Selection of threaded flange electric heating tubes focuses on matching the medium, accurately calculating power, choosing the correct material and dimensions, and controlling power density, with priority given to small-power liquid heating applications.
1. Clarify the usage scenarios and media
The threaded flange type is suitable for low-power liquid heating (water, oil, thermal oil, etc.), with a recommended power limit of ≤18KW; for high-power applications, the flat flange type is preferred.
• Water/Weak Corrosive Liquids: Prefer 316L (resistant to chloride ions), tap water/soft water can use 304.
• Oil/Heat transfer oil: 304/321, high-temperature oil options include 310S or Inconel 800.
• Corrosive media: 316L stainless steel, titanium tubes, Hastelloy (customized according to corrosive media).
• Dry burn/air: Not recommended for threaded flanges; if necessary, select finned tubes and strictly control power density.
2. Calculation and Matching Power
•Experience Estimation
Water heating: 1:2 to 1:4 (Power KW: Heating zone length m), e.g., 2–4 KW for a 1m heating zone.
Oil heating: 1:1 (anti-coking, overheat protection), 1KW per 1m heating zone.
•Precise formula
P=m×c×ΔT3600×t×η
m: Medium mass (kg); c: Specific heat capacity (kJ/kg·°C); ΔT: Temperature rise (°C); t: Heating time (h); η: Thermal efficiency (0.7–0.9).
• Voltage matching: Commonly used at 220V/380V; high power applications prioritize 380V three-phase to reduce current and line loss.
3.Material Selection
|
Material |
Applicable Temperature |
Applicable Medium |
Features |
|
304 stainless steel |
≤600°C |
Water, neutral oil, air |
Universal and cost-effective |
|
316L stainless steel |
≤600°C |
containing Chlorine water, weak acids, seawater |
Corrosion resistant, long service life |
|
310S/Ni 800 |
≤1000°C |
High temperature oil, dry burning, corrosive gases |
High temperature resistance, oxidation resistance |
• Thread/Flange Material: Same as heating tube or 304/brass, ensuring strength and sealing.
• Internal heating elements: 0Cr25Al5, Cr20Ni80, Kanthal, etc., matched to surface temperature.
4. Dimensions and Installation
• Thread specifications (commonly used): DN25 (1 inch), DN40 (1.5 inch), DN50 (2 inch), matching container interfaces.
• Pipe diameter: φ8–20mm, commonly used φ10/12/14/16mm; the larger the diameter, the lower the power density and the longer the lifespan.
• Heating zone length: Customized according to container depth and immersion requirements to ensure complete liquid immersion.
• Flange/thread: Hex flange facilitates installation and disassembly; thread type is pipe thread (G/R), ensuring reliable sealing.
5. Control power density
• Water heating: 3–8 W/cm².
• Oil heating: 1–3 W/cm² (to prevent carbonization and localized overheating).
• Dry burn/air: 0.5–2 W/cm² (fins can reach 3–5 W/cm²).
• Principle: The lower the power density, the longer the lifespan; exceeding the upper limit can lead to ablation, scaling, and leakage.
6. Other Key Parameters
• Pressure resistance: Liquid heating ≥0.6MPa, select according to container pressure.
• Insulation: Normal state ≥100MΩ, humid state ≥50MΩ (500V megohmmeter).
• Explosion-proof: Select explosion-proof types for flammable and explosive environments, complying with GB3836.
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Post time: Mar-19-2026
