Thermocouple protection tubes have two main uses: one is to prevent mechanical damage; the other is to protect the thermocouple from chemical corrosion of the measured medium and the harmful effects of oxidizing or reducing atmospheres.
Therefore, when selecting materials, we should consider the material's: high temperature resistance, mechanical strength, thermal conductivity, etc.
Metal protection tubes: high mechanical strength, good thermal conductivity, and very wide application. However, the high temperature resistance is not good enough and it is susceptible to corrosion. The details are as follows:
Material
Operating Temperature (°C)
Characteristics & Applications
Cr28
1100
Excellent corrosion and mechanical wear resistance, mainly used in sulfuric acid roasting furnaces.
Cr25-1120
1150
Good oxidation resistance, high cost, mainly used in high-temperature oxidation environments.
1Cr18Ni9Ti
800
High-temperature corrosion resistance, used as general heat-resistant steel.
304
800
Low carbon content, excellent intergranular corrosion resistance, commonly used as primary heat-resistant steel.
310S
1000
High-temperature oxidation resistance and corrosion resistance, commonly used as heat-resistant steel.
316
750
Low carbon content, good intergranular corrosion resistance, used as corrosion-resistant steel.
316L
750
Ultra-low carbon content, excellent intergranular corrosion resistance, used as corrosion-resistant steel.
H. Alloy-276
700
Excellent intergranular corrosion resistance, used as corrosion-resistant steel.
Inconel 600
1000
Nickel-chromium-iron alloy with excellent high-temperature oxidation resistance, used as heat-resistant steel.
Monel K500
700
Nickel-copper alloy with good intergranular corrosion resistance, suitable for strong sulfuric acid environments.
GH3030
1100
Nickel-based high-temperature alloy steel, excellent oxidation and corrosion resistance, commonly used as heat-resistant steel.
GH3039
1300
Nickel-based high-temperature alloy steel, superior oxidation and corrosion resistance, commonly used as heat-resistant steel.
Optional specifications and sizes of protective tube:
