Page 444 - Boiler_Operators_Handbook,_Second_Edition

Chapter 12

Why They Fail

National Board of Boiler Inspectors advised the board
When a boiler or related equipment fails it’s usu- in 2003 to not publish that information because they
ally due to a lack of attention. While modern control might be subjected to a lawsuit regarding it. I consider
systems normally manage to ensure a failure in a safe it shameful because the public has no other source for
manner, i.e. a shutdown, the news media frequently information regarding boiler accidents. I can only hope
has headlines involving catastrophic failures. Some of that the trend to fewer accidents is continuing and that
those catastrophes involve human suffering and death. this book is contributing to that trend.
Although not at the frequency and numbers of a century Boilers seldom wear out. The effects of wear that
ago it still generates grave concerns when an incident you associate with machinery and automobiles are no-
does occur. where near as significant with boilers. Most of the time
the boiler just sits there. There is rubbing associated
with movement as it heats up and cools down but, in a
WHY THEY FAIL normal plant, it doesn’t happen often enough to be im-
portant. Don’t confuse the boiler with the burner. They
A Little Bit of History really are separate items. I will admit that burners wear
The last year of the twentieth century was a disap- because there are so many moving parts associated with
pointing one for those of us who believed we were mak- most of them.
ing a difference in the industry. Despite maintaining an I’ve worked on many a boiler that was over fifty
average of less than ten people killed by boiler accidents years old and had no evidence that it was nearing the
1999 produced 21 deaths. Six died in what has been end of its life. I recently provided engineering assistance
described as the most expensive single accident ever; to rebuild three boilers that were thirty years old and
by itself bearing losses in excess of one billion dollars. will undoubtedly last another thirty. Boilers usually fail
Despite the horror of September 11, 2001, (which wasn’t by incident and the most common incidents have to do
an accident) a boiler explosion holds the record for the with lack of, or improper, water treatment.
most deaths from a single accident.
It happened in 1865, at the end of the Civil War, Water Treatment
shortly after Lee surrendered to Grant. Over 1900 union Improper water treatment or the lack of it contrib-
soldiers clambered aboard the riverboat Sultana head- utes to most of the failures that I have encountered. The
ing north to Cincinnati. Shortly after leaving the dock boiler fails because scale builds up until some metal
the boilers exploded. Some died immediately, others overheats, the metal fails to allow the steam and water
suffered from burns and shrapnel wounds until suc- to escape where the water then flashes into steam so
cumbing weeks later. About 1800 people, including quickly that it violently blows the boiler apart.
women and children, died in that accident. With little There’s a whole chapter in this book on water
left of the ship the actual cause remains undetermined. treatment and opportunities for you to learn more at the
In the early 1900’s thousands died each year from treatment supplier’s school or other sources. If a boiler
boiler accidents. That’s why the ASME proceeded to operator is comfortable with his water treatment, the
produce the boiler construction codes at the beginning likelihood that the boiler will fail is very low.
of the twentieth century. The dramatic improvements
that reduced injuries up until the end of that century
should continue but 1999 started a new trend. LOW WATER
Recent history is depicted by the charts in Figure
12-1 and Figure 12-2 which show the swing in primary For years we could count on the reports of boiler
cause from low water to operator error and poor main- failures to list low water as the primary reason the boiler
tenance plus an increase in incidents. You’ll notice the failed. Even today, with special systems and all our
data are very old. That’s because the lawyers for the knowledge, low water always stands out as a significant

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