Introduction
Sulfuric acid is widely used in chemical processing, fertilizer production, and industrial manufacturing. Selecting the right tubing material is critical to ensure plant safety, minimize downtime, and extend equipment lifespan. Hastelloy G30 and Alloy 20 are both nickel-based corrosion-resistant alloys, but they differ in chemical composition, mechanical strength, and performance in sulfuric acid environments. Understanding these differences helps engineers and procurement managers make informed decisions.
Chemical Composition Comparison
|
Element |
Hastelloy G30 (%) |
Alloy 20 (%) |
Notes |
|
Nickel (Ni) |
Balance |
Balance |
Core corrosion-resistant component |
|
Chromium (Cr) |
28–31.5 |
19–21 |
Higher Cr in G30 enhances oxidizing acid resistance |
|
Molybdenum (Mo) |
4–6 |
3–4 |
Improves pitting/crevice resistance |
|
Copper (Cu) |
1–2.4 |
3–4 |
Alloy 20 has higher Cu for moderate acid resistance |
|
Iron (Fe) |
13–17 |
≤7 |
G30 higher Fe improves structural stability |
|
Tungsten (W) |
1.5–4 |
- |
G30 has W for added corrosion resistance |
Analysis:
G30 is stronger in oxidizing sulfuric acid and high-temperature conditions
Alloy 20 is suitable for moderate concentrations and reducing acid environments
Mechanical Properties
|
Property |
Hastelloy G30 |
Alloy 20 |
Notes |
|
Tensile Strength |
≥586 MPa |
450–550 MPa |
G30 stronger for high-pressure piping |
|
Yield Strength |
≥241 MPa |
205–240 MPa |
G30 preferred for stress-critical applications |
|
Elongation |
≥30% |
≥25% |
Both alloys ductile enough for fabrication |
|
Hardness |
≤100 HRB |
≤95 HRB |
G30 slightly more wear resistant |
Corrosion Performance in Sulfuric Acid
|
Sulfuric Acid Concentration |
Hastelloy G30 |
Alloy 20 |
Recommendation |
|
<10% |
Excellent |
Excellent |
Either can be used |
|
10–40% |
Excellent |
Good |
G30 preferred for high durability |
|
40–70% |
Excellent |
Moderate |
G30 recommended |
|
>70% |
Excellent |
Poor |
Only G30 suitable |
Key Takeaway:
Hastelloy G30 is far superior in aggressive or oxidizing sulfuric acid environments, while Alloy 20 is limited to lower concentration and less demanding applications.
Industrial Applications
Hastelloy G30 Tubes
High-concentration sulfuric acid pipelines
Phosphoric acid and mixed acid systems
Heat exchangers handling oxidizing acids
Reactor internals and evaporators
Alloy 20 Tubes
Moderate sulfuric acid transfer lines
Low-to-medium pressure chemical equipment
Fertilizer production with controlled acid concentrations
Comparison Table of Applications
|
Application |
Hastelloy G30 |
Alloy 20 |
Notes |
|
High-pressure acid piping |
Excellent |
Fair |
Use G30 |
|
Heat exchanger tubes |
Excellent |
Good |
G30 is preferred for oxidizing media |
|
Fertilizer plant pipelines |
Excellent |
Good |
Alloy 20 suitable in moderate acid |
|
Reactor internals |
Excellent |
Fair |
G30 recommended |
Selecting the Right Alloy
Considerations for Selection:
Acid concentration and type
Temperature and pressure conditions
Flow velocity and contamination
Required tube dimensions and tolerances
Lifecycle cost vs initial material cost
Supplier Checklist:
ASTM B622 compliance (G30)
UNS N06030 or Alloy 20 certification
EN 10204 3.1 Mill Test Certificate
PMI verification, hydrostatic testing
Full traceability and documentation
FAQ
Q1: Can Alloy 20 replace Hastelloy G30 in high-concentration sulfuric acid?
A1: No. Alloy 20 is suitable only for moderate concentrations. G30 is preferred in harsh, oxidizing environments.
Q2: Are both alloys weldable?
A2: Yes, but G30 requires specialized welding procedures for maintaining corrosion resistance.
Q3: Which alloy has longer service life in sulfuric acid plants?
A3: Hastelloy G30, due to higher corrosion resistance and mechanical strength.
Q4: What is the UNS number for Hastelloy G30?
A4: UNS N06030.
Q5: What industries use these tubes?
A5: Chemical processing, fertilizer manufacturing, phosphoric acid plants, heat exchangers, and industrial piping systems.
Q6: Are seamless tubes better than welded tubes in sulfuric acid service?
A6: Yes. Seamless G30 tubes have uniform corrosion resistance and higher pressure ratings, while welded tubes may require post-weld annealing.
Conclusion
Hastelloy G30 tube outperforms Alloy 20 in sulfuric acid applications, especially at higher concentrations, temperatures, and in oxidizing conditions. Selecting the correct tube type ensures long service life, reduced maintenance, and safe operation.
For certified Hastelloy G30 tubes with ASTM B622 compliance, traceable material certificates, and customized dimensions, TSM Technology provides expert solutions for chemical and industrial applications.
Email: info@tsm-titanium.com
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TSM Technology, one of the leading Asian suppliers of high-performance titanium-based materials in China, specializes in factory-made products such as titanium tubes, welded titanium pipes and fittings, titanium flanges, titanium fasteners and nuts, titanium plates and rods, among others.
They are widely used in the construction of heat exchangers, condensers, power plants, seawater desalination facilities, oil and gas pipelines, chlor-alkali plants, and other related fields.
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