The stainless steel flange heating tube consists of hairpin-bent tubular heating elements TIG-welded into an ANSI or DIN standard metal flange. It mounts directly through a matching tank nozzle or wall for direct immersion heating of liquids, viscous mediums, and gases in closed-loop industrial processes.
Design Features
Direct Immersion Geometry: Elements positioned inside the fluid mass maximize thermal energy transfer efficiency with minimal radiation loss.
Flange Integration: Bolt-on mounting allows straightforward removal for descaling, routine maintenance, and element replacement.
Terminal Enclosure Protection: NEMA 4/IP65 or explosion-proof housings shield electrical terminations from ambient moisture, corrosive vapor, and washdown environments.
Optimized Element Spacing: Calculated clearances between hairpin bends prevent localized overheating and promote thermal convection currents.
Technical Specifications
|
Technical Parameter |
Specification Range / Standard |
|
Flange Standards |
ANSI B16.5 (2" to 24", 150lb/300lb) / DIN EN 1092-1 (DN50 to DN500, PN10 to PN40) |
|
Sheath Materials |
SS304, SS316L, Incoloy 800, Titanium (for corrosive acid baths) |
|
Element Diameter |
8.0mm, 10.0mm, 12.0mm, 16.0mm |
|
Voltage Range |
200V - 600V (Single-phase or 3-phase) |
|
Watt Density Range |
2.5 W/cm2 to 12 W/cm2 (fluid-dependent) |
|
Max Operating Temperature |
Up to 650°C (sheath alloy-dependent) |
|
Insulation Material |
High-purity fused magnesium oxide (MgO) powder (>= 99.4%) |
Product Design & Structure
Resistance Wire: 80/20 Nickel-Chromium wire wound to precise resistance tolerances for uniform thermal output.
Die-Compacted Core: MgO powder is roller-compacted around the coil to maximize dielectric strength and eliminate internal air voids.
Weld Integrity: Automatic TIG welding joins the tubular elements to the flange base, pressure-tested to withstand specified system loads.
Cold Pin Section: Unheated terminal zones prevent overheating of terminal block connections inside the electrical enclosure.
Heating Performance
Direct fluid contact achieves thermal transfer efficiencies exceeding 98%.
Surface watt density parameters calibrated strictly against fluid viscosity to prevent fluid coking or localized film boiling.
Dynamic thermal response managed via standard SCR or PID control loops.
Applications
Water & Aqueous Solutions: Process water tanks, rinse tanks, industrial washing machines, deionized water loops.
Petrochemical & Lubrication: Heavy fuel oil preheating, lube oil reservoirs, asphalt heating tanks.
Chemical Processing: Mild acid plating baths, caustic solution tanks, chemical reaction vessels.
Pressurized Systems: Closed-loop heat transfer fluid skids, steam boilers, pressurized gas preheaters.
Customization Options
Flange Specs: Custom bolt hole patterns, non-standard dimensions, ASME Section VIII code stamp compliance.
Built-In Sensors: Integrated Thermocouple (Type K/J) or RTD (Pt100) thermowells positioned within the element bundle for direct process temperature monitoring.
Surface Treatments: Electropolished sheath surfaces, PTFE coatings, or anti-scaling passivation treatments.
Enclosure Types: Weatherproof, water-resistant, or hazardous-location certified terminal housings.
Manufacturing Process
Tube Inspection: Seamless or welded stainless steel tubes undergo dimensional and eddy-current integrity checks.
Coiling & Insertion: NiCr wire is coiled, centered with terminal pins, and inserted into the tube.
Powder Filling: High-purity MgO is vibratory-filled into the assembly to ensure uniform density.
Reduction: Rolling mills reduce tube diameter, compressing the MgO insulation to solid state.
Annealing & Bending: Controlled-atmosphere furnace annealing relieves stress prior to precise CNC hairpin bending.
Welding & Assembly: Elements are TIG-welded to the flange base and sealed with high-temperature silicone or ceramic end-seals.
Quality Control
Hydrostatic Pressure Testing: Each flange assembly is pressurized with water or pneumatic test rigs to verify weld and seam integrity.
Insulation Resistance (IR): Tested at 500V/1000V DC to ensure cold insulation resistance exceeds 1000 MΩ.
Dielectric Strength Test: Withstands 1800V AC dielectric breakdown voltage test for 1 minute without flashover.
Dimensional Verification: Laser and caliper verification of immersion length, flange thickness, and bolt circle diameter against approved engineering drawings.
FAQ
Q: How do I select the correct watt density for my fluid?
A: Watt density depends on specific heat and thermal conductivity. Water allows up to 8 W/cm2, while viscous oils require lower limits (1.5 to 3 W/cm2) to prevent surface coking and element burnout.
Q: What is the difference between SS304, SS316L, and Incoloy 800 sheaths?
A: SS304 suits clean water and non-corrosive fluids. SS316L contains molybdenum for chloride pitting and mild acid resistance. Incoloy 800 provides high-temperature creep and oxidation resistance for air and hot gases.
Q: Can these flange heaters be repaired if a single element fails?
A: Standard multi-element flange heaters with individually bolted or wired hairpin loops allow isolated loop replacement. Fully welded bundles typically require complete unit replacement.
Q: Do you provide ASME pressure vessel compliance or other certifications?
A: Flanges can be manufactured per ASME B16.5 standards, with optional Material Test Reports and third-party inspection reports available.
Q: What temperature control accessories are required for safe operation?
A: Units must pair with an independent high-limit temperature control sensor and a liquid-level interlock to prevent dry-firing when fluid drops below the heated zone.
Q: What is the standard lead time for custom-engineered flange heaters?
A: Standard configurations ship within 2 to 3 weeks. Custom designs requiring specialized flange ratings, specific alloy materials, or code compliance inspections require 4 to 6 weeks.
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