Proper material choice is essential for valves operating at elevated temperatures and pressures, corrosive, chloride, acidic and aggressive media. The material corrosion in such environment may influence its pressure capacity and sealing capability, and even the life of the valve itself.
Inconel Valve and Incoloy Valve are nickel-base alloy valve materials that are widely employed in industrial applications. The differences between these two materials should be taken into account during the material selection process.
As a prominent Valve Manufacturer in India,Speciality Valve offers its Inconel and Incoloy valves for applications in the oil and gas industry, petrochemicals, chemical process industry, power plants, and the maritime industry.
Inconel vs Incoloy Valves: What Is the Difference?
Understanding Inconel vs Incoloy Valves
Inconel and Incoloy valves differ in terms of their alloy composition and performance characteristics.
Inconel Valve and Incoloy Valve differ in terms of the alloy composition that they use.
The alloy for Inconel is made up of metals such as nickel and chromium. There are other metals such as molybdenum and niobium that may also be used to strengthen the metal.
Incoloy consists of the metals nickel, iron, and chromium. There are various grades developed in accordance with their resistance to high temperatures or corrosive environments.
Parameter | Inconel | Incoloy |
Alloy system | Primarily Ni-Cr | Ni-Fe-Cr |
Common grades | 600, 625 | 800, 825 |
Key property | Heat, strength, and corrosion resistance | High-temperature or chemical corrosion resistance |
Typical selection | Severe corrosive and high-temperature service | Thermal and chemical process service |
The exact alloy grade should be specified instead of treating all Inconel or Incoloy materials as having identical properties.
Inconel and Incoloy Grade Comparison:
Alloy Grade | Main Reason for Consideration | Selection Consideration |
Inconel 600 | Elevated-temperature oxidation resistance and resistance to chloride stress-corrosion cracking | Does not provide universal resistance to every chloride-related corrosion mechanism |
Inconel 625 | Resistance to localized corrosion in many chloride and seawater environments | Confirm fluid composition, temperature, deposits, and exposure conditions |
Incoloy 800 | Elevated-temperature oxidation and carburization resistance | Check the specified grade and high-temperature strength requirements |
Incoloy 825 | Selected sulfuric- and phosphoric-acid and aqueous-corrosion applications | Evaluate acid concentration, temperature, impurities, and service conditions |
Inconel Valve Grades and Corrosion Resistance:
Different Inconel valve grades provide different levels of high-temperature and corrosion performance.
Inconel 600:
Inconel 600 is a superalloy made up of nickel, chromium, and iron with good heat-resistance to oxidation. In addition, this superalloy has resistance to chloride ion stress corrosion cracking due to its composition of nickel.
This superalloy can be applied where heat oxidation resistance and mechanical stability are important. What should be emphasized is that resistance to chloride ion stress corrosion cracking is not automatically resistance to chloride pitting or crevice corrosion.
Inconel 625:
Inconel 625 contains nickel, chromium, molybdenum, and niobium as its elements. It is the molybdenum element that gives
Incoloy 800 vs Incoloy 825 Valve Performance:
Individual Incoloy grades also have distinctly different properties.
Incoloy 800
Incoloy 800 is an alloy of nickel, iron, and chromium, and it is used when high temperature properties are needed. It offers oxidation and carburization resistance along with strength at high temperatures after long exposure.
When strength at high temperatures after long exposure is needed, the designated grade in the 800 series and the relevant material specification need to be verified. Incoloy 800, 800H, and 800HT cannot be taken as interchangeable.
Incoloy 825
Incoloy 825 contains molybdenum, copper, and titanium in addition to nickel, iron, and chromium. Its composition provides resistance to several forms of aqueous corrosion.
Important characteristics include:
Resistance to pitting and crevice corrosion
Resistance to stress-corrosion cracking
Performance in selected sulfuric- and phosphoric-acid environments
Resistance to several aggressive process fluids
Incoloy 825 is another metal that might be considered for sulfuric and phosphoric acid applications. The applicability of this alloy to specific processes is dependent upon acid concentration, temperature, impurities, and the acceptable corrosion limits.
Incoloy Gate Valve is applicable for isolating services, whereas Incoloy Globe Valve is applicable for flow regulation if the alloy selected is appropriate.
Inconel vs Incoloy Corrosion Resistance:
Neither material is universally more corrosion resistant. Selection depends on the actual corrosion mechanism and operating environment.
Service Condition | Material Consideration |
Pitting and crevice corrosion | Evaluate Inconel 625 based on the fluid and exposure conditions |
Selected sulfuric- or phosphoric-acid service | Evaluate Incoloy 825 according to concentration and temperature |
High-temperature oxidation | Consider Inconel 600 or Incoloy 800 based on the required service conditions |
Chloride-containing service | Assess the corrosion mechanism and consider Inconel 625 where localized attack is a concern |
Inconel vs Incoloy Temperature Performance:
Both alloy families can perform at elevated temperatures, but their suitability depends on the specific alloy grade and service conditions.
Inconel 600 offers good oxidation resistance and mechanical stability at elevated temperatures. Incoloy 800 is also associated with high-temperature service because of its resistance to oxidation and carburization.
For high-temperature valve selection, engineers should consider:
Maximum operating and design temperature
Pressure-temperature rating
Thermal cycling
Oxidation resistance
Body and trim compatibility
Seat and packing temperature limits
Mechanical strength at elevated temperature
The temperature capability of the alloy should not be considered the temperature rating of the complete valve. Seats, packing, gaskets, trim, pressure class, and valve design can limit the final operating range.
Inconel vs Incoloy Valve Applications:
The process environment is usually the deciding factor when choosing between an Inconel Valve and Incoloy Valve.
Application | Material Consideration |
High-temperature process lines | Evaluate Inconel 600 or Incoloy 800 based on operating conditions |
Chloride-containing service | Assess the corrosion mechanism; Inconel 625 may be considered for localized corrosion concerns |
Selected acid processing | Evaluate Incoloy 825 according to acid concentration, temperature, and impurities |
Marine environments | Consider Inconel 625 for suitable chloride and seawater applications |
High-temperature isolation | Inconel Gate Valve or Incoloy Gate Valve, subject to design and material suitability |
Corrosive flow-control service | Inconel or Incoloy Globe Valve, subject to throttling and process requirements |
For suitable non-return applications, an Inconel Swing Check Valve may be evaluated according to process conditions.
Material selection must take into consideration the actual process conditions instead of selecting an alloy based on its general corrosion and temperature resistance alone. Factors that need to be considered in material selection include: Working pressure and temperature Process fluid and concentration Chloride or acid exposure Pressure class requirement Corrosion mechanism Type and purpose of valve Inconel or Incoloy grade Body, bonnet, and trim materials Seat, trim, and packing materials Applicable design and testing standards The body, bonnet, trim, and other wetted components should be identified in the valve specification. A valve described as an Inconel Valve may use the alloy in specific components rather than throughout the complete assembly. Gate valves provide isolation, while globe valves can regulate flow when the valve design and selected materials are suitable for the process conditions. It is impossible to find a material that works perfectly well in any condition. Inconel 625 is normally used when pitting, crevice corrosion and aggressive environments containing chlorides need to be resisted. On the other hand, Incoloy 825 can be considered for some applications in which sulfuric, phosphoric acid and aqueous corrosion take place. In situations where the material needs to work at high temperatures, Inconel 600 and Incoloy 800 can be considered. As a prominent Valve Manufacturer in India, Speciality Valve offers Inconel and Incoloy valves suitable for challenging industrial environments. The proper selection of the alloy grade, valve type, pressure rating, and process environment leads to enhanced performance and longevity.How to Select Inconel or Incoloy Valves?
Which Is Better: Inconel or Incoloy Valves?
