Boiler safety lessons
An average of 17 boiler incidents occurs each year.
These cracked boiler sections are the result of cold water sprayed on the boiler to put out a fire. Photo credit: Ray Wohlfarth
This is an old boiler with one low-water cutoff valve. Old boilers should be brought up to code with two low-water cutoffs. Photo credit: Ray Wohlfarth
An example of improper relief-valve piping. Photo credit: Ray Wohlfarth
The solitude of a peaceful West Virginia town was interrupted on a frigid Monday night in February when the smoke and fire alarms shrieked at 11:30 p.m. inside the fire department. The source of the alarms was the local elementary school boiler room. Since the call emanated from a school, the alarm went out to several of the adjacent fire companies.
In all, six fire companies responded to the call. It amazes me that these brave individuals choose to run into a building when everyone else is running out. The fire department broke through the outside door and carried their heavy equipment down the long hallway to the boiler room door. Once open, the firemen were greeted with heat and what was thought to be white smoke.
Upon reflection, it was more likely steam vapor from a discharging boiler relief valve or a leak in the 30-year-old cast-iron boiler. Steam filled the room, making it almost impossible to see. Since steam displaces oxygen, breathing without masks would have been rather challenging in the equipment room. The hot, moist air would make it very dangerous around the electrical panels and controls as well.
Their training and instruments led the firemen to the boiler as the root of the incident. They used their tools to pry the metal jacket away from the boiler. Inside the jacket, they found the glowing red sections of the old cast-iron steam boiler. They trained their fire hoses on the radiating cherry sections and opened the brass valves, spraying cold water onto the overheated sections.
The cold water caused the sections to crack, spilling more steam to the room. Thankfully, someone was able to shut off the gas power burner. The threat was extinguished but the boiler was ruined. The school had rooftop units that allowed heat to be maintained in the building. No injuries were sustained but this could have been so much worse.
This boiler had been inspected in August by a certified boiler inspector. I am not sure whether it was divine intervention or just plain luck that allowed these brave firefighters to walk away from this. When water is turned to steam, it will expand at 1,700 times its volume. When that steam is quickly cooled, it causes a reaction called “condensate-induced water hammer.”
It has an incredible amount of power, often generating more than 1,500 lb. of pressure per sq. in. This pressure can obliterate just about anything in its way as it is almost 10 times the rated pressure of standard pipe fittings and 20 times the pressure rating of the school’s boiler.
A local church in my area had an old cast-iron boiler explode when cold makeup water was dumped into the searing boiler. The boiler inspector told me the relief valve was never found and the local newspaper reported the cast-iron boiler parts were like shrapnel, shredding anything in their path.
Averting a deadly disaster
When I visited the school site, my first thought was how lucky everyone was. This could have been a catastrophe that could have injured or killed many people had it occurred during the day, including the children attending the school. In addition to human damage, the building could have sustained severe structural damage. My second thought was how a situation such as this could be avoided in the future.
The old cast-iron boiler was installed more than three decades ago and had only a single low-water cutoff . In addition to being a low-water cutoff, this control could feed cold water into the boiler via an internal float valve. Another problem is that the relief valve was not piped to the outside as the newer codes for steam boilers require.
The low-water cutoff is the leading mechanical cause of boiler accidents. New boiler code mandates that new low-pressure steam boilers have two low-water cutoffs: a primary and an auxiliary. The auxiliary low-water cutoff should be installed at a lower elevation and have a manual reset button. It is more or less a failsafe control.
Because this boiler was installed prior to the new codes, it was grandfathered in and did not have to meet the new regulations. I wonder if it is now time to rethink the “grandfather” clause that old pieces of equipment use. I believe it should be required that every piece of heating equipment have updated safety controls to meet the current safety codes, if possible.
The American Society of Mechanical Engineers’ Controls and Safety Devices 1 code requires a door switch at every exit of a boiler room. This switch cuts the power to the boilers. It is not code in every state but I believe these switches should be installed in every boiler room. It is an inexpensive safety device that could save lives and should be recommended to every boiler owner. A simple switch would have shut off the power to the boiler and allowed the first responders to enter a much safer boiler room.
I had to remind myself that first responders are not boiler technicians. All they saw was a glowing charcoal-like ember and their training kicked in. We, as an industry, should offer training for these brave men and women before a catastrophe occurs. They should be instructed on how to safely shut down a boiler in the event of a malfunction.
While boiler explosions seem to gain the newspaper headlines, an average of 17 boiler incidents occurs per year. Compare that with an estimated 500 deaths per year attributed to accidental carbon monoxide poisoning, according to the Centers for Disease Control and Prevention. In any event, I have tremendous respect for these pieces of machinery and they deserve to be maintained properly.
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