An alarming report written by the Minnesota Department of Labor and Industry details a massive boiler incident that caused a relatively small hot water boiler (625,000 BTU) to explode and literally rip a building apart. In this particular case, the size of the boiler was just under the recommended size to have regular operational inspections completed. For some time, the boiler was in need of extra water and frequent refilling, indicating a hidden leak in the system. This type of leak is usually located in underground pipping and can go unfound for years.
Unfortunately, one day this boiler ran completely out of water, but the burner still heated the internals of the system to very high temperatures. The investigation found that an amount of water made it back into the super-heated boiler and caused the zone boundary to fail. This failure caused a massive explosion that happened in less than a second and with no warning. Luckily, no one was hurt but the pictures are worth a thousand words. The full report can be found here.
Incidents like this bring up a lot of questions surrounding how to properly maintain and operate boilers. There are boiler size guidelines for when this type of operation and inspection is required, and often times, what is required is dictated by the insurance provider of each facility. The major flaw in this system is that smaller boilers, like the one in the explosion, are not required to be inspected. While all hot water boilers are recommended to have an internal inspection and cleaning every five years, a large amount of them may never have an internal inspection done either due to size, budget constraints, or a lack of awareness that one should be done in the first place.
These boilers are not just in big buildings; these boilers are in the places we shop, eat, sleep, work, and take our children. Are these boilers being maintained? When was the last internal inspection and cleaning? When considering the above-mentioned incident, it’s easy to see the importance of properly maintaining and operating these boilers no matter the size. The MN Department of Labor and Industry has information on what is recommended for proper operation on their main boiler page. The site also provides guidelines for both hot water heating boilers and low pressure steam boilers. While these guidelines and recommendations are a great place to start, it’s important to always keep in mind that no boiler it too small to be inspected.