Tubular heaters can be formed for air, surface and liquid heating, but a drawing alone is not enough. The medium, sheath, bend sequence, cold ends and support arrangement need to be reviewed as one assembly.
Use this guide to prepare a design review or RFQ. Final ratings depend on the complete product, installation, controls and operating environment.
Selection inputs that change the design
| Decision | Information to provide | Why it matters |
|---|---|---|
| Heating medium | Air, liquid, contact surface or radiant space | Controls heat-transfer rate and allowable sheath loading. |
| Sheath | Stainless steel, nickel alloy or application-specific material | Must suit temperature and corrosion exposure. |
| Formed shape | Centerline dimensions, bend radius and terminal direction | Determines manufacturability and installation clearance. |
| Support | Mounting brackets, fittings and expansion allowance | Prevents vibration while allowing thermal growth. |
Define the thermal environment
State what the element heats, the medium temperature and target process temperature. Air removes heat less effectively than flowing liquid.
For surface contact, identify clamping and contact area. For radiant use, provide spacing, reflector and guard details.
Design a manufacturable form
Dimension from tube centerlines and show terminal orientation, cold lengths and fittings. Tight consecutive bends can conflict with internal construction.
Ask the manufacturer to confirm minimum bend radius and bend sequence. Do not field-bend a finished element unless supplied for that purpose.
Control temperature and expansion
Support long elements against vibration and sagging without locking every point. The assembly needs room to expand.
Use process control plus an independent high limit when loss of airflow, liquid level or contact could cause unsafe sheath temperature.
Common specification mistakes
- Selecting wattage without naming the medium
- Using an incompatible sheath
- Dimensioning outside of bends instead of centerlines
- Rigidly clamping every support
RFQ checklist
- Medium, flow and operating temperatures
- Voltage, phase, wattage and current
- Tube diameter, centerline drawing and radius
- Sheath, fittings and terminal enclosure
- Control sensor and over-temperature protection
Review the matching Tubular Heaters product range, then send this checklist with your drawing for an engineer-reviewed quotation.
Frequently asked questions
What sets minimum bend radius?
Tube diameter, sheath, internal construction and process all matter. Confirm it before finalizing the mount.
Can one design work in air and liquid?
A liquid-rated configuration may run too hot in air. Review every possible operating condition.
Where should the sensor go?
Place it where it represents the process and can detect loss of heat transfer.