Inconel vs Incoloy Valves: Temperature and Corrosion Performance

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.

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.

For suitable non-return applications, an Inconel Swing Check Valve  may be evaluated according to process conditions.

How to Select Inconel or Incoloy Valves?

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.

Which Is Better: Inconel or Incoloy Valves?

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.