How to Do Process Heater Inspection – Aramco Mechanical QC Notes

What is Process Heater or Industrial Heaters?

A process heater, also known as an industrial heater, is a device used in various industrial processes to heat fluids, gases, or other materials to a desired temperature. These heaters are used in a wide range of industries, including oil and gas, petrochemicals, chemicals, power generation, food processing, and more.

The heaters may use different fuel sources, such as natural gas, fuel oil, coal, or biomass, and may employ various heating methods, such as combustion, electric heating, or steam. Process heaters are crucial components in many industrial processes, as they help to maintain consistent operating temperatures and enable the efficient processing of materials.

Process Heaters Inspection Guidelines

Here is a summary of the steps a set of instructions related to the inspection of a process heater.

1. Check the heater drawing, construction code, and materials used for various components of the heater such as radiant and convection tubes, tube support, tube guide, refractory, Skin Thermocouple and or Thermo well, Damper, and Baffle plates. Note the dimensions of each item, including its diameter, length/height, and thickness as applicable to the heater type (cylindrical or horizontal). Also, inspect the burner assembly and orientation of the burner tip and its material.
2. Read the heater file and note the history of corrosion, tube failures, over heating, and other replacement or repairs.
3. Carry out a joint inspection of the heater, verifying that necessary equipment such as blinds, ventilation, lighting, and scaffolding have been provided. Obtain an entry permit to ensure that the heater is safe to enter and inspect. During inspection, keep a man watch for safety purposes.
4. Carry out an external inspection of the heater to check for external flue gas leaks, external damage to the heater casing and structure, burner blocks, and fuel leaks. It is recommended to conduct an infrared survey before shutting down the heater to identify hotspots, hot tubes, and any refractory damage to the heater casing.
5. Gas test the heater internally before entering for internal inspection. Ensure that the heater has adequate venting and is free from any foul smell or toxic gas release while scales or deposits are disturbed. Check for adequate lighting and scaffold as required for inspection. Ensure that a man standby is available for safety and company loss prevention.
6. Start a preliminary visual inspection of the heater internally, paying attention to the heater floor, burner assembly, burners, and snuffing steam connections, the refractory walls, bottom, mid and top tube guides, and the seat as applicable and accessible.
7. Inspect tubes, elbows/U-bends, and skin thermocouples for significant overheating, bulging, bowing/distortion, and scaling of tubes. Recommend cleaning for detailed inspection.
8. Evaluate if the heater tubes are adequately cleaned for inspection. Request further cleaning if necessary.

Check tube surfaces externally for any significant corrosion, mechanical damage, bulge, tube distortion, or bowing. Request ultrasonic testing (UT) on the full length of tubes, including elbows at top and bottom, random hardness at the most overheated area/flame-impinged area. Radiograph (RT) the inlet and outlet tubes, including U-bends, for metal loss, coking, cracking, etc. Concentrate on the shock and hip tubes if any. Compare and evaluate results well in advance to predict problem areas.

You can ensure that the process heater tubes are thoroughly inspected and evaluated for any significant issues, such as corrosion, mechanical damage, and erosion/corrosion. It is crucial to request further cleaning if necessary to ensure that inspection is carried out effectively. Additionally, by requesting UT and RT testing, you can accurately assess the condition of the tubes, and any problem areas can be identified and addressed promptly.

1. Get thermo-wells removed and skin thermocouples cleaned for visual and differential pressure (DP) testing, and evaluate results. Request thermowell continuity test for acceptance.
2. Check snuffing steam nozzles/connection for plugging and corrosion.
3. Check the floor bricks or refractory and wall refractory for any significant damage and request repairs as applicable.
4. Inspect the bottom U-bend and attachment tube guide for corrosion damage externally.
5. Inspect closely the interim tube guides, top tube guides, and tube supports for damaged bolts, erosion/corrosion, and damage to tube contact.

In summary, the process for inspecting a process heater involves checking the heater drawing, construction code, materials, and burner assembly. Then, carrying out an external inspection and gas testing before entering for internal inspection.

During the internal inspection, attention is paid to the floor, burner assembly, refractory walls, and tubes for signs of damage, distortion, or bowing. If cleaning is not adequate, further cleaning is requested, followed by UT checks, RT checks, and DP tests.

After completion of the inspection, repairs and cleaning are carried out as needed, and a final inspection is done to assess the heater’s condition for operation during the next EIS period. If the heater is not compliant with the inspection findings, a FFS assessment is done, and a partial or full re-tubing is requested for the next EIS period.

It is important to ensure that all applicable standards and codes are followed during the testing and repair process to ensure the safety and integrity of the heater. The SAEP-20, SAES-W-010, SAES-A-004, ASME SEC VIII D1, API STD 530, and API STD 510 provide guidelines for the inspection, testing, and repair of process heaters. It is also important to follow the test procedure provided by the operation engineer of the unit or to submit a waiver in advance, as required by SAEP-20. Finally, all test and waiver documents should be filed for reference.