13 Steps to Safely Clean and Maintain Heat Exchangers

Heat exchanger safety precautions are a serious matter. Cleaning a heat exchanger keeps it clean and free of fouling, this increases heat efficiency, lowers operational costs, maintains a high level of Indoor Air Quality, and keeps temperatures consistent throughout a facility.

Safety should be the highest priority when cleaning heat exchangers. The chemicals, solvents, and cleaning agents used to remove fouling and scaling must be handled with care. Careful management of high temperatures and pressures must occur during the cleaning process. Protective gear is needed, as well as an awareness of the fire hazards, and electrical and mechanical dangers that may exist in the furnace room.

Understanding heat exchanger cleaning safety rules and precautions will help building operations managers successfully and safely clean heating equipment.

Types of Heat Exchangers

It is vital to know the heat exchanger type prior to attempting to clean it. Many types of furnace equipment can be used.

Common heat exchanger types include:

• Shell and Tube: Comprises a shell with tubes inside. Most often used in oil refining, chemical processing, and power generation.
• Plate: Stacked metal plates that create alternating hot and cold fluid channels. These heat exchangers are widely used in HVAC, refrigeration, and food processing.
• Finned Tube: Tubes with finned surfaces for increased heat transfer area. These heat exchangers are commonly used in air conditioning, refrigeration, and heat recovery systems.
• Double Pipe: Two concentric pipes with one fluid in the inner pipe and the other in the annular space. Most often used for low-pressure applications.
• Spiral: Two coiled flat plates forming spiral channels, efficient for highly viscous or fouling-prone fluids.
• Regenerative: Rotating matrix with heat-absorbing and heat-rejecting sections for heat recovery, commonly used in HVAC and industrial processes.

Which heat exchanger type is used depends on the application, heat transfer requirements, fluid characteristics, space constraints, and operating conditions. Knowing which type a system uses dictates heat exchanger cleaning methods and heat exchanger cleaning chemicals.

Heat exchanger safety also can be addressed in the design phase, ensuring the furnace room and structural design of the heating equipment allows technicians to safely clean heat exchangers.

The manufacturing plant can also upgrade safety with functioning alarm systems, such as carbon monoxide detectors and smoke alarms, and written standard operating procedures that detail appropriate cleaning steps and precautions. Every maintenance job is unique and should be approached with heat exchanger safety precautions in mind.

12 Steps to Keep You Safe and Get Heat Exchangers Clean

Following these steps will help technicians incorporate the best safety measures when cleaning heat exchangers.

1. Review Manufacturer’s Guidelines. Examine the heat exchanger user manual and other manufacturer documentation to gather specific instructions and recommendations for heat exchanger maintenance procedures, suitable chemical cleaning agents, and safety precautions. Developing a heat exchanger maintenance checklist based on these steps ensures a consistent chemical cleaning process is always followed and avoids problems such as cracked heat exchangers.
2. Wear Protection. Follow plant policy for personal protective equipment (PPE). Don required PPE, such as safety goggles, gloves, and a respirator mask. Doing so will protect technicians from harmful substances or chemicals during furnace repair and cleaning.
3. Shut off and Isolate. Make sure all inlet valves are securely fastened and tagged. Close the supply and return water valves. Position a ball valve on the low point of the heat exchanger, which will serve as an entry point for the cleaning agent and will prevent backflow. Shutting off all valves and isolation points to stop the flow of fluids through the system ensures a safe and inactive heat exchanger during the tube cleaning process.
4. Perform an Inspection. A heat exchanger risk assessment checks for visible signs of damage, such as corrosion, cracks or other abnormalities. Check for fouling or corrosion and identify the type of fouling to determine the optimal cleaning method. This may include chemical or mechanical cleaning or a combination of both. Test inlet and outlet temperatures. Inspect tubes for damage and replace if needed.
5. Release Pressure and Drain Fluids. Make sure the heat exchanger’s pressure goes down using a safety relief device, checking that the pressure relief valve reads zero. Wait until the system cools before doing anything else to minimize exposure to hot fluids. High pressure cleaning can reduce safety.
6. Get Attached. Attach a circulation hose to pump fluid into the bottom and return fluid out of the top. The exit point must be at the exchanger’s highest point. This ensures the cleaning agent comes in contact with all interior wetted surfaces and that upper interior areas do not become air bound with CO2 or foaming.
7. Fill Up and Test. Fill the heat exchanger with water and perform a hydrostatic test by turning on the pump and circulating the water. This action assures the exchanger is isolated and none of the cleaning agent will be needlessly lost. Bleed off water equal to the volume of chemicals required for cleaning. If too much water is bled off, add some back in to complete the circulation loop. Additional water may be needed during the cleaning process as deposits are dissolved to make sure dissolved deposits do not stick somewhere within the system.
8. Check It Out. Periodically check isolation valves as they may have initially seated against the scale. As chemicals dissolve the scale, this action will help prevent product loss.
9. Give It Time. Allow sufficient cleaning time. Circulate the cleaning agent for the recommended timeframe.
10. Rinse Thoroughly. Empty the heat exchanger of any dangerous chemicals after the solution has completed its job. To flush the heat exchanger, turn off the circulation pump, remove the return hose from the recirculation system, and put it in a drain. Add a freshwater hose to the recirculation bucket on the pump system and turn the pump back on. Continue running clean water through the heat exchanger until the return water is running clear. This action will also flush out the pump system. As an added safeguard, technicians can reverse the hoses, so they pump into the top and out the bottom. This will flush away debris that has settled on the bottom.
11. Inspect and Reassemble. To avoid leaking, carefully install a new gasket focusing on the head. Poor installation can cause leakage. Disconnect the hoses. Close the valves used in circulation and open the valves for the supply water. The heat exchanger can now be returned to service.
12. Test and Restart. Perform required system checks and tests as recommended by the manufacturer to ensure the heat exchanger is functioning properly. Once verified, restart the system while monitoring it closely for irregularities.
13. Follow the Law. As the above steps are carried out, be sure to follow all local regulations for discharge. These can vary from city to city and state to state.

Next Steps

Let’s work together to ensure you are cleaning heat exchangers safely to prevent senseless injuries and deaths. Following heat exchanger safety precautions is a good step and can be accompanied with Goodway’s Industrial Descaling Systems and Solutions to prevent buildup in plate heat exchangers. Need help selecting a descaler? We’ve outlined which descaler will best meet your needs here. Regular cleaning will keep heat exchangers operating at peak efficiency.