20-100°C) - **Modulus of Elasticity:** 186 GPa (27 × 10⁶ psi) - **Thermal Conductivity:** 12.9 W/m·K at 100°C - **Specific Heat Capacity:** 500 J/kg·K at 100°C #### **Mechanical Properties (Annealed Condition)** | Property | Typical Value | |----------|---------------| | Tensile Strength | 620-690 MPa (90-100 ksi) | | Yield Strength (0.2% Offset) | 300-415 MPa (44-60 ksi) | | Elongation | 30-50% | | Hardness | 150-190 HB | | Shear Modulus | 75 GPa (10.9 × 10⁶ psi) | --- ### **Product Specifications** #### **Tube Specifications** - **Outside Diameter:** 1/8" to 4" (3.18 mm to 101.6 mm) - **Wall Thickness:** 0.015" to 0.250" (0.38 mm to 6.35 mm) - **Length:** Standard 20 feet, cut lengths available - **Types:** Seamless, Welded and Drawn, Welded - **Tolerances:** Per ASTM B729 requirements #### **Standard Specifications** - **ASTM B729:** Seamless and Welded Tube - **ASME SB729:** Tube for ASME Code Applications - **ASTM B775:** General Requirements for Nickel Alloy Tube #### **Surface Finishes** - Annealed and pickled - Bright annealed - Polished (ID/OD) - Special finishes upon request --- ### **International Standards & Certifications** - **UNS:** N08020 - **ASTM/ASME:** B729/SB729 - **EN:** 10216-5 (Technical Delivery Conditions) - **ISO:** 1127 (Stainless Steel Tube Dimensions) - **Certifications:** NACE MR0175, PED 2014/68/EU, ISO 15156 --- ### **Applications** #### **Heat Exchanger Applications** - Shell and tube heat exchangers - Condenser tubes - Evaporator tubes - Reboiler tubes - Process cooler tubes #### **Chemical Processing** - Heat exchanger tubing in sulfuric acid service - Process reaction tubes - Chemical transfer lines - Acid concentration systems - Pharmaceutical processing equipment #### **Food & Pharmaceutical** - Heat exchanger tubes in food processing - Pharmaceutical reaction vessels - Sanitary processing systems - High-purity fluid transfer #### **Industrial Applications** - Pollution control equipment - Waste treatment systems - Industrial cooling systems - Process heating systems --- ### **Fabrication & Installation** #### **Welding Procedures** - **Preferred Methods:** GTAW (TIG), Orbital Welding - **Filler Metals:** Alloy 20, ERNiCrFe-11 - **Shielding Gas:** 100% Argon for optimal results - **Purge Gas:** Required for interior protection - **Heat Input Control:** Moderate to low heat input recommended #### **Tube Expansion** - **Maximum Expansion:** 8-10% of tube wall thickness - **Lubrication:** Recommended for smooth expansion - **Tooling:** Hardened steel or carbide tools #### **Bending & Forming** - **Cold Bending:** Minimum bend radius 2x tube diameter - **Mandrel Bending:** Recommended for thin walls - **Heat Treatment:** Stress relief after severe forming --- ### **Corrosion Resistance** #### **Chemical Resistance** - **Excellent:** Sulfuric acid (all concentrations to 95°C) - **Good:** Phosphoric acid, nitric acid, organic acids - **Resistant:** Chloride stress corrosion cracking - **Limited:** Hydrochloric acid, oxidizing chlorides #### **Special Features** - Copper content enhances sulfuric acid resistance - Niobium stabilization prevents sensitization - Balanced composition for wide corrosion resistance - Superior to 316L and 317L in many applications --- ### **Quality Assurance** #### **Testing & Inspection** - Hydrostatic or pneumatic testing - Eddy current testing - Ultrasonic examination - Dimensional verification - Surface finish inspection #### **Certification** - Mill test certificates to EN 10204 3.1/3.2 - Full material traceability - NACE MR0175/ISO 15156 compliance - PED certification for pressure applications --- ### **Pressure-Temperature Ratings** | Temperature (°C) | Maximum Allowable Stress (MPa) | |------------------|-------------------------------| | -29 to 38 | 138 | | 100 | 138 | | 150 | 128 | | 200 | 119 | | 250 | 111 | --- ### **Conclusion** Alloy 20/Carpenter 20Cb-3® Tube provides an outstanding combination of corrosion resistance, mechanical strength, and fabrication versatility for handling aggressive chemical media. Its superior performance in sulfuric acid and chloride-containing environments, combined with excellent heat transfer characteristics, makes it the preferred choice for heat exchanger and process tubing applications in chemical processing, pharmaceutical, and industrial sectors. The availability in both seamless and welded forms ensures optimal solutions for various application requirements, delivering long-term reliability and cost-effective performance in demanding service conditions. --- *Carpenter 20Cb-3® is a registered trademark of Carpenter Technology Corporation. All technical data are typical values and should be verified for specific applications. Consult manufacturer's specifications for project-specific requirements and applicable codes and standards.*

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 2668 gallon liquid totes Special package is available on request.