How to Clean Scale From Your Boiler

What Causes Boiler Scale?

Scale is caused by dissolved minerals present in the water crystallizing and becoming solid deposits; these deposits bind to the metal surfaces in the boiler. There is a phenomenon called supersaturation, in which there will be too many dissolved solids present in the water for it to be able to hold any more. At this point, the solids become insoluble and form solids. The level of supersaturation is influenced by several factors, including temperature and pH levels. Areas with hard water have a high number of dissolved solids, and changing the boiler water chemistry is recommended to prevent excessive scale deposits.

Why You Need to Clean Boiler Scale

When scale precipitates and forms within the boiler system, it can cause an isolating effect, leading to boiler scale issues and increased 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.

Schedule Water Treatment

Boiler Cleaning Preparation

The procedures utilized to clean boiler scale will likely need to be done repeatedly to effectively remove the scale. The hydrochloric acid used for this cleaning creates fumes that need proper ventilation. Make sure to have that beforehand. If calcium carbonate does not make up most of the scale present in the boiler system, you will need to use additional chemicals.

Procedure to Clean Scale From Your Steam Boiler

After turning off the boiler, follow this procedure to clean the scale from your steam boiler:

1. Make sure to keep the manhole cover open; this will allow for regular inspections while you are cleaning the system. Isolate the boiler by closing the gate valves as close to the vessel as possible.
2. 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.
3. Add water to the boiler, filling it up as much as you normally would.
4. 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 and 3.
5. 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 temperatures above the temperature cause 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.
6. 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.
7. 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.
8. 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.
9. If cleaning is successful, immediately refill the boiler with water and add chemicals to get the pH to 11 and sulfite to 200 ppm. Replace the manhole. Set the temperature to the boiler’s usual running temperature.

Post-Cleaning Maintenance Tips to Prevent Scale Buildup in Your Boiler

To help prevent future scale and maintain a clean system, follow these maintenance tips. This will prevent most future cleanings.

• 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 to prevent boiler scale.
• Measure the total dissolved solids (TDS) in your water, which are dissolved salts that can cause scaling in boilers. Hard water will have high amounts of total dissolved solids present. Soft water will have a much smaller concentration of these.
• 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.

Boiler Scale Inhibitors

Scale inhibitor chemical helps prevent new scale from forming in a boiler system. It is one of the most important regular maintenance steps for operating a boiler. Scale inhibitor chemicals work by binding to various minerals dissolved in the water. The inhibitors then interrupt the mineral formation that forms scale. There are a few common types of scale inhibitors. These include polymers, phosphonates, phosphates, and polyphosphates.

Chardon Labs- Our Effective Boiler Maintenance

Chardon Labs uses water chemistry to effectively prevent and treat scale in your boiler system. We take regular tests, measuring aspects of your boiler water system such as its hardness, alkalinity (pH), conductivity, etc.

Based on our analysis of a wide range of boiler customers across many industries, we can identify patterns that can lead to maintenance issues, such as scale. By doing this, we can specifically tweak your water chemistry by adding chemicals, flushing, filtering, etc., to prevent issues. Additionally, we try to make your boiler operate cost-effectively by decreasing the amount of power and water consumed.

Scale can be particularly harmful as it significantly reduces heat transfer, leading to less effectiveness and higher bills from boiler operation. This is why Chardon Labs offers a scale-free guarantee provided that your boiler is set up with our minimum equipment requirements.

Boiler Scale Prevention Services

Set up a boiler water treatment plan today! Let us come out and survey your equipment to effectively prevent scale and other common boiler issues. Our surveys are free and can be booked the same week. Why not get a qualified opinion of your boiler’s condition, your maintenance program, and your maintenance equipment? Reach out here to book a survey or learn more!