Boiler Corrosion & Scale Preventive Treatment

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Boiler Corrosion & Scale Preventive
Water Treatment

Boiler Corrosion & Scale Preventive Treatment

Boilers are expensive pieces of machinery essential for heating up living spaces, manufacturing processing, or air and surface sterilization. Cast iron and steel are the most common materials used in these boilers. These metal surface materials react with water and create two main issues: scale and corrosion. Chemical water treatment chemicals can effectively resolve and prevent these issues.

Boiler Preventive Chemical Water Treatment

An important factor when working with boiler chemicals is to balance the pH effectively. Alkalinity builder chemicals (raising the pH) help with corrosion and acid chemicals (lower pH) help with scale/foaming. You will not want to go too much in either direction. Your boiler manufacturer should have guidelines on the proper pH level to keep your system at.

The Problem of Scale in Boilers

Scale
Layers of suspended solids build up over time. The insulation at heat transfer services cause serious inefficiency.

On the waterside of the boiler, the first thing you should worry about is scale. Scale deposits form an insulation layer that reduces the heat transfer in your boiler. This reduces efficiency, in turn, increasing your energy costs. Less than 1/8 inch or 3.2 mm can result in a 15% drop in efficiency. The more scale that builds up, the higher the inefficiency will be. When it comes to removing scale deposits, it generally takes as long to remove as it did to build up. Therefore, if you can prevent it or remove it as soon as possible, it will save you a lot of headaches. Hard water has more minerals that can form scale deposits.

Efficiency Loss5%10%15%20%
Scale Buildup in mm.41.12.44.5
Scale Buildup in inches.016.043.094.177

(Data from the company, “Accepta”)

Scale Inhibitor Boiler Chemical

Solid substances that form scale consist of calcium carbonate, silica, magnesium, phosphate, and iron. These dissolved substances will leave scale deposits over time if the water is left untreated. Thankfully, scale inhibitors can prevent this.

  • Polymers- These dispersants break down deposits of suspended solids.
  • Polymers & Phosphates- This works by neutralizing hardness in the water. They form solid substances that do not adhere to the surfaces of the boiler and can more easily be flushed out.

Corrosion Issues in Boilers

Corrosion
Pitting, surface, crevice, and other forms of corrosion will occur on untreated metal surfaces. In addition to worse heat transfer, it can lead to mechanical damage.

The iron in boilers reacts with oxygen/water which disintegrates the metal and creates rust. The harder the water and the higher the temperature it is running at, the more corrosive the water will be. High oxygen levels will also lead to an increased amount of corrosion. The chart below shows how oxygen levels decrease with higher temperatures. Although oxygen levels are lower, they are still becoming more corrosive at higher temperatures as the corrosive agents (water and oxygen) have increased kinetic energy. This energy creates faster reactions, in turn, leading to more corrosion.

Dissolved Oxygen in mg/l141197.56.55.55431.50
Temperature °C 0102030405060708090100
Temperature °F 32506886104122140158176194212

(Data from the company, “B & V Chemicals”)

Oxygen Scavenger Boiler Chemical

Oxygen scavengers get rid of dissolved oxygen in the water. The amount of oxygen scavengers needed will depend on the concentration of oxygen in the water.

  • Sulfite- At high temperatures, less of this is required. However, sulfites increase the number of solid materials suspended in the system, requiring it to be flushed more often.
  • Tannin, Carbohydrazide, & DEHA- These are typically more expensive than sulfite. With this more expensive chemical, you get chemicals that are not dependent on temperatures. Additionally, they do not affect the number of solid materials suspended in the system. This leads to fewer flushes being required.

Chardon Labs Boiler Preventive Maintenance Water Treatment

Expert Boiler Water Treatment Services
sales@chardonlabs.com
(380) 224-7395

Our full-service boiler treatment services involve providing and installing necessary water treatment equipment such as feed and controllers. We provide scheduled treatment at regular intervals. We do not miss scheduled treatment, surveys, or meetings. If we say we will be there we will show up. Our chemicals are specifically tailored for your boiler system to keep it operating as efficiently and problem-free as possible. Need boiler treatment help? Fill out a fast contact form or get in touch by calling us at (380) 224-7395. We look forward to helping you!

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Matt Welsh

Matt Welsh is the Vice President and Water Consultant at Chardon Labs. He helps consult a wide range of customers utilizing various methods of water treatment, from chemical to chemical-free approaches, large and small applications, and across a wide range of geographical influences. With 20 years of water treatment experience, including a wide range of troubleshooting and service in potable water and non-potable HVAC and industrial applications, he is an expert in water treatment chemistry for cooling towers, boilers, and closed-loop systems.

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