How to Chemically Clean Steam Boilers

This procedure is for cleaning carbonate-based mineral scale from the waterside of steam boilers.

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Additional products and steps will be required if you suspect that the majority of the scale is not calcium carbonate. Also, note that it is rare that the entire boiler surface is completely clean after acid cleaning. It is difficult to get enough circulation and velocity to all parts of the boiler to remove all the scale. This procedure may need to be repeated 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.

Follow this procedure below to get the best results:

1. 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.
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 Scalzo in the boiler.  Use only Chardon Scalzo to prevent excessive steel corrosion while the cleaning is taking place.
3. Fill the boiler to capacity with water. Immediately add the Chardon Scalzo followed by a small amount of specialize Chardon polymer (4 oz. per gallons).  Check pH before starting boiler knowing it has not mixed in well just yet.  pH should be between 1-3.
4. Promptly have the boiler operator operate the boiler to heat the cleaning solution in the boiler to a maximum of 130 F. 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.
5. Continue turning on and off the boiler to maintain the temperature in the range of 100-130F. Check pH every 15 minutes; (should be 1 or 2).  If higher, add Chardon Scalzo to depress the pH back to 1-2 pH.
6. Continue step 5 until pH remains at 1 or 2 for 120 minutes or more, depending on scale build-up. System is then as clean as will be with the current cleaning solution.  Neutralize the cleaning solution to a pH of 5.0 with Chardon&#;s recommended chemical treatment by adding it to the vessel and circulating the mixture for a few minutes.  Check pH &#; add more chemical treatment if needed and circulate if necessary.  Drain the solution from the boiler as quickly as possible.
7. Add city water to the vessel and continue rinsing the boiler internals. Drain again and inspect for level of cleaning success.  If further cleaning is desired, repeat cleaning process with fresh Scalzo.
8. If cleaning is successful, immediately refill the boiler with water and add chemicals to get pH to 11 and sulfite to 200 ppm. Replace manhole and have operator re-fire the boiler and bring to normal operating temperature.

Boilers and heating exchangers after being used for a period of time need to be descaled to ensure efficient heat exchange. So, how to clean the boiler and other heating exchangers? What chemicals should be used? What to keep in mind when doing this? Let&#;s find out more details through the article below for cleaning boiler and also cleaning other industrial systems!

1. Why need to clean boilers and other equipment?

• Remove dirt, grease, and oxidation layer, welding slag when manufacturing, processing, transporting and installing to avoid any problems during operation.
• Remove the deposit layer to increase the efficiency of heat transfer, avoid overpressure causing unsafety.
• Wash the oxidized layer, the corrosion layer before remediating such as painting or replacing to avoid leakage and unsafety.
• Remove deposits to avoid corrosion caused by aerobic microorganisms in cooling water systems.
• &#;

However, the best water treatment and maintenance are required to limit the repeated descaling of the boiler and other industrial machines which will shorten its life

For boilers, periodically need to be inspected (normally, boiler over 10 years old, no more than 2 times / year, less than 10 years old, no more than 1 time / year) and open boiler to check the actual situation of deposits , corrosion to adjust the treatment plan or descale the boiler.

2. Plan an effective, safe and fast cleaning

Inspecting of exisiting condition of equipment, properties of deposits (silica residue, hardness due to heavy metals, grease, etc.) to choose a suitable descaling chemical and appropriate cleaning process, refer to here. : https://uce.com.vn/cleaning-chemical-service-package/

Plan early to do:

• Prepare well for occupational safety.
• Prepare enough replacement materials, chemical, tool and labor.
• Prepare adequate supply water, safe discharge water, avoid affecting biological or chemical wastewater system
• If it is a boiler, it is necessary to cool down with allowed speed.

Operate immediately after cleaning to see if there are leaks or problems was born during cleaning.

3. Basic procedures to clean boiler and industrial equipment

3.1. Basic steps for de-scaling boiler

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Diagram to clean boiler

Depending on kind of each scale that the chemical and process will be different, here are the basic steps for reference. The general time to clean Silica residue is 2-3 days, other residues will be from 1-2 days.

1- Cool down boiler if hot.

2- Open main holes to see the internal condition and deposits (photography, endoscopy, ultrasound of metal thickness ).

3- Connect an external chemical pump to circulate water through boiler.

Boiler bottom valve &#; Cleaning chemical tank &#; Circulation pump &#; Upper main holes

4- Test runing the pump with water.

Step 2: Clean with boiler descaling chemicals

(The parameters of pH, iron, TDS&#; need to be checked many times in this step)

1- Pumping anti-corrosion chemicals first or can be mixed together with cleaning chemical (15-30 minutes).

2- Circulate cleaning solution, then soak for about 2 &#; 4 hours without Silicat scale, 10-15 hours withi Silicate scale.

3- Continue to add other chemicals to neutralize, circulate for 2-6 hours to ensure discharge pH (or separate this step into a separate cleaning step).

4- Discharge all.

Contact us to discuss your requirements of boiler cleaning brushes. Our experienced sales team can help you identify the options that best suit your needs.