Careers High Emissivity Coatings for New Stainless Steel Process Tubes
Achieve Full Heater Performance From Startup
New stainless steel process tubes in fired heaters can have surface emissivity of only 0.35–0.40 at startup. IGS applies a thin-film high emissivity ceramic coating before startup, enabling fired heaters to achieve design thermal performance without waiting for a natural oxide layer to develop.
New Stainless Steel Tubes Initially Reduce Radiant Heat Transfer
Carbon and low-alloy steel process tubes operating at elevated temperatures quickly develop an oxide layer with high surface emissivity, allowing efficient absorption of radiant energy.
Newly installed stainless steel process tubes typically have a polished metallic surface with emissivity of approximately 0.35-0.40. A metallurgy upgrade is often intended to allow higher heat flux, such as for increased throughput or process severity. However, the heater may not realize the full benefit of the new material immediately after startup. Until a stable oxide layer develops, which may take several months to years, radiant heat absorption is reduced, shifting more furnace duty to the convection section.
This temporary reduction in emissivity can result in:
- Higher bridgewall temperatures
- Reduced radiant heat absorption
- Excess heat transfer to the convection section
- Potential convection section limitations that may reduce production or cause excessive fouling
- Reduced operating margin during startup
- Delayed achievement of optimum heater performance
Natural oxidation eventually restores emissivity, but the process may take several months to years, depending on operating conditions.
The Solution
Restore High Emissivity Before Startup
IGS applies a thin-film ceramic coating before startup, increasing surface emissivity from approximately 0.35-0.40 to 0.90.
By restoring radiant heat absorption before startup, radiant heat transfer is optimized from day one, eliminating the temporary performance loss associated with uncoated stainless steel tubes.
The coating can be applied in a fabrication shop or in situ, depending on project requirements. The latest coating technology requires no separate thermal curing before startup, reducing application time, simplifying logistics, and lowering project costs. Final curing occurs during initial startup.
Benefits of Coating New Stainless Steel Process Tubes
- Full operating capability from startup
- Lower bridgewall temperatures
- Increased radiant heat absorption
- More efficient radiant heat transfer
- No pre-startup thermal curing required
- Reduced project time and cost
- Shop or in situ application
Looking to Improve the Performance of Existing Process Tubes?
For fired heaters already in service, Cetek® High Emissivity Coatings improve thermal efficiency, reduce oxidation and carburization, extend tube life, and lower fuel consumption.
Measured Performance on New 317H Stainless Steel Process Tubes
A North American refinery coated new 317H stainless steel process tubes before installation during a planned fired heater retube.
Eight months of operating data demonstrated significantly improved thermal performance compared with engineering calculations for identical uncoated stainless steel tubes.
| Metric | Result |
|---|---|
| Tube surface emissivity | 0.35–0.40 → 0.90 |
| Bridgewall temperature | 111–113°C (200–203°F) lower |
| Additional radiant energy absorbed | 2.44–2.60 MW |
| Heater operation | Immediate full-rate capability |
Based on eight months of measured operating data compared with engineering calculations for identical uncoated tubes.
Read the full case study
Why Lower Bridgewall Temperatures Matter
Increasing radiant heat absorption reduces bridgewall temperatures by keeping more heat within the radiant section, limiting thermal exposure of downstream components such as convection tubes, tube supports, and associated internals, and helping to avoid convection section limitations.
Planning a Stainless Steel Retube?
Speak with an IGS specialist to determine whether high emissivity coatings are suitable for your fired heater retube.
Frequently Asked Questions About Coating New Stainless Steel Tubes
→ Why do new stainless steel tubes reduce heater performance?
New stainless steel process tubes have a polished metallic surface with low emissivity, typically 0.35-0.40, which reduces their ability to absorb radiant heat. Until a stable oxide layer develops during operation, more heat is transferred to the convection section, resulting in higher bridgewall temperatures and temporarily reduced radiant heat absorption.
→ What does the coating do?
The coating increases surface emissivity from approximately 0.35-0.40 to 0.90, restoring efficient radiant heat absorption from startup.
→ Does the coating provide corrosion protection?
No. Stainless steel process tubes already provide corrosion resistance. The coating is applied to maximize radiant heat absorption and eliminate the temporary performance loss associated with low-emissivity tube surfaces.
→ Can the coating be applied before installation or in situ?
Yes. The coating can be applied in a fabrication shop prior to shipment, in a laydown yard before installation, or in situ during planned maintenance outages, depending on the project requirements and site conditions.
→ Does the coating require thermal curing before startup?
No. The latest generation of the coating initially cures through a chemical process and does not require separate thermal curing before startup. This reduces application time, simplifies logistics, and lowers overall project costs. Final curing occurs during initial startup, following the gradual temperature ramp-up specified in the operating manuals. After curing, the coating provides strong resistance to high-pressure moisture, thermal cycling, and steam.
→ What performance improvements can be expected?
Performance improvements depend on the fired heater design and operating conditions. In one refinery application, coating new stainless steel process tubes reduced bridgewall temperatures by 111–113°C (200–203°F) and increased radiant energy absorbed by the process tubes by 2.44-2.60 MW, enabling immediate full-rate operation following startup.
Ready to Achieve Full Heater Performance From Startup?
Speak with an IGS specialist to determine whether high emissivity coatings are suitable for your new stainless steel process tubes.