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Hastelloy Alloys in Process Engineering

Material Selection Guide for Corrosion, Heat and Chemical Attacks: Hastelloy

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Introduction

Corrosion, heat, and chemical attacks are persistent threats in industries such as oil and gas, aerospace, chemical processing, and marine engineering. Selecting suitable materials is paramount to ensuring the safety, reliability, and longevity of critical components exposed to extreme environments. In this article, we’ll explore Hastelloy alloys, known for their exceptional resistance to corrosion and high temperatures, and how they solve everyday challenges in these demanding fields.

What is Hastelloy?

Hastelloy is a family of nickel-based alloys known for their ability to withstand aggressive chemical environments. These alloys are well-suited for industries commonly encountering acids, caustic materials, and high temperatures. Their resistance to localized corrosion, such as pitting, creation, and stress corrosion cracking, makes them an excellent choice for critical applications.

Why Choose Hastelloy?

Corrosion Resistance: Withstanding both oxidizing and reducing environments.
High-Temperature Strength: Retaining mechanical properties at elevated temperatures.
Longevity in Aggressive Media: Resistance to many acids (sulfuric, hydrochloric, nitric), alkalis, and chlorides.

Hastelloy Grades

HASTELLOY B-2 Alloy

HASTELLOY B-2 alloy (UNS N10665) is a solid solution-strengthened nickel-molybdenum alloy typically used in extreme reducing conditions. Compared to its predecessor, Alloy B (UNS N10001), B2 has significantly lower carbon, silicon, and iron contents, making the alloy less susceptible to reduced corrosion resistance in the weld zone in the as-welded condition. Control of other alloying elements, such as iron and chromium, addresses additional issues related to fabricability.

HASTELLOY B-3 Alloy

HASTELLOY B-3 alloy (UNS N10675) is extremely resistant to pure hydrochloric, hydrobromic, and sulfuric acids. In addition, it has greatly improved structural stability compared to the previous B-type alloy, resulting in fewer concerns during welding, fabrication, and service.

HASTELLOY C-4 Alloy

HASTELLOY C-4 alloy (UNS N06455) is the most microstructurally stable of the widely used nickel-chromium-molybdenum materials, a material renowned for its resistance to a wide range of corrosive chemicals, especially hydrochloric acid, sulfuric acid, and chlorides. This stability means that the alloy can be welded without concern for sensitization; the nucleation and growth of deleterious second-phase precipitates in the grain boundaries of the weld heat-affected zone (HAZ).

HASTELLOY C-22 Alloy

HASTELLOY C-22 alloy (UNS N06022) is a well-known and proven nickel-chromium-molybdenum material whose key properties are resistance to oxidizing and non-oxidizing chemicals and protection against pitting, crevice corrosion, and stress corrosion cracking. Its high chromium content makes it far more oxidizing media-resistant than the series standard C-276 alloy. It gives it exceptional resistance to chloride-induced pitting, an insidious and unpredictable form of corrosion to which stainless steels are susceptible.

HASTELLOY C-276 Alloy

HASTELLOY C-276 alloy (UNS N10276) is the first wrought nickel-chromium-molybdenum material to offer reduced welding issues (extremely low carbon and silicon contents). As a result, it has gained wide acceptance in chemical processes and related industries and now has a 50-year record of proven performance in a wide range of corrosive chemicals.

HASTELLOY C-2000 Alloy

HASTELLOY C-2000 alloy (UNS N06200) is unique among versatile nickel-chromium-molybdenum materials in that it intentionally adds copper, greatly enhancing its resistance to sulfuric acid. It also has a high chromium content to maximize its resistance to oxidizing chemicals and process streams contaminated with iron ions and dissolved oxygen.

HASTELLOY G-30 Alloy

HASTELLOY G-30 alloy (UNS N06030) is a nickel-chromium-iron material that has strong resistance to “wet process” phosphoric acid (P2O5). P2O5 is one of the most important industrial chemicals and the primary phosphorus source for agrochemical fertilizers. G-30 alloy also has moderate resistance to localized attack by chlorides. In addition, G-30 alloy is less susceptible to chloride-induced stress corrosion cracking than stainless steels.

HASTELLOY G-35 alloy

HASTELLOY G-35 alloy (UNS N06035) was developed to resist “fertilizer grade” phosphoric acid (P2O5) used in the production of fertilizers. Testing in actual solutions has shown that G-35 alloy performs far better than other metallic materials in this acid. It is also designed to resist localized attack in the presence of chlorides, as this can be a problem beneath evaporator deposits that concentrate “fertilizer grade” phosphoric acid. In addition, G-35 alloy is much less susceptible to chloride-induced stress corrosion cracking than the stainless steels and nickel-chromium-iron alloys traditionally used for “fertilizer grade” phosphoric acid.

HASTELLOY X

HASTELLOY X alloy (UNS N06002) is a nickel-chromium-iron-molybdenum alloy with excellent oxidation resistance, machinability, and high-temperature strength. It has also been found to resist stress corrosion cracking in petrochemical applications. X alloy exhibits good ductility after 16,000 hours of extended exposure at temperatures of 1200, 1400, and 1600°F (650, 760, and 870°C).

Chemical Composition

Grades B-2 B-3 C-4 C-22 C-276 C-2000 G-30 G-35 X
Elements (wt.%)
Ni Bal. 65 min. 65 Bal. 56 Bal. 57 Bal. 59 Bal. 43 Bal. 58 Bal. 47 Bal.
Mo 26.0 to 30.0 28.5 16 13 16 16 5.5 8.1 9
Cr 1.00 Max. 1.5 16 22 16 23 30 33.2 22
Fe 2.00 Max. 1.5 3 max. 3 5 3 max. 15 2 max. 18
W 3 max. 3 4 2.5 0.6 max. 0.6
Mn 1.00 Max. 3 max. 1 max. 0.5 max. 1 max. 0.5 max. 1.5 max. 0.5 max. 1 max.
Co 1.00 Max. 3 max. 2 max. 2.5 max. 2.5 max. 2 max. 5 max. 1 max. 1.5
Al 0.5 max. 0.5 max. 0.4 max. 0.5 max.
Ti 0.2 max. 0.7 max. 0.15 max.
Si 0.10 Max. 0.1 max. 0.08 max. 0.08 max. 0.08 max. 0.08 max. 0.8 max. 0.6 max. 1 max.
C 0.02 Max. 0.01 max. 0.01 max. 0.01 max. 0.01 max. 0.01 max. 0.03 max. 0.05 max. 0.1
Nb 0.2 max. 0.8 0.5 max.
V 0.2 max. 0.35 max. 0.35 max.
Cu 0.2 max. 0.5 max. 0.5 max. 0.5 max. 1.6 2 0.3 max.
Ta 0.2 max. 0.008 max.
Zr 0.01 max.
B
P 0.040 Max.
S 0.030 Max.
Reactor is Made of Hastelloy Alloys

The reactor is Made of Hastelloy Alloys

Common Concerns: Hastelloy

1. Corrosion in Chemical Processing

Corrosion is a constant concern in industries that deal with acids, caustic solutions, and complex chemical reactions. Hastelloy alloys such as C276 and C22 provide robust protection against pitting, crevice corrosion, and stress corrosion cracking. They ensure critical infrastructure lasts longer and requires less maintenance, reducing downtime and improving safety in highly corrosive environments.

2. High-Temperature Degradation in Aerospace and Power Generation

Materials exposed to high temperatures can suffer from oxidation and mechanical strength loss over time. Hastelloy X is specifically designed to maintain its strength and oxidation resistance, making it ideal for aerospace engines, turbines, and petrochemical applications. It enables components to withstand the rigors of extreme temperatures without degradation, ensuring both performance and safety.

3. Material Failures in Marine Environments

Marine environments, with their high salinity and corrosive conditions, can be extremely harsh on metals. Hastelloy C22’s resistance to seawater and chloride-induced corrosion makes it a popular choice for marine engineering. Whether used in offshore oil platforms or coastal chemical plants, Hastelloy alloys provide lasting protection against the damaging effects of saltwater corrosion.

4. Costly Maintenance Due to Short Service Life

Maintenance in oil and gas or chemical processing is costly and dangerous. Using Hastelloy alloys with superior corrosion and heat resistance can significantly reduce the frequency of repairs and replacements. This leads to increased operational efficiency and reduced overall maintenance costs, making it an economically sound choice in the long term.

Selection Guidelines: Hastelloy

When selecting a Hastelloy alloy, it’s essential to consider the specific environment the material will be exposed to, such as:
Corrosive Media: Determine whether the environment involves acids, alkalis, salts, or mixed chemical environments.
Temperature: Evaluate the operating temperature to ensure the alloy retains its mechanical properties at elevated temperatures.
Oxidizing vs. Reducing Conditions: Some Hastelloy alloys perform better in reducing environments (e.g., B2 and B3), while others excel in oxidizing conditions (e.g., C276 and C22).

Conclusion

The Hastelloy offers unparalleled solutions to corrosion, heat, and chemical attacks in critical industries such as oil and gas, chemical processing, marine engineering, and aerospace. Whether your concern is preventing corrosion in hydrochloric acid or ensuring strength in high-temperature turbine engines, Hastelloy alloys provide the reliability and durability needed to face these challenges head-on. For those in industries where failure is not an option, selecting the suitable material can be the difference between success and catastrophe. By opting for Hastelloy alloys, investing in long-term safety, performance, and cost-effectiveness, ensuring your equipment and infrastructure withstand the most aggressive conditions.

If you need help selecting the suitable Hastelloy alloy or have buying requirements for your projects, feel free to contact us at [email protected] for a professional guide or the best quote!

INCOLOY vs. HASTELLOY

INCOLOY vs. HASTELLOY: A Comprehensive Comparison for Industrial Applications

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Introduction

In industries like oil and gas, aerospace, chemical processing, marine engineering, and heat treatment, the choice of material can significantly impact equipment’s efficiency, safety, and longevity. INCOLOY vs. HASTELLOY is two high-performance alloys often compared in these fields. Both nickel-based alloys offer exceptional resistance to corrosion and heat, but their specific applications and characteristics vary based on environmental demands. This post will detail the essential differences between INCOLOY and HASTELLOY, focusing on their chemical composition, properties, advantages, and typical applications. By the end, you will clearly understand which alloy suits your particular needs.

Overview of INCOLOY

SMC developed INCOLOY, a family of nickel-iron-chromium alloys. These alloys offer high strength and resist oxidation, carburization, and sulfidation, making them ideal for high-temperature environments. Industries that require resistance to corrosive environments commonly use INCOLOY alloys, though extreme heat resistance, like that of HASTELLOY, is not always needed.

INCOLOY Grades

INCOLOY 800: Known for its strength and stability in high-temperature applications, commonly used in heat exchangers, chemical and petrochemical processing, and furnace components.
INCOLOY 825 offers excellent resistance to reducing acids like sulfuric and phosphoric acids, making it suitable for chemical processing, marine engineering, and oil and gas production.

Chemical Composition

INCOLOY alloys typically contain:
Nickel: 30-46%
Chromium: 19-23%
Iron: Balance
Molybdenum and Copper (in specific grades for enhanced corrosion resistance)

Properties

Corrosion Resistance: Excellent in acidic environments, especially against sulfuric and phosphoric acids.
Oxidation Resistance: Good at elevated temperatures.
Mechanical Strength: High strength and resistance to stress corrosion cracking.
Ease of Fabrication: INCOLOY alloys are more straightforward to machine and fabricate than other high-performance alloys.

Overview of HASTELLOY

HASTELLOY is a family of nickel-molybdenum or nickel-chromium-molybdenum alloys produced by Haynes International. These alloys resist various chemical environments, especially under extreme temperatures and pressures. HASTELLOY is particularly effective in environments involving strong acids and high temperatures, where other materials corrode rapidly.

HASTELLOY Grades

HASTELLOY C-276: Known as the most versatile corrosion-resistant alloy, it is widely used in chemical processing, pollution control, pulp and paper production, and waste treatment.
HASTELLOY C-22: Offers superior resistance to both oxidizing and reducing environments, making it ideal for industries such as pharmaceuticals, marine engineering, and flue gas desulfurization.

Chemical Composition

HASTELLOY alloys typically contain:
Nickel: 50-70%
Chromium: 14-16%
Molybdenum: 15-17%
Iron, Tungsten, and Cobalt (depending on the specific grade)

Properties

Corrosion Resistance: Exceptional resistance to a broad range of chemicals, particularly in harsh acidic environments.
Oxidation Resistance: Excellent at high temperatures, especially in reducing environments.
High-Temperature Strength: Retains strength and stability even at extreme temperatures.
Ease of Fabrication: Due to its high strength and resistance, machines and fabricates are more challenging

Heat Exchanger & Pressure Vessel

Heat Etheiranger & Pressure Vessel

INCOLOY vs. HASTELLOY: A Comparative Analysis

Feature INCOLOY HASTELLOY
Primary Elements Nickel, Iron, Chromium Nickel, Chromium, Molybdenum
Corrosion Resistance Suitable in oxidizing and mildly corrosive environments Excellent in harsh chemical environments (acids, chlorides)
Heat Resistance Moderate to high Exceptional at high temperatures
Mechanical Strength High Very high
Cost Lower compared to HASTELLOY Higher due to superior performance
Ease of Fabrication More accessible to machine and weld More difficult due to the toughness
Typical Applications Heat exchangers, chemical processing, marine Chemical processing, pollution control, marine engineering

Applications: INCOLOY vs HASTELLOY

INCOLOY Applications

Oil and Gas: Oil and gas extraction widely uses INCOLOY alloys, such as INCOLOY 825, especially for components exposed to sour gas and brine.
Marine Engineering: The alloy’s resistance to corrosion in seawater makes it ideal for marine environments.
Heat Treatment: INCOLOY alloys are commonly used in furnace parts and heat exchangers due to their high-temperature strength.

HASTELLOY Applications

Chemical Processing: HASTELLOY C-276 is the material of choice for equipment handling corrosive chemicals, especially in producing sulfuric, hydrochloric, and phosphoric acids.
Aerospace: HASTELLOY alloys are used in aircraft components that withstand extreme heat and corrosion.
Marine Engineering: HASTELLOY is often preferred in marine environments where chloride stress corrosion is a concern.
Heat Treatment: HASTELLOY’s ability to maintain mechanical properties at high temperatures makes it suitable for heat exchangers and reactors in extreme environments.

Selection: INCOLOY vs HASTELLOY

The decision to use INCOLOY or HASTELLOY largely depends on the application’s specific environmental and operational conditions. Here are some general guidelines:
HASTELLOY is the better choice for applications with high levels of acidic or corrosive chemicals, particularly under extreme temperatures, because it offers superior chemical resistance.
INCOLOY delivers excellent performance at a lower cost in high-temperature applications that don’t involve highly corrosive environments.
When easier fabrication is required without sacrificing corrosion resistance, INCOLOY is generally preferred for its machinability.
HASTELLOY is the best option for situations involving extreme heat and harsh chemicals, such as chemical reactors or pollution control equipment.

Conclusion

Both INCOLOY and HASTELLOY offer distinct advantages depending on the industry and environment. INCOLOY excels in less harsh environments, providing high strength and moderate corrosion resistance at elevated temperatures. In contrast, HASTELLOY is the go-to material for extreme conditions involving high temperatures, corrosive chemicals, and demanding mechanical stress.

When choosing between these two alloys, consider your application’s specific chemical and thermal conditions. Consulting with materials experts and suppliers can also help tailor the alloy selection to your operational needs, ensuring long-lasting, reliable performance.

By understanding the critical differences between INCOLOY and HASTELLOY, industries like oil and gas, aerospace, and chemical processing can make informed decisions that optimize performance, safety, and cost-efficiency.