Boiler Tube Repair: How It Works | Rasmussen Mechanical
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 the way it was designed.
What Causes Boiler Tube Failure
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. 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 CO2
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 all cracks and damaged tubes have been located, they are then removed from the boiler. This will occasionally require tube sheet replacement or repair as well.
4. New boiler tubes are then installed in their place. Tubes can be rolled, beaded or welded 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. All repairs must be submitted to the nation board and any other local regulatory agencies.
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
For 50 years we have been the Midwest choice for boiler tube repair. Call us at 1–800–237–314, chat with a support agent, email sales@rasmech.com, or simply contact us online. Whatever your boiler room needs, we’re here to help!
Originally published at https://www.rasmech.com on May 7, 2021.
