
High Accuracy Mineral Insulated Cable for Thermocouple
1. Description
Mineral Insulated thermocouple cables are the core material to produce thermocouples. It typically comprises stainless steel or Inconel sheath, Magnesium Oxide (MgO) powder and thermoelectric conductors ; Magnesium Oxide (MgO) powder is disposed in the sheath to maintain separation and electrical isolation between the sheath and the thermoelectric conductors . Magnesium oxide (MgO) is preferably used as the insulation material for the MI thermocouple cables because it is stable at high temperatures and pressure .It provides a high electricity resistance and is also economical .
2. Feature
1). The metal sheath can protect the inner thermocouple conductor
against contamination, makes it moisture proof , weldable, compact
and mechanically strong.
2). MI insulated thermocouple cable make it easy to make
thermocouple in small diameter ;
3). The small mass and high thermal conductivity of a properly made
cable enables fast thermal response of the finished thermocouple
assembly.
4). Different sheath materials can be selected to offer strong
resistance against corrosive and extremely high temperature
environments.
3. Sheath Material
SS304
Max. temperature: 900°C (1650°F).
This sheath material is most widely used in low temperature . Mainly used in chemical, food, beverage, and other industries where corrosion resistance is a must, which is also the lowest cost corrosion resistant sheath material . Subject to damaging carbide precipitation in 482°C to 871°C (900° to 1600°F) range.
SS321
Max. temperature: 871°C (1600°F). Quite similar to stainless steel
304 except titanium stabilized for intergranular corrosion. SS321
is used to overcome susceptibility to carbide precipitation in the
482° to 871°C (900° to 1600°F) range. Main applications are
aerospace and chemical .
SS316
Max. temperature: 900°C (1650°F). It is the best corrosion
resistance of the austenitic stainless steel grades. Good corrosion
resistance in H2S. Mostly used in the food and chemical industry.
Subject to damaging carbide precipitation in 482° to 871°C (900° to
1600°F) range.
SS310
Max. temperature: 1150°C (2100°F). Similar to but better than 304
SS in mechanical and corrosion resistance. Also good in heat
resistance. SS310 contains 25% Cr, 20% Ni. Not as ductile as 304
SS.
Inconel 600
Maximum temperature: 1177°C (2150°F) Continuous; 1260°C (2300°F)
Intermittent. Similar to Alloy 600 with the addition of aluminum
for remarkable oxidation resistance. Used for high temperature
corrosion resistance , especially good in carburizing environments
with good creep rupture strength. Can’t be used in vacuum furnaces!
Susceptible to intergranular attack by prolonged heating in 538° to
760°C (1000° to 1400°F) temperature range.
4. Chemical Composition
Sheath Material | Chemical Composition | Max. Temp. In Air | Melting Temp. | |||||||
C | Si | Mn | P | S | Cr | Ni | Others | |||
SS304 | ≤0.07 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.03 | 17-19 | 8-11 | - | 900℃ | 1405℃ |
SS321 | ≤0.12 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.03 | 17-19 | 8-11 | 5(C%-0.02)~0.08 | 870℃ | 1400℃ |
SS316 | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.03 | 16-19 | 11-14 | Mo: 1.8-2.5 | 925℃ | 1370℃ |
SS310 | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.03 | 24-26 | 19-22 | Ti: 5C%-0.07 | 1090℃ | 1405℃ |
INC600 | ≤0.15 | ≤0.50 | ≤1.00 | ≤0.030 | ≤0.015 | 14-17 | >72 | Fe: 6-10, Cu: <0 | 1090℃ | 1400℃ |
5. Sheath Specification
Sheath material | Sheath OD (mm) | Wall Thickness (mm) | Wire Dia. (mm) | Coil Length(m) |
SS304 SS321 SS316 | 3.0 | 0.30-0.48 | 0.45-0.60 | 100 |
3.2 | 0.32-0.58 | 0.48-0.68 | 100 | |
4.0 | 0.40-0.62 | 0.60-0.70 | 70 | |
4.8 | 0.48-0.83 | 0.72-0.85 | 70 | |
5.0 | 0.50-0.85 | 0.75-0.90 | 50 | |
6.0 | 0.60-1.08 | 0.90-1.10 | 50 | |
6.4 | 0.64-1.15 | 0.92-1.12 | 40 | |
8.0 | 0.80-1.44 | 1.20-1.40 | 30 |
6. Calibration Tolerance
Conductor | Calibration | Accuracy | |||
I | II | ||||
Tolerance | Temperature | Tolerance | Temperature | ||
Ni Cr - Ni Si | K | 1.5 or 0.4%t | -40~1000 | 2.5 or 0.75%t | -40~1000 |
Ni Cr Si- Ni Si | N | -40~1000 | -40~1000 | ||
Ni Cr - Konstantan | E | -40~800 | -40~800 | ||
Fe - Konstantan | J | -40~750 | -40~750 | ||
Cu - Konstantan | T | 1.5 or 0.4%t | -40~350 | 1 or 0.75%t | -40~350 |
Pt Rh 10 - Pt | S | 1 or 1+(t-1100)x0.003 | 0~1600 | 1.5 or 0.25%t | 0~1600 |
Pt Rh 13 - Pt | R | 0~1600 | 0~1600 | ||
Pt Rh 13 - Pt Rh 6 | B | --- | --- | 600~1700 |
Wuhan Global Metal Engineering Co., Ltd
Wuhan Global Metal Engineering Co., Ltd (GME) specialize in the supply of heating elements and temperature sensors(thermocouples & RTDs) for a vast array of industries since year 1995.
Our main products include but not limited to Coil heater, Cartridge heater, Flexible Tubular heater, Cast-in Heater, Band heater, Thermocouple, RTD’s, Thermocouple extension wire, Thermocouple connection head , Mineral Insulated thermocouple cables , thermowell, etc.
After 20 years growth, we have more than 200 employees in the factory including 50 sophisticated technicians. Our products have been exported to many countries including North America, South America, Europe, Middle East ,South Asia, etc.
More details, you can also visit our website: https://www.gmemetal.com