Scale buildup in your steam boiler? Learn why scale accumulates, why you should clean it off and how to clean it.
Why Is There Scale on Your Boiler?
Calcium carbonate scale is commonly formed in a boiler system by exceeding the threshold solubility of the water’s mineral content. Most dissolved solids in water become soluble as the temperature of the water increases and thus precipitates on heat transfer surfaces as scale. Oftentimes, the temperature of each boiler tube will vary slightly, and more scale tends to develop on these hotter spots. Without proper chemical water treatment in boilers, scale precipitates and can damage your boiler system.
Why Should You Clean the Scale in Boilers?
When scale precipitates and forms within the boiler system, it can cause an isolating effect, which increases temperature variations. These increased variations can result in leaks in a boiler tube or, in extreme cases, boiler tube rupture. The scale in boilers will also decrease heat transfer efficiency and typically result in higher fuel and energy bills.
If you notice these or other concerns, such as a banging or kettling noise, take steps to address scaling in your boiler system.
How Do You Clean the Scale off of the Boiler? Tips Before Starting
Before you begin cleaning boiler scale, know that you’ll require additional products and steps if you suspect that the majority of the scale is not calcium carbonate. Also, note that it is rare for the entire boiler surface to be completely clean after acid cleaning. You may need to repeat this procedure several times if the severity of the scale is substantial. Lastly, the acid used for this cleaning is hydrochloric acid, which produces fumes with normal use. Be sure to have adequate ventilation to the outside when using this product.
Procedure to Clean Scale From Your Steam Boiler
After turning off the boiler, follow this procedure to clean scale from your steam boiler:
- Isolate the boiler by closing the gate valves as close to the vessel as possible. Keep the top manhole open to allow for periodic inspections during the cleaning.
- Estimate the total number of gallons of water the vessel section will contain. Calculate the amount of initial acid to use to get a 1%-5% concentration of Chardon’s Scalzo in the boiler. Use only Scalzo to prevent excessive steel corrosion while cleaning.
- Fill the boiler to capacity with water. Immediately add the Scalzo followed by a small amount of Chardon’s CTA-800 (4 oz per 1,000 gallons). Check pH before starting the boiler knowing it has not mixed in well just yet. pH should be between 1-3.
- Promptly have the boiler operator operate the boiler to heat the cleaning solution in the boiler to a maximum of 130 degrees Fahrenheit. DO NOT BOIL THE WATER. Be sure to check the temperature since above the temperature causes excessive corrosion of the steel by the chlorides in the cleaning solution. Generally, when the water just starts to move inside the boiler, it is at the correct temperature. The velocity of the water inside the boiler aids in dispersing the dissolved calcium and provides contact of scale with fresh acid to continue cleaning. If an air lance is available, use it to provide an air-bubbling action at the bottom of the boiler vessel, which encourages circulation.
- Continue turning on and off the boiler to maintain the temperature in the range of 100 degrees Fahrenheit to 130 degrees Fahrenheit. Check pH every 15 minutes — it should be 1 or 2. If the pH is higher, add Scalzo to depress it back to 1-2.
- Continue step 5 until pH remains at 1 or 2 for 120 minutes or more, depending on scale buildup. The system is then as clean as it will be with the current cleaning solution. Neutralize the cleaning solution to a pH of 5 with Chardon’s BD-6 by adding it to the vessel and circulating the mixture for a few minutes. Check pH — add more BD-6 if needed and circulate if necessary. Drain the solution from the boiler as quickly as possible.
- Add water to the vessel and continue rinsing the boiler internals. Drain again and inspect for the level of cleaning success. If further cleaning is desired, repeat the cleaning process with fresh Scalzo.
- If cleaning is successful, immediately refill the boiler with water and add chemicals to get pH to 11 and sulfite to 200 ppm. Replace the manhole and have the operator re-fire the boiler and bring it to normal operating temperature.
Post-Cleaning Maintenance Tips to Prevent Scale Buildup in Your Boiler
Once you’ve addressed boiler scale, maintain a clean system by following these proactive measures:
- Use scale inhibitors with phosphonate, available in different formulations depending on your needs, such as products suitable for systems that come in direct contact with food.
- Conduct routine water testing to monitor water hardness and take proactive measures if necessary.
- Measure the total dissolved solids (TDS) in your water, which are dissolved salts that can cause scaling in boilers.
- Pretreat hard or high TDS water with reverse osmosis, water softeners and demineralizers to remove minerals such as calcium and magnesium.
- Maintain the recommended temperature and pressure in your boiler system.
- Conduct regular blowdowns of your boiler — once a shift or less frequently, depending on your usage — to remove sludge and dissolved solids.
- Utilize remote monitoring and automated control systems to track water quality and boiler performance.
- Conduct regular maintenance and inspections or entrust regularly scheduled testing and treatment to Chardon Laboratories.
Why Choose Chardon Labs for Industrial Boiler Maintenance?
Treat and prevent scale buildup with services from Chardon Laboratories. We will send our uniformed technicians in fully stocked trucks to complete preventive maintenance at an agreed-upon annual price.
Our service technicians are familiar with boiler requirements in industries ranging from health care to breweries, manufacturing and food processing. We will collaborate with you to outline a customized treatment approach so your facility can maximize uptime, lower energy and water use, and eliminate the need for frequent repairs.
Your facility can also benefit from our Scale-Free Guarantee. If your system meets our minimum equipment standards — which we can help you meet — we’ll cover the cost of any scale removal should buildup start occurring again.
Prevent Scale in Your Boiler With Treatments From Chardon Labs
Maintain an efficient, scale-free boiler with Chardon Labs. Contact us to arrange a free survey of your boiler system so we can determine its current status and begin developing a treatment and maintenance plan.
