Common Applications Of Incoloy Capillary Tubes

What distinguishes Incoloy?

Incoloy is not a conventional metal; it is an advanced alloy. It is engineered to withstand severe conditions, including high temperatures, corrosive media and elevated pressures. It consists primarily of nickel, with minor amounts of iron and chromium; depending on the application, it may also incorporate molybdenum, copper or titanium. This material exhibits resistance to acids, high temperatures and saline environments.

Stainless steel appears shiny and stable. However, under rigorous conditions, it may develop rust or become porous, particularly in the presence of chlorides or acidic media. Incoloy maintains its dimensional integrity without degradation. Consequently, it is utilised in chemical processing plants, power stations and underwater applications.

A brief overview of the quality grades

Each grade of Incoloy meets specific performance requirements depending on the application:

• Incoloy 800/800H/800HT: These materials endure high temperatures and are resistant to oxidation and carburisation. They are suitable for use in ovens, steam generators and heat exchangers.
• Incoloy 825: This material demonstrates high resistance to acids such as sulphuric and phosphoric acid. It is employed in acid processing systems and in the reprocessing of nuclear materials.
• Incoloy 903 and A-286: These alloys exhibit ductility and stability at both low and elevated temperatures. They find application in the aerospace sector and high-pressure fuel systems.

Below is an overview table detailing the key Incoloy grades:

Additional Incoloy products are available at Stanford Advanced Materials (SAM).

General applications of Incoloy capillary tubes

This discussion does not concern standard tubes but rather capillary tubes, which are narrow and machined to precise tolerances for use in systems where accuracy is critical.

In nuclear power stations, these tubes are employed in the monitoring and control of systems whose reliability is essential. A failure could necessitate a shutdown. Incoloy tolerates both radiation and elevated temperatures better than many other materials; it is selected for such environments.

In petrochemical plants and refineries, corrosive substances such as acids and sulphides are present. Incoloy tubes withstand these substances when used in sampling lines or injection systems.

High-temperature gas systems in applications such as gas turbines or reactors rely on these tubes. They convey superheated gases that would typically cause other materials to melt or deform. Incoloy remains dimensionally stable even at temperatures of up to 1 000 °C.

The aerospace sector also utilises Incoloy. In these applications, there is no margin for leaks or failure. Incoloy tubes are employed to transport fuel and hydraulic fluid under demanding conditions, thereby providing precise flow control.

Further reading: A Guide to Inconel Used in Oil and Gas Extraction

Selecting the correct tube for the intended application

The selection of the appropriate Incoloy capillary tube is made after careful consideration. The following factors must be taken into account:

• The environment: If acids, high temperatures or chlorides are present, choose the grade accordingly.
• Pressure and temperature: Not all alloys perform identically under load. Verify that the tube meets the required temperature and pressure limits.
• Dimensional accuracy: In capillary tubes, minor deviations can lead to significant issues, particularly in flow or pressure regulation.
• Conformity and standards: In industries such as nuclear, aerospace or pharmaceuticals, documentation confirming adherence to regulations is necessary.
• Cost versus durability: Although Incoloy may present a higher initial cost compared with stainless steel, its extended service life and reduced maintenance requirements can lower overall expenses.

The following table offers a concise overview of Incoloy capillary tubes and the associated ASTM standards:

Final considerations

If you operate in environments where material failure is hazardous, you require a material with proven performance. For this reason, Incoloy capillary tubes have established their role. They are commonly employed in critical applications within the energy, aerospace and chemical processing sectors.