DN40/DN50 Screw Plug Thermal Oil Immersion Heater
The Oil Heating Screw Plug Tube is a compact, high-efficiency immersion heating element engineered specifically for closed-loop thermal fluid systems, industrial oil baths, and hydraulic machinery. Unlike standard water heating elements that risk severe carbonization when immersed in viscous fluids, this unit utilizes an anti-coking low watt density design to ensure stable heat transfer without overheating the medium.
Constructed with heavy-duty SUS304/SUS316L stainless steel tubing and high-purity MGO insulation, our threaded immersion heaters are built for demanding industrial environments operating up to 300°C. Manufactured directly at our 5,000 m² Jin Dian facility in Jiaxing, every heater is rigorously pressure-tested and inspected under ISO 9001 quality management standards.
Technical Specifications
| Heating Medium / Application | Max Bulk Temp (°C) | Recommended Surface Load | Sheath Material |
| Mineral Thermal Fluid | 280°C – 300°C | 1.8 – 2.2 W/cm² | SUS304 / SUS316L |
| Synthetic Thermal Oil | 300°C – 320°C | 2.0 – 2.5 W/cm² | Heavy SUS316L |
| Hydraulic & Lube Oil | 80°C – 120°C | 1.2 – 1.5 W/cm² | Heavy SUS304 |
| Tap Water / Process Water | 100°C | 6.0 – 8.0 W/cm² | SUS304 / Copper |
Core Design Advantages
Anti-Coking Watt Load Engineering
Maintains surface watt densities below 2.5 W/cm² to avoid thermal cracking of thermal oil, drastically reducing carbon deposits on tube surfaces.
Heavy-Wall SUS304/SUS316L Tubing
Uses 1.0mm thick wall tubing compared to 0.65mm industry standard options, providing structural rigidity under dynamic fluid pressures.
Leak-Proof TIG Welding
Precision TIG welded or silver-brazed tube-to-plug joints prevent fluid ingress into the wiring terminals.
Extended Unheated Cold Zone
Integrated cold regions (50mm–100mm) safeguard against dry heating at mounting bosses when liquid levels drop.
Temperature Control Integration
Thermocouple Pocket (Thermowell)
Built-in internal thermowell tube accommodating K-Type, J-Type thermocouples, or PT100 RTD sensors for precise core temperature monitoring.
Capillary Thermostat Enclosure
Pre-mounted dial thermostat (0–300°C) inside the terminal box for standalone temperature limiting.
Explosion-Proof Terminal Enclosures
Optional cast-aluminum junction boxes certified for hazardous chemical or refinery environments.
Certificates
Material Spectrometry: X-ray spectrometer testing ensures raw tube material conforms strictly to SUS304/SUS316L chemical compositions.
Dielectric Withstand Test: 100% flash tested at 1800V AC for 1 second to eliminate short-circuit risks.
Pressure Sealing Test: Pneumatic pressure testing at 1.5 MPa ensures complete joint integrity.
FAQ
Q: What causes carbon buildup on immersion heating elements in oil tanks?
A: Carbon buildup occurs when the surface temperature of the element sheath exceeds the thermal cracking threshold of the fluid. Fluid localized at the tube surface breaks down, leaving a crusty layer of carbon. Over time, this carbon acts as thermal insulation, causing heat to build up inside the tube until the internal nickel-chromium wire melts. Maintaining surface load densities under 2.5 W/cm² prevents this issue.
Q: How do I accurately measure the thread size on my existing heater for replacement?
A: Thread sizes can be confirmed by measuring the outer diameter of the male plug threads with a caliper. A DN40 (1.5" G) thread measures approximately 47.8mm outer diameter, while a DN50 (2" G) thread measures roughly 59.6mm outer diameter. Always verify thread pitch and gasket seat profile before ordering replacements.
Q: Why is an unheated cold zone necessary for industrial immersion heaters?
A: An unheated cold zone ensures that the active heating length remains entirely submerged below the dynamic minimum liquid level. If a heating area is exposed to air during fluid movement or evaporation, dry heating occurs, leading to localized burnout and potential safety hazards.
Q: Can 380V 3-phase screw plug heaters be operated on a 220V power supply?
A: A 380V heater can physically be connected to 220V, but the heat output drops significantly to approximately 1/3 of its rated wattage (P = U² / R). For proper heating performance, elements should always be wired according to their design voltage and phase configuration.
Hot Tags: oil heating screw plug tube, China oil heating screw plug tube manufacturers, suppliers, factory