What causes boilers to be taken out of service prematurely ?

Most anyone experienced in steam will say " thinning of the plates" or " crownsheet ". It all gets down to metal loss of pressure parts that are costly to repair or replace.

Let's simplify some factors that are inter-related and all contribute to Killing Boilers.

1. Dampness - becauses it is in perfect contact with the steel to " host " the chemical reactions we call rusting and corrosion.

2. Oxygen - yes, we need it to breathe and burn fuels. It also Pits and Rusts Iron. Water has both the Oxygen that is used to make the water plus, extra Dissolved Oxygen that comes from the air. This extra Dissolved oxygen is the Boiler Killer.

3. Acid - water contains a balance of acid and alkali ( base ). When they are in balance, the pH is close to 7, or neutral. When the acids predominate, the pH is less than 7, and each number below is 10 times stronger than the one before it. For example, a ph of 5 is 10 times stronger acid than pH 6. A pH of 4 is 100 times stronger than pH 6. Acids dissolve metals, especially Boiler Iron & Steels.

4. Scale - common limestone deposits, because they block heat transfer when steaming and hold moisture in contact with metal when shutdown. This aids dampness, oxygen and acids in doing their destructive work.

5. The Human Factor - no one would intentionally wreck a good boiler, but there are plenty of folks who are their own worst enemy when it comes to boiler life. The old-time handbooks stated that a boiler in constant and reasonable use will outlast a boiler that is idle. In our era, many boilers are idle most of the time. The best thing you can do is learn and practice the good habits that will result in the best performance, longest life for your boiler and cost savings for you.

BoilerSaver's Corrosion Chemistry 101 To learn more, get The BoilerSaver Book

For that matter, a set of flues takes a considerable chunk of change. Also, every time a set gets cut out and a new set rolled in, it takes life out of the tubesheets.