>> Tubular heating elements are the most versatile heat source. Tubular heaters are suitable for heating liquids, air, gases and solid bodies by conduction or radiation, they can be formed into an almost limitless variety of shapes.
We have supplied reliable tubular heating elements operating in excess up to ~ 850 degrees C. Our range includes standard sheath materials and diameters, together with a wide variety of fixing glands and electrical terminations. Cooling fins can be fitted if required and there are even versions for hazardous areas.
|Standardised options of tube diameter. Round or square tube|
|Tube material||Ø6,4||Ø8||Ø8,5||Ø9,60*||Ø10*||Ø10,92||Ø12||Ø12,5||Ø16||Class II Ø16||□6,1||□7,6||□9,65|
|Maximum tube length in mm|
|Tube protection||Seal||Seal temperature (base)|
|Maximumtemperature||Tube material||Type||Designation||Minimum temperature||Maximum temperature|
|Off||On||Under regular use||Under peak|
|175 °C||CopperAISI 304L or 321||E||Airtight||-40 °C||—||150 °C||170 °C|
|270 °C||covered by a tube of Teflón®||E||Airtight||-40 °C||—||150 °C||170 °C|
|300 °C||AISI 304L or 321||E||Airtight||-40 °C||—||150 °C||170 °C|
|300 °C||AISI 316L||E||Airtight||-40 °C||150 °C||170 °C|
|440 °C||Titanium||E||Airtight||-40 °C||—||150 °C||170 °C|
|500 °C||Steel||E||Airtight||-40 °C||—||150 °C||170 °C|
|600 °C||AISI 304L or 321||S||Extra Airtight||-40 °C||—||150 °C||170 °C|
|600 °C||AISI 316L||S||Extra Airtight||-40 °C||—||150 °C||170 °C|
|600 °C||Incoloy® 800 or 825||S||Extra Airtight||-40 °C||—||150 °C||170 °C|
|600 °C||AISI 304L or 321||H||Extra Airtight||-40 °C||—||250 °C||280 °C|
|600 °C||AISI 316L||H||Extra Airtight||-40 °C||—||250 °C||280 °C|
|600 °C||Incoloy® 800 or 825||H||Extra Airtight||-40 °C||—||250 °C||280 °C|
|700 °C||AISI 304L or 321||T||Porous||-40 °C||(*) 110 °C||200 °C||250 °C|
|750 °C||AISI 304L or 321||T||Porous||-40 °C||(*) 110 °C||200 °C||250 °C|
|850 °C||Incoloy® 800||T||Porous||-40 °C||(*) 110 °C||200 °C||250 °C|
|750 °C||AISI 304L or 321||C||Porous||-40 °C||(*) 110 °C||(**) 750 °C||(**) 750 °C|
|850 °C||Incoloy® 800||C||Porous||-40 °C||(*) 110 °C||(**) 850 °C||(**) 850 ° C|
(*) In porous seals, leaks may reach 5 mA per kilowatt during heating, however they remain within the limits of the values imposed by the norm when the regular working temperature is reached and as long as the temperature of the seal reaches a minimum of 110 ºC. For this reason we recommend that you do not opt for such a seal unless absolutely necessary due to the temperature that the seal or the tube will have to reach.
(**) The maximum temperature of the sealing coincides with the maximum temperature permitted in the tube sheath. Whatever, when installing, other temperature limitations should be kept in mind, such as the maximum temperature in the supply conductors, terminal pins, flanges, etc.
While designing the heater in which the resistors will be included, it has to be taken into account that the temperature reached by the resistors should not dangerously affect the other parts of the heater.
In order to ensure a reasonable life expectancy, you should check the capacity of the protecting material in resisting corrosion in the real conditions created by the machine in operation. We remind you that even stainless steel in drinking water may show signs of corrosion. For further information contact our technical-sales team!
A large number of connections can be provided – please contact us for further information.
For more information about our customer-specific solutions, please contact our technical sales department!
AISI 304L: Austenitic stainless steel. It presents optimum ability for soldering and good resistance to corrosion at room temperature. If it is kept for some time within the critical temperature interval of 450 to 850º, an inter-crystalline precipitation of chrome carbide may occur with the consequential inter-granular corrosion.
AISI 321: A specific amount of titanium is added to the components of the AISI304 with the effect of preventing formation of chrome carbide and, thus, preventing the phenomenon of inter-granular corrosion, making this material particularly suitable for use over prolonged periods of time at critical temperature interval. It has good resistance to formation of cinders up to 800ºC
AISI 316L: It contains an addition of 2÷3% molybden that gives it greater resistance to corrosion by pitting and better performance that the previous steels as far as low tension corrosion is concerned. Carbon content lower than 0.03% that makes it difficult for chrome carbide to form, thus increasing its resistance to inter-granular corrosion.
Incoloy® 800: Refractory stainless steel with high nickel and chrome content. Good resistance to formation of cinders up to 1,100ºC. It presents high resistance to tension and good resistance to corrosion at high temperatures.
Incoloy® 825: This is a nickel-iron-chrome alloy with additions of molybden and copper. It offers good resistance to both reducing and rusting acids, to corrosion due to tension, to pitting and to interstitial corrosion.
Copper (sf-cu din 1787): Semi-noble metal and by nature highly resistant to corrosion by water.
Titanium: Titanium is a metallic element that presents a compact hexagonal structure, it is hard, refractory and a good conductor of electricity and heat. It presents high resistance to corrosion. Resistance to corrosion that it presents is owing to the phenomenon of passivation that it undergoes (an oxide that coats it if formed)
Airtight seal: this seal does not allow moisture to enter the element, maintaining insulation values for more than five years. Sheath and seal temperature should not exceed 300ºC and 150ºC respectively. If the sheath temperature exceeds 300ºC or the seal temperature exceeds 150ºC, insulation values decrease rapidly and leaks appear within a short time.
Extra airtight seal: this seal does not allow the entry of moisture into the element either, maintaining the insulation values for more than ten years. In this case, temperature of the sheath can reach up to 600ºC. If the sheath temperature exceeds 600ºC or the seal temperature exceeds 150ºC/250ºC (according to thermic class), insulation values decrease rapidly and leaks appear within a short time.
Transpirable seal: When an element works at over 600ºC, it consumes oxygen. If the seal does not permit entry of such, the life of the element is reduced by about 100 hours. Thus, a seal has been designed to allow air to enter in sufficient quantities so as to permit correct respiration of the element. However, for proper respiration to occur, you should check that the element is halted for intervals of over 5 minutes, at least 15% of the time, and that it does not work without stopping for over 8 consecutive hours. Stoppages can easily be those originated by mediums of control, such as thermostats, etc. in the usual way in the majority of applications.
Due to the special conditions of this seal, on allowing the entry of air, it also allows moisture to enter, thus insulation can decrease to values of about 1 MΩ and, at the time of connecting, after a prolonged halt, transitory leaks of current may occur. These leaks may reach up to 5 mA per kilowatt during this period, then drop to values of 0.2 mA per kilowatt until the temperature is established. In order to ensure that the leaks disappear before temperature stabilization is reached, and thus comply with UNE-EN-60335 standards, it must be ensured that the seal temperature is at least 110ºC.