API 560 Fired Heaters: Design and Industrial Applications
Fired heaters are essential equipment in many oil and gas, refining and petrochemical facilities. They provide the thermal energy required to heat process fluids and feedstocks to specific operating temperatures before they enter downstream equipment or processing units.
In refinery applications, the design, fabrication and inspection of these heaters must follow recognised engineering requirements to support reliable and safe operation.
API 560 fired heaters are associated with the American Petroleum Institute’s standard for fired heaters used in general refinery service. The standard provides requirements and guidance covering key aspects of heater design, materials, fabrication, inspection and testing.
Understanding the purpose of API 560, the main heater configurations and their industrial applications is important when specifying process heating equipment for demanding facilities.
What Is API 560?
API Standard 560 is titled Fired Heaters for General Refinery Services.
It establishes requirements and guidance for the design and specification of direct-fired heaters used in general refinery service. Its scope includes areas such as materials, refractory lining systems, fabrication, inspection, testing and preparation for shipment.
The standard also addresses important heater components and engineering considerations, including burners, tubes, supports, combustion systems and associated equipment.
apiwebstore.org+1
API 560 is an engineering standard rather than a specific heater model or configuration. The actual design depends on the process requirements, project specifications, operating conditions and applicable codes.
Important: API 560 should not be confused with API 12K, which is associated with indirect-type oilfield water bath heaters. The two standards address different equipment categories and applications.
How Do Direct Fired Heaters Work?
A direct-fired heater transfers heat to a process fluid through a heating coil exposed to the heat generated by combustion.
The burner produces a controlled flame inside the heater firebox, also known as the radiant section. Process fluid flows through tubes positioned within the heater, absorbing energy from the combustion process.
A typical direct-fired heater includes:
- Burner and fuel system.
- Radiant section or firebox.
- Process heating coils.
- Refractory lining.
- Convection section, where included.
- Exhaust stack.
- Instrumentation and control systems.
- Associated safety and protection systems.
Heat transfer occurs through radiation in the radiant section and, where a convection section is provided, through heat exchange with the hot flue gases.
The exact arrangement depends on the heater type, heat duty, process conditions and design requirements.
Main Types of API 560 Fired Heaters
Fired heaters can be designed in different configurations to meet the available space, process duty and project requirements.
Integraheat designs three principal heater configurations: vertical cylindrical, cabin and box heaters.
Integraheat
1. Vertical Cylindrical Heaters
Vertical cylindrical heaters are widely used in refinery and general process heating applications.
Their design typically features a vertical cylindrical structure with burners located near the base and process coils arranged around the radiant section.
Common characteristics include:
- Compact footprint.
- Relatively straightforward structural arrangement.
- Suitability for a range of refinery heating duties.
- Potential for vertical or helical coil arrangements, depending on the design.
The final configuration depends on heat duty, tube layout, allowable heat flux, process conditions and project specifications.
2. Cabin-Type Heaters
Cabin heaters use a rectangular or box-like enclosure with process coils arranged within the radiant and convection sections as required.
This configuration can offer flexibility in coil arrangement and heater layout, particularly where larger duties or specific site constraints influence the design.
The structural design, burner positioning, refractory arrangement and access provisions must be developed around the project requirements.
3. Box-Type Heaters
Box-type heaters feature a rectangular firebox and can be configured for different process duties.
They are commonly considered where the required heating capacity, process coil arrangement or site layout makes this configuration suitable.
As with other fired heater types, the design must account for combustion performance, heat distribution, tube temperatures, mechanical loading and maintenance access.
Key Industrial Applications of API 560 Fired Heaters
API 560 fired heaters are primarily associated with general refinery service, but direct-fired process heaters are also used in other industrial facilities where the process requirements and applicable specifications allow.
1. Crude Oil Heating
Crude oil heating is one of the common applications of direct-fired process heaters.
Crude oil may need to be heated before entering certain refinery operations to achieve the required process temperature and support downstream treatment.
The heater duty is determined by factors such as crude oil composition, flow rate, inlet temperature, target temperature and operating pressure.
2. Refinery Process Heating
Refineries use fired heaters to provide heat to different process streams across their operating units.
Depending on the refinery configuration, these duties may include feed heating and other process heating requirements.
The heater design must match the process conditions and the specific requirements of the unit it serves.
3. Petrochemical Processing
Petrochemical plants require controlled heating for selected feedstocks and process streams.
Direct-fired heaters can provide the required thermal energy where the process requires a fired heating arrangement.
Design considerations include temperature uniformity, process fluid characteristics, tube metallurgy, heat flux and combustion performance.
4. Hot Oil Heating
Direct-fired heaters can also be used to heat thermal oil in industrial circulation systems.
In this arrangement, the oil circulates through heater coils and transfers heat to process users elsewhere in the plant.
The design of a hot oil heater must account for the thermal fluid’s properties, circulation rate, operating temperature and protection against overheating.
Key Design Considerations for API 560 Fired Heaters
A fired heater must be engineered as a complete system. Selecting a configuration based only on its nominal heating capacity is not sufficient.
Process Design
The process design establishes the required heating duty and operating conditions.
Important inputs include:
- Process fluid composition and physical properties.
- Flow rate and operating pressure.
- Inlet and required outlet temperatures.
- Allowable pressure drop.
- Operating and design cases.
- Required turndown and operating flexibility.
Thermal Design
Thermal design determines how heat is transferred from combustion gases to the process fluid.
It includes consideration of radiant and convection heat transfer, heat flux, tube temperatures and overall heater performance.
The design must avoid unacceptable local overheating and remain suitable for the specified operating conditions.
Mechanical Design and Materials
The mechanical design addresses the structural integrity of the heater and its components.
This includes tube materials, supports, refractory lining, casing, connections, thermal expansion and other mechanical loads.
Material selection must account for the process conditions, metal temperatures, corrosion risks and applicable design requirements.
Combustion System
The burner and fuel system must provide the required heat input while maintaining stable combustion.
Design considerations include:
- Fuel composition and availability.
- Burner capacity and turndown.
- Combustion air supply.
- Draft arrangement.
- Flame characteristics.
- Emissions requirements.
- Burner management and safety controls.
Inspection, Testing and Maintenance
Inspection and testing requirements are important throughout fabrication and equipment delivery.
The project specification and applicable standards determine the required inspection activities, testing procedures and documentation.
Maintenance planning should also consider access to tubes, burners, refractory, dampers and other components that may require inspection or replacement during operation.
Why Is API 560 Important for Refinery Projects?
API 560 provides a recognised engineering framework for fired heaters used in general refinery service.
It helps establish common requirements for design, specification, materials, fabrication, inspection and testing, supporting communication between the owner, engineering contractor and equipment supplier.
For projects in the Middle East, including Saudi Arabia and the UAE, the applicable project specifications and local requirements should be reviewed alongside the relevant API standard.
The standard edition and any applicable addenda should always be confirmed at the start of the project. API’s published catalogue lists the sixth edition of API STD 560 as published in January 2026.
apiwebstore.org+1
Choosing an API 560 Fired Heater Supplier
Selecting a fired heater supplier involves more than comparing equipment dimensions or rated heat output.
The supplier should understand the process requirements, relevant engineering standards, combustion system, fabrication requirements and the operational needs of the facility.
Key considerations include:
- Experience with refinery and process heating projects.
- Capability to engineer different heater configurations.
- Understanding of API 560 and related standards.
- Integration of burners and combustion controls.
- Fabrication, inspection and testing capabilities.
- Installation, commissioning and aftermarket support.
Integraheat has extensive experience in the design and engineering of direct-fired heaters to API 560 and ISO 13705, offering cylindrical, cabin and box configurations for demanding industrial applications.
Integraheat
Explore our Direct Fired API 560 Heaters to learn more about our design approach and available configurations, or contact our team to discuss your project requirements.