1. Austenitic Stainless Steel Castings (304, 316 Series)

• Core Composition: Chromium (16%-25%), nickel (8%-22%), and low carbon (≤0.08%). The 316 series adds 2%-3% molybdenum for improved corrosion resistance. Common grades: CF8 (304), CF8M (316), CF3M (316L low carbon).
• Key Features: Resists organic acids, weak inorganic acids, and salt solutions; operates at -270℃ to 870℃; non-magnetic; easy to weld and machine.
• Performance Traits: Prevents rust and pitting in most neutral and slightly corrosive environments. The 316 series outperforms 304 in chloride-rich media (e.g., seawater, brines).
• Typical Applications: Storage tank fittings, pump casings, valve bodies, heat exchanger tubes, and piping for acetic acid, ethanol, and food-grade chemicals.
• Pros & Cons: Pros – Cost-effective, versatile, and easy to process. Cons – Prone to stress corrosion cracking (SCC) in high-chloride, high-temperature environments.

2. Duplex Stainless Steel Castings (2205, 2507 Series)

• Core Composition: Chromium (21%-27%), nickel (4%-7%), molybdenum (2%-4%), and nitrogen (0.15%-0.3%). Common grades: CD4MCuN (2205), CE2507 (2507 super duplex).
• Key Features: High tensile strength (≥600MPa); resists pitting, crevice corrosion, and SCC; operates at -50℃ to 300℃; twice as strong as austenitic stainless steel.
• Performance Traits: Performs well in aggressive media like sour water, sulfuric acid, and chloride solutions; maintains structural integrity under high pressure.
• Typical Applications: Oil and gas chemical processing equipment, desalination components, acid recovery systems, and brine handling valves.
• Pros & Cons: Pros – High strength, superior corrosion resistance, cost-effective vs. nickel alloys. Cons – Limited high-temperature performance (above 300℃), more expensive to produce than austenitic grades.

3. Nickel-Based Alloy Castings (Hastelloy, Inconel, Monel)

• Core Composition: 40%-70% nickel, combined with chromium, molybdenum, tungsten, or copper. Common grades: Hastelloy C276, Inconel 625, Monel 400.
• Key Features: Resists strong acids (sulfuric, hydrochloric, nitric), alkalis, and molten salts; operates at -200℃ to 1200℃ (varies by grade); excellent thermal stability.
• Performance Traits: Hastelloy C276 resists pitting/crevice corrosion in mixed acids; Inconel 625 excels at high-temperature oxidation; Monel 400 is ideal for hydrofluoric acid and seawater.
• Typical Applications: Reactor vessels, catalyst supports, high-temperature furnace components, and piping for strong acid processing (e.g., sulfuric acid production).
• Pros & Cons: Pros – Extreme corrosion resistance, high-temperature tolerance. Cons – High material and production costs, limited machinability.

4. Titanium Alloy Castings

• Core Composition: Over 90% titanium, plus alloying elements like aluminum, vanadium, or palladium. Common grades: Ti-6Al-4V, Ti-Pd (palladium-enhanced for acid resistance).
• Key Features: Resists most organic/inorganic acids (except hydrofluoric acid), chlorine, and oxidizing media; operates at -250℃ to 500℃; low density (4.5g/cm³) for lightweight designs.
• Performance Traits: Forms a dense oxide film to prevent corrosion; maintains strength at elevated temperatures; biocompatible for pharmaceutical and food chemical applications.
• Typical Applications: Pharmaceutical processing equipment, high-purity chemical storage tanks, chlor-alkali process components, and acid electrolysis cells.
• Pros & Cons: Pros – Unmatched corrosion resistance, lightweight, high strength. Cons – Very high cost, difficult to cast and machine, susceptible to hydrogen embrittlement.

5. High-Chromium Cast Iron Castings

• Core Composition: Chromium (12%-30%), carbon (2%-4%), plus molybdenum or nickel for improved toughness. Common grades: Cr15Mo3, Cr20NiMo.
• Key Features: Resists mild acids, alkalis, and abrasive slurries; hardness up to HRC65; operates at -20℃ to 400℃; cost-effective vs. nickel or titanium alloys.
• Performance Traits: Hard chromium carbides provide abrasion resistance, while a chromium oxide film offers corrosion protection. Suitable for slurry handling and mixing equipment.
• Typical Applications: Slurry pumps, mixer impellers, valve seats, and hoppers for abrasive chemical mixtures (e.g., mineral slurries, fertilizer processing).
• Pros & Cons: Pros – Balanced corrosion/abrasion resistance, low cost. Cons – Brittle at low temperatures, limited resistance to strong acids.

Key Selection Criteria for Corrosion Resistant Castings in Chemical Plants

• Chemical Medium: Strong acids (sulfuric, hydrochloric) → Nickel-based alloys/Titanium; Chloride-rich media → Duplex stainless steel/316 series; Abrasive slurries → High-chromium cast iron.
• Operating Temperature: High temperature (500℃+) → Inconel/Hastelloy; Low temperature (-50℃ and below) → Austenitic stainless steel/Titanium; Moderate temperature → Duplex stainless steel.
• Pressure & Strength: High pressure → Duplex stainless steel/Nickel-based alloys; Lightweight design → Titanium; General pressure → Austenitic stainless steel.
• Budget & Compliance: Cost-sensitive → 304/316 stainless steel; High-performance needs → Nickel-based alloys/Titanium; Food/pharmaceutical → Titanium/316L (low carbon).

Why Quality Corrosion Resistant Castings Matter for Chemical Plants