Sheathed Electric Heater
Analysis completed, with reference to 9 sources
Sheathed electric heaters (also known as armored heaters, MI mineral-insulated heating elements) represent a high-end form in the industrial heating field. Their core lies in the "core wire-insulation-sheath" three-layer coaxial hermetically sealed structure, offering significant advantages such as high temperature resistance, corrosion resistance, bendability, and vacuum compatibility. They are widely used in demanding conditions in semiconductors, chemicals, new energy, aerospace, and other industries. Based on your procurement needs, here are the core selection points and references for local and surrounding manufacturers:
Core Selection Parameters
During selection, the following parameters must be carefully matched to ensure heating efficiency and service life:
Structure and Form:
Rigid sheathed heating rods: Diameter typically 3-30mm, length customizable, suitable for fixed-point heating scenarios such as reactors, molds, and vacuum furnaces.
Flexible MI heating cables: Diameter typically 1-6mm, can be bent arbitrarily like cables, with a minimum bending radius of about 4-6 times the cable diameter, suitable for pipeline tracing, complex cavity heating, and other scenarios.
Formed parts: Can be processed into spiral, U-shaped, ring-shaped, flanged, and other special-shaped structures to fit special installation spaces.
Material Selection (Three-Layer Structure):
Heating core wire: Nickel-chromium alloy (Cr20Ni80, suitable for ≤1000°C), iron-chromium-aluminum alloy (FeCrAl, suitable for ≤1300°C), molybdenum-based/platinum-based alloys (suitable for 1200-2000°C, requiring vacuum or inert atmosphere).
Insulation layer: High-purity magnesium oxide (MgO, mainstream choice), aluminum oxide (Al₂O₃, higher temperature resistance, used in vacuum scenarios), zirconium oxide (ZrO₂), etc.
Metal sheath: 304/316L stainless steel (conventional corrosive environments, ≤650°C), Incoloy 800/840 (high-temperature oxidation resistance, ≤800°C), titanium alloy/Hastelloy (strongly corrosive environments), copper/copper-nickel alloy (tracing scenarios, ≤300-450°C).
Power and Surface Load:
Tracing-type MI cables: Power density 5-50W/m, used for pipeline insulation and anti-condensation.
Heating rod type: Power density 50-500W/m, used for liquid/gas heating.
High power density scenarios: Semiconductor wafer heating plates, etc., can reach over 20W/cm².
During selection, theoretical power must be calculated based on the medium's specific heat capacity, mass, temperature difference, and heating time, with a 10%-30% margin reserved.
Temperature Resistance and Insulation Performance:
Continuous operating temperature covers 50°C to over 2000°C; actual operating temperature is recommended to be controlled within 80% of the rated temperature resistance.
Room-temperature insulation resistance ≥100-1000MΩ, high-temperature ≥10MΩ, with excellent withstand voltage performance.
Electrical Parameters:
Voltage supports multiple specifications such as 24V, 36V, 110V, 220V, 380V, with 220V/380V mainly used in industrial scenarios.
When multiple groups are connected in parallel, attention must be paid to three-phase load balance.
Safety and Protection:
Explosion-proof occasions require explosion-proof certificates (such as Exd II CT4), with supporting temperature control systems for multiple protections including over-temperature and low liquid level.
Vacuum scenarios must meet extremely low outgassing rates (<10⁻⁹ Torr·L/s·cm²) and pass helium leak testing.
References for Local and Surrounding Manufacturers
Jiangsu is the core industrial belt for electric heating equipment in China. Yangzhou and its surrounding areas have multiple professional manufacturers of sheathed heaters, facilitating on-site inspections and after-sales support:
Yangzhou Local:
A leading enterprise in China for sheathed MI mineral-insulated heating cables and explosion-proof electric tracing systems. Products cover sheathed heaters, MI heating cables, vacuum heating elements, semiconductor wafer heating plates, etc. Explosion-proof rating reaches Exd II CT4, widely used in photovoltaic/photo-thermal, semiconductor equipment, new energy batteries, plastic machinery, and other industries, having served well-known equipment manufacturers such as Suzhou Maxwell and Jiejia Weichuang.
Produces stainless steel sheathed electric heaters, operating temperature ≤500°C, sheath material options include 304/316L/310S stainless steel, cold-state insulation resistance >300MΩ, tube diameter coverage from Φ3.5mm to Φ30mm, supporting customization.
(Jiangdu District): Focused on R&D and manufacturing of high-power, high-temperature 900°C explosion-proof electric heating equipment, can customize TFE, HFP cracking furnace and other special sheathed heating equipment, with a single unit maximum of 6000kW.
Baoying County): Deeply engaged in the field of explosion-proof electric heating for hazardous media such as petroleum, chemicals, and natural gas, using MI heating cables as heating elements, with products covering tens of thousands of electric heating equipment sets.
(Baoying County): High-tech enterprise, business scope includes design, manufacturing, and sales of explosion-proof electric heating systems and electric tracing systems, with 94 patent information items.
Business scope includes R&D, processing, and sales of electric heating tubes and electric heaters, manufacturing of explosion-proof electric heaters and temperature control equipment, supporting non-standard customization.
Surrounding Areas:
Sheathed MI tracing cables, stainless steel/copper sheath optional, power 50-150W/m, length 3-120m), (CEMS sampling tracing pipelines, sheathed MI heating cables).
(Sheathed MI heating cables, stainless steel/copper-nickel/copper sheath optional, maximum temperature resistance 650°C, power up to 269W/m).
Others: Chunhui Instruments (sheathed heaters, covering multiple temperature zones from 50°C-1500°C, supporting customized adjustment of sheath materials and sealing processes).
Selection Precautions
Clarify heating medium and temperature: Different media (water/oil/acid-base/air/vacuum) have greatly differing requirements for sheath material and surface load. Working conditions must be confirmed before selection.
Reserve margin in power calculation: Calculate theoretical power according to the formula P=(m×c×ΔT)/(t×η)+P dissipation, and add a 1.2-1.5 times safety factor during actual selection.
Explosion-proof compliance: Products with explosion-proof certificates must be selected for flammable and explosive environments, and the explosion-proof rating must match the on-site hazardous area classification.
Installation and wiring specifications: The bending radius of flexible MI cables shall not be less than 4-6 times the cable diameter; the sheathed layer must be reliably grounded (grounding resistance ≤4Ω), away from strong electromagnetic interference sources.
