Whether it’s in a power plant, a chemical processing facility, or an aerospace application, cables must perform flawlessly even under the harshest conditions. Mineral insulated (MI) cables offer exceptional resilience against extreme temperatures, fire, and corrosive environments.
But what makes these cables so durable? Read on to learn more!
The Role of the Metallic Sheath in Durability
At the heart of MI cables lies the metallic sheath, which serves as the first line of defense against extreme conditions. Typically made from robust materials like stainless steel, Inconel, or copper-nickel alloys, the sheath provides outstanding corrosion resistance and mechanical strength.
For instance, in power plant environments where exposure to high temperatures and corrosive gases is constant, the metallic sheath acts as a barrier, preventing damage to the internal components. Its ability to withstand physical and chemical abrasion makes it ideal for harsh industrial applications.
Due to the sheath’s tight sealing, external contaminants, such as moisture or corrosive chemicals, are not able to compromise the internal insulation or conductors. This property is especially critical in power distribution and high-temperature conditions.
Magnesium Oxide Insulation: A Critical Component for Extreme Environments
The core of an MI cable is insulated using magnesium oxide (MgO) powder, an inorganic material that provides unparalleled performance in extreme environments. MgO serves as both an electrical insulator and a thermal conductor, allowing the cable to handle high-temperature conditions while maintaining excellent insulation resistance.
Magnesium oxide insulation is non-combustible and can endure temperatures exceeding 1000°C, making it ideal for fire resistance. In the event of a fire, MI cables maintain their functionality, ensuring critical systems like emergency lighting and alarm circuits continue to operate. This fire resistance is one of the reasons MI cables are commonly used in safety-critical infrastructure.
In addition, MgO’s inorganic nature prevents it from degrading over time, even with prolonged exposure to extreme temperatures or harsh chemicals. This stability ensures the long-term reliability of thermocouple cables and other MI cable types.
Thermocouple cables are designed to meet specific international standards, ensuring reliable and accurate temperature measurements. Some key points:
International Standards
- ASTM E585/E585M and IEC 61515 for base metal thermocouple types
- ASTM E230/E230M and IEC 584-1 for emf outputs
- ASTM E230/E230M and IEC 584-2 for calibration tolerances
Key Features of Thermocouple Cables
- Insulation: Magnesium oxide (MgO) with standard purity (> 97% pure MgO) or high purity grade (> 99.4% pure MgO)
- Insulation resistance: Minimum of 100 megohms
- Bendability: Sheath can be bent around a mandrel twice the sheath diameter without damage
- Multipair options: Simplex (1 pair), Duplex (2 pairs), Triplex (3 pairs), and Quadruplex (4 pairs)
Important Considerations
- Emf tolerances: Differences between ASTM and IEC standards should be noted
- Accuracy specifications: Care should be taken in specifying accuracies as “special”, “standard”, “class 1”, or “class 2”
- Insulation resistance: Can be affected by contamination, moisture, and temperature
High-Quality Cable Products
- Thermocouple cable is manufactured to meet strict specifications, including ASTM E585 and ASTM E235 for high-reliability applications.
Exceptional Insulation Resistance in Extreme Conditions
Insulation resistance is a key metric for evaluating the performance of electrical cables, and MI cables excel in this regard. The combination of the metallic sheath and magnesium oxide insulation ensures minimal leakage current, even under high voltage and extreme environmental conditions.
In industrial applications, such as chemical processing, where exposure to high humidity and corrosive agents is routine, maintaining insulation resistance is critical. MI cables’ ability to preserve their electrical integrity under such conditions sets them apart from other cable types. For example, in high-temperature sensor applications, the stability of MgO insulation ensures accurate readings without signal loss.
Resistance to Corrosion and Environmental Stress
Corrosion is one of the biggest challenges for cables in industrial environments. The metallic sheath of MI cables, often crafted from corrosion-resistant alloys, provides unmatched protection against aggressive chemicals, saltwater, and other corrosive agents.
For instance, in offshore oil and gas platforms, where cables are exposed to seawater and extreme temperatures, MI cables have demonstrated their ability to endure without degradation. This corrosion resistance extends the lifespan of the cables and reduces the need for frequent replacements, saving both time and resources.
Types of Mineral Insulated Cables for Specialized Applications
Not all MI cables are created equal. Different types of cables are designed to meet specific industrial requirements:
- Thermocouple Cables: Used in temperature measurement systems, these cables ensure precise and reliable data transmission, even in extreme temperature fluctuations.
- Power Distribution Cables: With their ability to handle high currents and voltages, these cables are vital for power plants and other energy-intensive facilities.
- Fire-Resistant Cables: Designed for critical safety applications, these cables maintain functionality during and after a fire, ensuring continuous operation of essential systems.
Each type of cable is optimized for its intended application, leveraging the unique properties of the metallic sheath and magnesium oxide insulation.
Applications in Power Plants and Beyond
Power plants are one of the most demanding environments for electrical components. Whether it’s monitoring boiler temperatures or controlling turbine operations, MI cables ensure reliable performance and are widely used due to their ability to withstand extreme temperatures, high pressure, and corrosive conditions.
MI cables’ durability under extreme conditions makes them a trusted choice for critical applications across industries, such as aerospace, nuclear facilities, and chemical processing plants.
Fire Resistance: A Critical Advantage
One of the standout features of MI cables is their fire resistance. Unlike organic insulation materials that can melt or emit toxic gases during a fire, magnesium oxide insulation remains intact and functional. This property is crucial for maintaining the operation of emergency systems in fire-prone environments.
A Reliable Solution for Extreme Environments
The science behind mineral insulated cables lies in their meticulous design and high-performance materials. From the corrosion-resistant metallic sheath to the fireproof magnesium oxide insulation, every component is engineered to deliver durability and reliability in extreme conditions. These qualities make MI cables indispensable in industries where safety and performance are paramount.
If you’re looking for a dependable solution for your high-temperature or safety-critical applications, explore Temp-Pro’s range of mineral insulated cables. Contact us today to discuss how our expertise can support your industrial needs.
Products:
- Industrial Thermocouples: These temperature sensors are essential in various industrial applications, providing accurate and reliable temperature measurements.
- Industrial Temperature Sensors & Probes: Designed for precision, these sensors and probes are suitable for monitoring temperatures in demanding environments.
- Thermowells: Protective devices that house temperature sensors, thermowells shield sensors
- Helical Thermowells: An advanced form of thermowell, the helical design enhances performance in high-velocity fluid streams, reducing the risk of vibration-induced failures.
- Industrial Wire Harnesses & Cable Assemblies: Custom-designed to meet specific industrial requirements, these assemblies ensure reliable electrical connections in complex systems.from harsh process conditions, ensuring longevity and accurate readings.
Neal Messier is a dedicated sales manager at Temp-Pro. With 17+ years of experience working with instrumentation in diverse industrial and process industries particularly power generation, he is passionate about the temperature sensor industry and uses his strong technical background and comprehensive industry knowledge to fulfill client’s temperature sensor needs.
Nicole Chotain is a marketing and sales specialist in the temperature sensor manufacturing industry. She focuses on enhancing her technical expertise to deliver high-precision, custom sensor solutions that meet critical industry standards, making her role both rewarding and impactful. Nicole excels at driving growth through innovative marketing strategies, building strong customer relationships, and elevating Temp-Pro’s brand reputation.
