Protection Sheath Material Ferrous

Materials specification for temperature sensor protection sheaths

Our temperature sensors are specifically designed for many different types of harsh and reducing atmosheres and therefore we supply protection sheaths suitable for each application. Here is a list of datasheets for the materials that we supply and use. This list is available as a PDF. Click on the material names for more information.

Mild Steel
Ceramic support tube (Plated) Occasional sensor protection use

Basic Composition	Fe, C
Temperature Limits	550 ° C
International Standards	Seamless Pipe
Density	7.9 g/cm³
Melting Range
Specific Heat
Coefficient of Expansion
Thermal Conductivity
Peak Sensors Colour Code	Black

446, 4C54, Ferritic
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
Melting Range
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

Kanthal AF, Kanthal APM
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	1400 ° C
International Standards
Density	7.1 g/cm³
Melting Range
Specific Heat
Coefficient of Expansion	12 rising to 16 x10^-6 / ° C
Thermal Conductivity	12 rising to 32 W/m ° C
Peak Sensors Colour Code

Kanthal Super
Less brittle than ceramics. Excellent in corrosive furnaces. Suppresses electromagnetic oscillations.

Basic Composition	Moloybdenum disilicade MoSi 2
Temperature Limits	1700 ° C
International Standards
Density
Melting Range
Specific Heat
Coefficient of Expansion
Thermal Conductivity
Peak Sensors Colour Code

Cast Iron
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
International Standards
Density	7.9 g/cm³
Melting Range
Specific Heat
Coefficient of Expansion
Thermal Conductivity
Peak Sensors Colour Code

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Mild Steel	4C54, Ferritic, 446 SS	Platinum Grain Stabilised
321 SS	Sanicro 31 HT®	Hastelloy C276
310 SS	Alloy 600 (Inconel®)	Kanthal AF, Kanthal APM
316 SS	Alloy 800 HT (Incoloy®)	Recrystalised Alumina (Alsint)
353 MA®	Platinum 10% Rhodium	Aluminous Porcelain (Pythagoras)
253 MA®	Kanthal Super	Silicon Carbide (Clay Bonded)
Pyrosil	Sillimanite 60	Silicon Carbide (Recrystalised)
Platinum	Quartz	Monel 400
Cast Iron	Brass	Hastelloy B2
Syalon 101	Platinum 10% Rhodium Grain Stabilised

Protection Sheath Material Datasheets

Materials specification for temperature sensor protection sheaths