Damper Performance – Critical to every Heater/ Furnace

Safe operation of API 560 heaters is rooted in the maintaining of negative pressure (draft) internal to the heater. This draft works to draw in the correct amount of combustion air required to support the fluctuating combustion rates and corresponding production rates. While a heater’s draft capacity is set by the heater design, adjustment of that draft relies solely on performance of the heater dampers.


Responsive, Repeatable & Reliable damper operation is essential for automated combustion control systems and for the general wellbeing of the heater long term:

Improved Safety

Personnel near a heater are at increased risk whenever the heater interior achieves a positive pressure. Too little draft may result in not enough air being drawn in through the burners to achieve safe combustion. Exposure to leaking hot flue gases and even a heater deflagration event is possible from burner flame out & potential afterburning, resulting in severe burn injuries and possible fatalities.


Reduction of Heater Operational Rates (10% or more)

Too much draft will result in too much air being drawn in, the added volume in the air/ flue gas mixture resulting in the heater becoming draft limited, preventing the heater from firing at design capacity. Overall draft cannot be safely controlled by closing burner registers to restrict the air.

Violation of Heater Permit Emissions (5% or more)

A heater’s flue gas emissions is highly dependent upon the amount of excess air inside the heater firebox during operation. More fuel is burned to heat the excess air, resulting in increased NOx production with no benefit to the heater’s daily production.

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Reduction of Heater Efficiency (5% or more)

All excess air drawn into the heater will absorb heat, requiring additional heat (i.e., fuel) to achieve the needed process temperatures, a large portion of the heat literately going up & out the stack.

Progressive Heater Damage

Heat & Corrosion damage accelerates over time, requiring extensive repair or even heater replacement (refer to photos at right). Excessive draft draws cooling air into the firebox promoting H2S corrosion and causing the convection to be exposed to greater heat, damaging tubes, finning and supports. Positive pressure promotes flue gas leakage (bolted joints, observation doors, tube penetrations, etc.) causing distortion of the steel and refractory insulation failure.

For a more in depth explanation of our how to control excess air issues with our patented compensator solution, download our latest whitepaper here.

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Providing the Right Damper for your Heater

Birwelco USA (BUSA) provides custom damper solutions to meet the needs of existing heaters, air preheat & SCR systems, regardless of condition, age, or origin of manufacture. Every damper is designed to operate harmoniously with today’s control package requirements & capture proper ergonomics in manual override design, ensuring safe operation of the damper at all times. BUSA’s solutions address installation needs (online & offline), supplying dampers in assembly kits or complete flanged damper assemblies, minimizing the turnaround outage.

Responsive, Repeatable & Reliable (the BRRR Design)

BUSA’s damper designs directly address the design & performance issues typically experienced by existing fired heater/ furnace dampers:

Responsiveness – Dampers that open too fast are prone to mechanical failure and can create a pressure wave pulse internal to the heater, adversely impacting the burner operation. Immediate response at a controlled rate is best for heater performance.

Repeatability – Critical to the heater operation, the damper needs to steadily move to the required position, every time. Blade overshoot and the subsequent pull back always leaves the actual position of the blade in question.

Reliability – Unlike most dampers in service, BUSA’s damper designs utilize specialized actuators, linkages, bearings, seals, shafts & blades that are designed to be 100% removable for ease of inspection & proper maintenance, keeping the heater outage to a minimum.

Birwelco USA’s damper solutions have been developed in collaboration with REXA actuators, to find out more about this patented system click here

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Mechanical Design – BUSA’s BRRR damper design features:

Blades – Distributed reinforcement of damper blades, eliminating the heat warpage that turns flat damper blades into an ineffective “potato chip”.

Shafts – Solid stub shaft design provides optimal strength where needed to keep deflection and distortion in check. Pipe shafts distort in the heat over time, a leading cause for bound up dampers.

Seals – Proper bearing design working in harmony with the sealing system minimizes leakage, corrosion, and binding where the shafts come through the casing.

Control – Damper performance is always tied to the heater design. If controlling draft at reduced rates has historically been an issue, BUSA will utilize CFD Modelling to ensure the damper design provides the controllability necessary for safe operation at any firing rate.

Single Point Source for all your Fired Heater Needs

BUSA is an API Member Company

To find out more – get in touch


Birwelco USA Inc.
20405 SH 249 Suite: 600, Houston, TX 77070 USA
Tel: (832) 916-4130

Our Clients

waste heat recovery units
direct fired heaters
Once Through Steam Generators
Heat recovery steam generators


Birwelco USA Inc. (BUSA) is a leading supplier of specialized services and support for fired heaters and furnaces from design conception to turnkey implementation. Solutions include studies, on-line services, revamps and complete rebuilds, all with a focus on minimising downtime and maximising return on investment. Understanding the owner’s unique needs and delivering the turnkey solutions to meet those needs is at the core of every BUSA project.

Tube Supports

The number one leading cause of unplanned shutdowns or reduced throughput rates for a fired heater is the imminent or actual rupture of a coil tube.

Today’s heater operation is using newer technology burners with drastically different flame profiles to process the most economical shale crudes. Both factors are contributing to a sharp rise in the frequency and magnitude of coil movements (vertically and laterally) seen during operation, often compromising the existing tube support system.

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