Getting ready to start up your boilers for this season? Great! But before you flip the switch, you may want to read this post. You could be making a mistake that could take years off the life of your boiler.
First, let me start by saying that we are discussing water treatment for steam boilers here. While there are other potential issues that need to be contemplated when starting up a hot water boiler system, these types of boilers are generally more forgiving than steam boilers, especially high pressure steam systems. So we are going to concentrate on steam boilers in this post. (Also, this post is assuming that you are using softened water to fill your boiler. If you are not filling your steam boiler with soft water, you potentially have much, much bigger issues.)
Second, this post assumes that you are, or have on staff, a licensed, certified and/or experienced boiler operator capable of running your steam boiler. IMPORTANT: Only operators that are trained and certified to run a high pressure steam boiler should be doing so. Please follow the rules and regulations that govern this matter in your country/state/etc. For example, to operate a high pressure steam boiler in New York City, you must have a license to do so.
That said, here is something that you should know about steam boilers that may sound weird at first: Steam boilers are not really the best vessels for heating up water. That sounds crazy doesn’t it? But it is absolutely true; they are not the best vessels for heating up water. Many seasoned boiler operators will say “Hey, everyone knows that you never add cold water to a hot boiler!” And that is 100% true, but that’s not what we are talking about here. We are talking about using cold water to fill your boiler for the initial startup. As an important aside: adding cold water to a boiler that is already producing steam could cause an explosion; so you definitely want to avoid that. Here is a pretty photo from report that was prepared by the Chief Boiler Inspector of the Tennessee Department of Labor and Workforce Development regarding a boiler explosion at an extrusion plant in Paris, Tennessee on June 18, 2007. Thankfully no one died, however there were severe injuries.
Why is that so important?
Here is The Problem
Even though it sounds like it should be, the steam vessel in a boiler is not the best place to bring cold water up to a boil. This is important for three reasons:
- Cold water is rich in dissolved oxygen.
- When oxygen is liberated from cold water is can wreak havoc on metal. (Hence the term: “oxidize.”)
- The best way to liberate oxygen from water is by heating it.
You may be asking yourself the question: “Who cares?”
The answer is: If you operate a steam boiler, you should care… a lot.
Putting oxygen-rich, cold water in a boiler before start up is big no-no. As the water heats to temperature to produce steam, oxygen can be liberated at exponential rates.
What is your boiler made of? You got it: Metal… (You can see where we are going with this.)
At the phase change of the water in the vessel going from liquid to gas, the internal metal components will be exposed to and under attack by liberated oxygen. This causes oxygen pitting on those surfaces inside your boiler. If you operate a fire tube steam boiler without a DA tank, you may have seen these pits on the surface of the tubes. Depending how severe, they can look like someone mechanically drilled small holes in the tubes. While the “pit” or hole might not completely puncture the tube today, one thing is certain: That area of the pipe is compromised and will be the future site of ongoing corrosion. If you do a “wet layup” of your boilers in the off-season, you may be causing further damage. Microbial metal eaters (bacteria) love to hang out in those tiny well-protected pits, and once they decide to make a meal out of your boiler tubes, you are in trouble. They’ll have run of the house until someone turns the lights back on next winter.
So what do you do? You have to fill the boiler with water at some point, right? Well, you'll just have to read our very cleverly named follow-up post to get that answer. It's entitled: Cold Water In Your Boiler Causes The Worst Brain Freeze Ever - PART 2
In the meantime, if you would like to avoid some of the biggest mistakes that we see in the water treatment of boilers, please download our free eBook below! It is aptly named "10 Huge Mistakes Facilities Make in Boiler Operation and How to Avoid Them!" It is one of our most downloaded eBooks and it is completely free. No strings attached.
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Greg Frazier is an expert in Industrial Water Treatment and is currently the ManagingPartner of Clarity Water Technologies. He has over 18 years of Industrial Water Treatment experience and holds a degree in Chemical Engineering from the University of Tennessee.