What Materials Are Used in the Construction of Process Towers & Columns, and Are They Suitable for Our Fluids and Corrosion Environment?

Selecting the wrong material of construction for your process tower or column can result in accelerated corrosion, frequent shutdowns, contamination, and complete structural failure. The stakes are high—especially in corrosive chemical environments involving acids, chlorides, or elevated temperatures. Unfortunately, many engineers rely on default materials like carbon steel or 316L stainless steel without considering long-term compatibility, stress corrosion cracking, or sour service resistance. The good news is that by carefully matching tower materials to your fluid chemistry and environmental conditions, you can dramatically increase reliability, reduce lifecycle costs, and avoid catastrophic corrosion. This article offers a complete guide to the materials used in process tower construction—and whether they are suitable for your process fluids and operating conditions.

The most common materials used for process towers and columns include carbon steel, stainless steels (304L, 316L), duplex stainless steels, high-alloy materials (e.g., Hastelloy, Inconel, Monel), titanium, fiberglass-reinforced plastics (FRP), and lined steel. The suitability of each depends on fluid composition, corrosiveness, temperature, pressure, and mechanical requirements. Proper material selection is critical to ensure corrosion resistance, safety, and long-term performance.

Keep reading for a detailed breakdown of corrosion resistance, thermal tolerance, mechanical integrity, and chemical compatibility for each material—and learn how to select the ideal material for your specific process.

Most Common Materials Used in Tower and Column Construction

1. Carbon Steel (CS – ASTM A516 Gr. 70)

• Use Case: Non-corrosive or mildly corrosive services, e.g., ammonia, hydrocarbons, air
• Strengths: Low cost, good weldability, high availability
• Weaknesses: Rapidly corrodes in presence of acids, chlorides, moisture, or oxidizers
• Temperature Range: -29°C to 427°C (depending on thickness)
• Not suitable for: Acidic, moist, or corrosive streams unless lined or coated

2. 304L / 316L Stainless Steel

• Use Case: Moderate corrosion services—organic acids, mild chlorides, some solvents
• Strengths:
  • 316L has molybdenum → better pitting and crevice corrosion resistance than 304L
  • Passivating film resists oxidation
• Weaknesses:
  • 316L still susceptible to chloride stress corrosion cracking (CSCC)
  • Sensitive to high-temperature scaling above 870°C
• Temperature Range: Up to 870°C (intermittent)
• Corrosion Resistance: Good for neutral/acidic aqueous environments (up to ~500 ppm Cl⁻)

3. Duplex Stainless Steels (2205 / 2507)

• Use Case: Brine, seawater, wet chlorides, H₂S gas systems
• Strengths:
  • High strength and CSCC resistance
  • Better mechanical properties than austenitic SS
• Weaknesses: More expensive, requires specialized welding
• Temperature Range: 260–315°C (upper limit lower than austenitic grades)

4. High-Performance Alloys (Hastelloy, Inconel, Monel)

Temperature Resistance: Up to 1040°C depending on alloy
Cost: 3–10x higher than stainless steels
Application Criteria: Used only when failure would be catastrophic or corrosion rate is unacceptable

5. Titanium (Gr. 2, Gr. 7)

• Use Case: Chlorine systems, seawater, strong oxidizers
• Strengths: Forms a strong oxide layer for corrosion resistance; excellent in wet chlorine
• Weaknesses: High cost, fabrication complexity
• Temperature Range: -250°C to ~600°C
• Often Used In: Bleach towers, desalination systems

6. Fiberglass Reinforced Plastic (FRP)

• Use Case: Low-pressure acidic environments (e.g., HCl scrubbers)
• Strengths: Lightweight, corrosion-resistant, non-metallic
• Weaknesses: Limited temperature (usually < 93°C), lower mechanical strength
• Best For: Fume scrubbing, low-pressure gas absorption, outdoor stacks

7. Lined Steel (Rubber, PTFE, Glass, Epoxy)

• Use Case: When CS or SS shell cannot resist aggressive media
• Types:
  • PTFE-lined: Broad chemical compatibility, excellent for HCl, HF, mixed acids
  • Rubber-lined: Good for dilute sulfuric acid, phosphoric acid
  • Glass-lined: Pharmaceutical or high-purity applications

Limitation: Liner damage can lead to catastrophic failure—strict QA/QC and inspection needed.

Corrosion Compatibility Table: Common Fluids vs. Material Suitability

Legend: ✅ Suitable | ⚠ Limited or Conditional | ❌ Not Suitable

Summary

The material you choose for your process tower or column must align with the chemical nature of your fluids, temperature, pressure, and mechanical demands. While carbon steel and 316L stainless steel serve well in many environments, aggressive chemicals, chlorides, or high temperatures may demand duplex, nickel alloys, titanium, or specialty linings. Always consult corrosion data, material test certificates, and process specifications before finalizing material selection. Choosing correctly means better uptime, fewer failures, and superior ROI.

Need Help Matching Materials to Your Process?

We provide full material selection support, including corrosion modeling, ASME code compliance, and chemical compatibility checks. Whether you need a new tower or are retrofitting an old one, we ensure it’s built with the right materials for your environment. Contact us today to discuss your fluids, design conditions, and get a fast, accurate recommendation.