Extreme temperatures and high pressures make boiler tube repair vitally important. When done right, re-tubing can give a boiler new life. Replacing cracked pitted or scaled tubes allows the boiler to function properly.
What Causes Boiler Tube Failure
Embrittlement of a boiler tube causing a crack due to poor water treatment.
Raw water from a well or municipality contains impurities such as suspended solids, dissolved solids, and dissolved gases. Feed water can contain these impurities as well as industrial wastes, sediment, and microorganisms. In the Midwest, we most commonly find calcium, magnesium, and silica. These impurities plus the gasses water can contain can wreak havoc on your boiler tubes. That is why having a good boiler feedwater system is so important.
Oxygen and CO2 even in trace amounts as low as 5 ppm (parts per million) will cause major corrosion damage over time. Dissolved oxygen will react with carbon steel throughout the feed water piping, economizers, and boiler, causing oxygen pitting and eventually leaks. Dissolved CO2 can come from poorly deaerated water or as a byproduct of chemical reactions taking place inside your boiler. When this CO2 travels out of the boiler with the steam, it can make the condensate acidic. This acid condensate will corrode your steam piping while also adding iron to your boiler water.
Dissolved solids such as calcium, magnesium, iron, and silica in feedwater can damage a boiler beyond repair. These dissolved solids come out of solution as the temperature of the water increases, forming a scale on nearby surfaces. In many cases, this scale is first seen in the boiler, where the heat transfer occurs. This scale prevents boiler water from cooling metal heat-absorbing surfaces, leading first to a loss of efficiency. As the problem worsens, the boiler will have a number of issues with uneven thermal growth, such as tube roll leaks. When the scale is so thick that it prevents the boiler water from cooling the heat transfer surfaces, the boiler tubes may completely fail.
How Do We Re-tube A Boiler
1. We start by inspecting the boiler looking for welding defects and scaled or pitted tubes. We can also use dye penetrant testing to more easily find areas where cracking has occurred.
2. The second step is to address why the tubes are failing. When re-tubing is necessary, there is often an issue with the system that needs to be diagnosis. This will prevent the new replacement tubes from suffering the same fate as the failed tubes. This often involves looking at the feedwater systems, deaerators, firing rate and more to determine the cause of the issue.
3. After locating all cracks and tube damage, we remove the effected tubes from the boiler. This will occasionally require tube sheet replacement or repair as well.
4. Next, we install new boiler tubes in their place. We can install tubes by rolling, beading or welding depending on the application. This may include the use of XID tubes.
5. Following installation of the new tubes it is time to test the boiler. This involves hydro testing the system while an inspection agency is present. Any of the alterations go to the nation board and any other local regulatory agencies for their records.
Why Use Rasmech For Your Boiler Tube Repair?
We carry boiler tubes in all sizes and thickness to meet the need of your boiler. We are also an R-stamp certified company. This means we meet standards set forth by the National Board of Boiler and Pressure Valve Inspectors code. Finally, we also have a large boiler rental fleet to keep your business online while we are performing the repairs.
We Can Help
Proper boiler tube repair is crucial for maintaining optimal performance and extending the lifespan of boilers subjected to extreme temperatures and high pressures. By replacing cracked, pitted, or scaled tubes, the boiler can regain its intended functionality. This article explores the causes of boiler tube failure, including issues related to water treatment and impurities, such as dissolved solids and gases. It also highlights the step-by-step process of re-tubing a boiler, emphasizing the importance of diagnosing and addressing underlying system issues. Additionally, the article underscores the advantages of choosing an R-stamp certified company with a large boiler rental fleet. This ensures no downtime during repairs. For reliable boiler tube repair services, contact us at 1-800-237-3141, or via email at sales@rasmech.com.
