Protection Sheath Material Datasheets

Very good resistance to oxidation, combustion gases and carburisation.

Basic Composition: Cr 21%, Ni 11%, Si 1.7%, Mn 0.8% Max, N 0.17%, C 0.08, P 0.04, S 0.03, Ce 0.05, Bal Fe
Temperature Limits: 1150 ° C Max in Air, oxidation and carburisation.
International Standards: 1.4835, S 30815, W Nr 1.4893
Density: 7.8 g/cm³
Specific Heat: 440 rising to 690 J/Kg ° C
Coefficient of Expansion: 16 rising to 24 x10-6 / ° C
Thermal Conductivity: 14.5 rising to 29 W/m ° C
Peak Sensors Colour Code: Pink

Commonly called 25/20. Good oxidation resistance and resistant to sulphur and reducing atmospheres. High temperature sheathing. Carbon dioxide to 900 ° C. Continuous operation in air up to 1150 ° C, without temperature variation. Not recommended for use continuously between 550 ° C and 850 ° C.

Basic Composition: Cr 25%, Ni 20%, Mn 2%, Si 2%, C 0.02%, Bal Fe.
Temperature Limits: 1100 ° C
International Standards: BS 970 Grade 310 S31, W No 1.4841
Density: 7.9 g/cm³
Melting Range: Approx 1400 ° C
Specific Heat: 500 J/Kg ° C
Coefficient of Expansion: 16.5 x10-6 / ° C
Thermal Conductivity: 14.7 W/m ° C
Peak Sensors Colour Code: Silver

Excellent corrosion and pitting resistance. Similar to 321 SS but with better acid resistance. Usually used in chemical plants and many other industrial applications.

Basic Composition: Cr 17.5%, Ni 12.5%, Mn 2%, Si 1%, Mo 2-2.5%, C 0.03%, Bal Fe.
Temperature Limits: 800 ° C
International Standards: BS 970 Grade 316, W No 1.4401
Density: 7.9 g/cm³
Melting Range: Approx 1400 ° C
Specific Heat: 500 J/Kg ° C
Coefficient of Expansion: 17 x10-6 / ° C
Thermal Conductivity: 14.7 W/m ° C
Peak Sensors Colour Code: Silver

Commonly called 18/8. Excellent corrosion resistance and remains ductile. Used for MI sheathing for type J and Pt 100’s. Withstands hot crude oil products, steam and combustion gases. Carbon dioxide to 650 ° C. Air up to 900 ° C without temperature variation.

Basic Composition: Cr 18%, Ni 9%, Mn 2%, Si 1%, C 0.1%, Bal Fe
Temperature Limits: 800 ° C
International Standards: BS 970 321 S31, W No 1.4541
Density: 7.9 g/cm³
Melting Range: Approx 1400 ° C
Specific Heat: 500 J/Kg ° C
Coefficient of Expansion: 17 x10-6 / ° C
Thermal Conductivity: 14.7 W/m ° C
Peak Sensors Colour Code: Silver

Very good resistance to oxidation, combustion gases and carburisation. Good resistance to nitriding gases. Excellent in petrochemical furnaces including cracked ammonia.

Basic Composition: Cr 25%, Ni 35%, Si 1.6%, Mn 1.5% Max, N 0.16%, C 0.05, P 0.04 Max, S 0.03 Max, Ce 0.05, Bal Fe
Temperature Limits: 1175 ° C
International Standards: UNS S 35315
Density: 7.89 g/cm³
Specific Heat: 450 rising to 670 J/Kg ° C
Coefficient of Expansion: 18.5 x10-6 / ° C
Thermal Conductivity: 11 rising to 28 W/m ° C

Very good resistance to sulphurous gases and salts. Good resistance to oxidation in air. Good resistance to oil ash corrosion, molten copper, lead, tin. In sulphurous reducing atmosphere 446 performs better than austenitic steels, although Nitrogen concentrations can result in early failure. Hot gases containing hydrocarbons and carbon monoxide can cause carburisation, if oxygen is present for an oxide layer to form 446 performs well, otherwise failure occurs quickly.

Basic Composition: Cr 26.5%, Mn 0.8%, Si 0.5%, N 0.2%, C 0.2% Max, P 0.03 Max, S 0.15 Max, Bal Fe
Temperature Limits: 1100 ° C in air and oxidising conditions
International Standards: 1.4749, 446-1
Density: 7.6 g/cm³
Specific Heat: 460 rising to 670 J/Kg ° C
Coefficient of Expansion: 13.5 x10-6 / ° C
Thermal Conductivity: 17 rising to 28 W/m ° C
Peak Sensors Colour Code: Blue

A strong oxidation resistant material at high temperatures, particularly with cycling. Good resistance to carburisation. Resists sulphur compounds and carbon dioxide to moderate temperatures only. Excellent neutral and alkaline salt bath resistance Good in many acid salt baths. Good for nitriding atmospheres.

Basic Composition: Ni 72% Min, Cr 14-17%, Fe 6-10%.
Temperature Limits: 1100 ° C
International Standards: W No 2.4816, UNS N06600
Density: 8.472 g/cm³
Melting Range: 1354 to 1413 ° C
Specific Heat: 444 J/Kg ° C
Coefficient of Expansion: 10 rising to 16 x10-6 / ° C
Thermal Conductivity: 15 rising to 27 W/m ° C
Peak Sensors Colour Code: Red

Resistance to high temperature corrosion. Excellent oxidation and carburisation resistance. Reasonable sulphur resistance at moderate temperatures Alloy 800 and Alloy 800 H are very similar but they have lower creep rupture strength at temperature.

Basic Composition: Ni 30-35%, Cr 19-23%, Fe 39.5% Max,
Temperature Limits: 1100 ° C
International Standards: W No 1.4876, UNS N08811
Density: 7.945 g/cm³
Melting Range: 1357 to 1385 ° C
Specific Heat: 460 J/Kg ° C
Coefficient of Expansion: 14 rising to 18 x10-6 / ° C
Thermal Conductivity: 11 rising to 32 W/m ° C

Good thermal shock resistance. Used with J, K, N and E conductors.

Basic Composition: Al 2O 3 60%
Temperature Limits: 1500 ° C
International Standards: DIN VDE 0335 C610
Density: 2.6 g/cm³
Coefficient of Expansion: 6 x10-6 / ° C
Thermal Conductivity: 2 W/m ° C

Inexpensive engineering material. Easily machined to complex shapes. Readily available. Becomes brittle with heat.

Basic Composition: Cu 85%, Zn 15%.
Density: 8.8 g/cm³
Thermal Conductivity: High

Inexpensive material used in molten aluminium. It has a relatively short life due to oxidation but other materials also have their drawbacks in this application. Brittle metal.

Basic Composition: Fe, C (3 to 3.5%)
Temperature Limits: 900 ° C in Aluminium
Density: 7.9 g/cm³

Significant resistance to reducing environments, and many acids.

Basic Composition: Ni 68%, Mo 28%, Fe 2%, Co 1%, Cr 1%.
Temperature Limits: 815 ° C
International Standards: UNS 10665
Thermal Conductivity: High

Corrosion resistance in reducing and oxidising atmospheres. Severe environments. Maintains corrosion resistance after welding.

Basic Composition: Ni 57%, Mo 16%, Cr 15.5%, Fe 5.5%, W 3.8%
Temperature Limits: 1040 ° C
International Standards: UNS N10276
Density: 8.9g/cm³
Melting Range: 1325 – 1370 ° C
Coefficient of Expansion: 12.8 x10-6 / ° C
Thermal Conductivity: High

High resistance to attack by sulphur. Resists carburisation at temperature. Very little scaling reduces furnace contamination. Better heat transfer than ceramic.

Basic Composition: Cr 22%, Al 4-6%, Fe Balance.
Temperature Limits: 1300 ° C
Density: 7.1 g/cm³
Coefficient of Expansion: 12 rising to 16 x10-6 / ° C
Thermal Conductivity: 12 rising to 32 W/m ° C

Ceramic support tube (Plated) Occasional sensor protection use

Basic Composition: Fe, C
Temperature Limits: 550 ° C
International Standards: Seamless Pipe
Peak Sensors Colour Code: Black

Resists sea water, steam, salt and caustic solutions. Used in heat exchangers. Other Monel available.

Basic Composition: Ni 67%, Cu 28%, F3 3%, Mn 2%
Temperature Limits: 0 to 480 ° C
International Standards: UNS N00440
Density: 8.84g/cm³
Melting Range: 1320 ° C
Specific Heat: 430 J/Kg ° C
Coefficient of Expansion: 14 x10-6 / ° C

Direct contact with molten glass.

Basic Composition: Pt
Temperature Limits: Depends on expected lifetime
Density: 21.45 g/cm³
Melting Range: 1769 ° C
Coefficient of Expansion: 9.1 x10-6 / ° C
Thermal Conductivity: 74 W/m ° C at 20 ° C

Direct contact with molten glass, higher strength at elevated temperature .

Basic Composition: Pt 90%, Rh 10%
Temperature Limits: 1700 ° C
Density: 20.00 g/cm³
Melting Range: 1840 to 1870
Coefficient of Expansion: 8.6 x10-6 / ° C
Thermal Conductivity: 31 W/m ° C at 20 ° C

Direct contact with molten glass. As platinum 10% rhodium but with higher stress rupture strength and creep behaviour. Grain stabilisation reduces degradation at temperature and allows for a thinner wall.

Basic Composition: Pt 90%, Rh 10%
Temperature Limits: 1700 ° C
Density: 19.80 g/cm³
Melting Range: 1840 to 1870
Coefficient of Expansion: 8.6 x10-6 / ° C
Thermal Conductivity: 31 W/m ° C at 20 ° C

Direct contact with molten glass. As platinum but with higher stress rupture strength and creep behaviour. Grain stabilisation reduces degradation at temperature and allows for a thinner wall. Avoids rhodium inclusion which can discolour glass.

Basic Composition: Pt
Temperature Limits: 1700 ° C
Density: 21.45 g/cm³
Melting Range: 1769 ° C
Coefficient of Expansion: 9.1 x10-6 / ° C
Thermal Conductivity: 74 W/m ° C at 20 ° C

MI Thermocouple types K and N sheathing. Better oxidation resistance than Alloy 600 .

Basic Composition: Ni Cr Si
Temperature Limits: 1250 ° C

Low coefficient of expansion, High thermal shock resistance.

Basic Composition: SiO 2
Temperature Limits: 1500 ° C (Then flows under own weight)
Density: 2.2 g/cm³
Melting Range: 1683 ° C
Specific Heat: 670 J/Kg ° C
Coefficient of Expansion: 5.5 x10-7 / ° C
Thermal Conductivity: 1.4 W/m ° C

A pure and tough ceramic exhibiting hardness and vacuum tightness. Excellent in oxidising and reducing atmospheres. Fair thermal shock resistance. Used with R, S and B thermocouples.

Basic Composition: Al 2O 3 99.7%
Temperature Limits: 1750 ° C
International Standards: DIN VDE 0335 C799
Density: 3.9 g/cm³
Melting Range: 2072 ° C
Coefficient of Expansion: 8 x10-6 / ° C
Thermal Conductivity: 26 W/m ° C

Performs well in salt baths for heat treatment, cyanide or neutral salt baths.

Basic Composition: Cr 21%, Ni 31%, Si 0.6%, Mn 0.6%, Ti 0.5%, Al 0.5%, C 0.7, S 0.03, P 0.015 Max, S 0.01 Max, Bal Fe
Temperature Limits: 1100 ° C Max in air or oxidation gases
International Standards: N 08811/N08810, W Nr 1.4959 (W 1.4876)
Density: 7.9 g/cm³
Specific Heat: 460 rising to 680 J/Kg ° C
Coefficient of Expansion: 18.5 x10-6 / ° C
Thermal Conductivity: 11.6 rising to 31 W/m ° C

Excellent thermal shock resistance. Tends to have a thick wall to improve strength. A porous material that usually has a lining refractory for platinum sensors. High thermal conductivity. Not suitable for highly oxidising atmospheres.

Basic Composition: SiC 70 – 90 %
Temperature Limits: 1400 ° C
Density: 2.4 g/cm³
Coefficient of Expansion: 5.0 x10-6 / ° C
Thermal Conductivity: 28.0 W/m ° C

Excellent thermal shock resistance. A porous material that usually has a lining refractory for Platinum sensors. High thermal conductivity.

Basic Composition: SiC 99%
Temperature Limits: 1600 ° C in oxidising atmosphere, 2000 ° C in protected atmosphere
Density: 2.6 to 2.7 g/cm³
Coefficient of Expansion: 4.5 x10-6 / ° C
Thermal Conductivity: 30.0 W/m ° C

Very good thermal shock resistance. Porous.

Basic Composition: Al2O3 72 to 74%, SiO2 24-26%, Na2O & K2O 1%
Temperature Limits: 1350 ° C
International Standards: DIN EN 60672 Type C530
Density: 2.45 g/cm³
Coefficient of Expansion: 5.7 x10-6 / ° C
Thermal Conductivity: 1.4 W/m ° C

A strong and thermal shock resisting material for use in molten metals with little wetting or dross build up. Good in molten aluminium or salt baths. Fairly expensive.

Basic Composition: Silicon Nitride, Aluminium Oxide
Temperature Limits: 1000 ° C (1250 ° C in controlled conditions)
Density: 3.26 g/cm³
Coefficient of Expansion: 3.2 x10-6 / ° C
Thermal Conductivity: 16.7 W/m ° C