B - Temperatur-Shop

Technical Notes Straight Thermocouples in general
Reference values for the use of metallic materials for protection tubes
Max. air temperature
°C
Material Resistance in atmosphere Nitrogenous
poor in oxygen
Oxydating Reducing
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Carburization
550 St 35.8 (1.0305) poor poor good ------
850 X10CrAI18 (1.4571) excellent good poor good
1200 X10CrAI24 (1.4762) excellent very good poor good
1200 X15CrNiSi2520 (1.4841) poor poor very good poor
1200 X15NiCr6015 (1.4867) poor poor very good poor
Tempering Furnaces St 35.8 (1.0305)
Casehardening and
heating furnaces
Oxidising atmosphere, sulfurous and carbonic: X10CrAI18 (1.47452) und X10CrAI24 (1.4762)
Chemically aggressive steam: X10CrNiTi189 (1.4541) oder X10CrNiMoTi1810 (1.4571)
Nitration furnaces Atmosphere nitrogenous, poor in oxygen: X15CrNiSi2520 (1.4841)
Salt melting Salpeter up to 550 °C Pure iron M2 M2
Cyan up to 950 °C Pure iron M2 M2
Chloride 600 up to 1050 °C X10CrAI24 (1.4762)
Metal smelting Aluminium, Magnesium up to 700 °C GG-22 (0.6022)
Aluminium with magnesium up to 700 °C Pure iron M2 M2
Bearing Metal up to 600 °C St 35.8 (1.0305), emailliert
Lead up to 600 °C St 35.8 (1.0305) oder GG-22 (0.6022)
Zinc up to 480 °C St 35.8 (1.0305), emailliert
up to 600 °C Pure iron M2 M2
Tin up to 600 °C St 35.8 (1.0305), emailliert
Copper up to 1250 °C X10CrAI24 (1.4762)
Brass up to 900 °C X10CrAI24 (1.4762)
As the applications and operating conditions vary, these specifications are only reference values.
Protective arrangements: The life time of the protection tubes made of carbon steel can be prolonged by coating a vitreous-enamelling or by a protective coating. As melting attacks
the surface the most, the tubes can be protected by repeated changes of the immersion depth, by a muffle or a bandage made of glass fibre ribbon with water glass.
Reference values for the use of ceramic protection tubes
Pythagoras Type C 610* All gases, free from hydrofluoric acid and alkalic steams up to 1500 °C
Alsint 99,7 Type C799* Alkali steams (glass melting and stoneware furnace) up to 1600 °C
Glass melting up to 1500 °C
Sillimantin 60 Type C 530* All gases, if a gastight ceramic inner tube is used up to 1600 °C
The resistance to sudden changes of temperature of ceramic tubes impermeable to gas, like type C610 and type C799, is good. At high temperatures a vertical installation is
required due to the poor rigidity.
Resistance to sudden
temperature changes
Density Permanent temperature permitted
Pythagoras Type C 610* good impermeable to gas 1500 °C
Alsint 99,7 Type C799* good impermeable to gas 1600 °C
Sillimantin 60 Type C 530* very good porous 1600 °C
* Type C 799, type C 610 and type C 530 stand for the former DIN specifications Ker 710, Ker 610 und Ker 530
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