you should use, and the maximum limit or range. Notice
also that some of the test frequencies say "as required."
For your ship's boilers to operate safely and
This means the affected sampling locations have
efficiently, you must pay careful attention to the quality
of the boiler water. Your responsibilities for sampling
feedwater at these locations, you will compare the
boiler water will vary based upon the condition and
chemical test results with the meter reading. The
operation status of each boiler. In the following
required sampling frequently for each of these locations
paragraphs, we will talk about some of the more
will depend upon the chemical test comparison results.
common conditions you will encounter.
For example, if the chemical chloride test result is more
than 0.02 epm higher than the meter reading, the test is
STEAMING BOILERS.-- You should sample
unsatisfactory and the meter is faulty. If the chemical
boiler water from a steaming boiler at the following
chloride test result is less than the meter reading by more
than 0.02 epm, then the water must be tested for
1. Within 30 minutes after the generator is started.
hardness. If hardness is less than 0.02 epm than the
meter reading, then once again the meter is faulty. In this
2. As often as you need to maintain the chemical
case, you must sample at that location at least once every
limits, or at least every 8 hours. The time
4 hours until the indicator is brought back into service.
between samples should not exceed 8 hours.
Remember, many waste heat boilers are not equipped
3. Within 1 hour before starting blowdowns.
with a sample connection at the condensate cooler or the
control condenser. In these cases, you should compare
4. Between 30 to 60 minutes after blowdowns.
the applicable standards to a feedwater tank sample.
5. Between 30 to 60 minutes after batch chemical
6. Within 1 hour before the generator is secured.
Heat System (FFG-Class Ships)
When taking samples from a steaming boiler, keep
the design of the system in mind. The water and steam
the water sampling requirements for an FFG-class ship's
mixture you will sample originates from the boiler. The
service diesel generator and waste heat system. First,
water then passes through a cooler which lowers the
let's talk about the treatment chemical you will be
water temperature to 100°F (37.7°C) or below. Each
sampling and testing, Nalcool 2000.
boiler has its own cooler. For this reason, you must
designate and maintain a separate sample bottle for each
NACOOL 2000.-- Nalcool 2000 consists of a blend
boiler. You should also follow all the safety precautions
of corrosion-inhibitor chemicals in a water solution. The
listed at the beginning of this chapter.
major components of Nalcool 2000 are sodium nitrite,
sodium borate, sodium silicate, and an organic copper
IDLE BOILER.-- In sampling boiler water from an
inhibitor. Sodium nitrite helps to forma protective oxide
idle boiler, you will use the same locations you would
layer on ferrous metal surfaces. Sodium borate is an
use for a steaming boiler. For an idle boiler, however,
alkaline buffer that reduces corrosion by neutralizing the
you will only be required to sample 1 hour before a
acidic by-products that result from combustion blow-by
blowdown, usually after the boiler is secured. Even if an
gases leaking into the coolant. Sodium silicate forms a
idle boiler has been blown down, you will not be
silicate film on metal surfaces and provides effective
required to sample it either after the blowdown or before
corrosion protection for mixed metal systems. The
the subsequent start-up.
organic copper inhibitor chemically bonds with the
copper in copper alloys, resulting in a protective layer
on the surface.
The sampling requirements and standards for
DIESEL JACKET WATER SYSTEM.-- To
feedwater will vary based upon each specific type of
monitor the diesel jacket water system of an FFG-class
water, contaminant, or test, and the associated standards,
ship, you should take samples at the following times:
limitations, and required intervals. Many of the
After freshly filling and treating the system
sampling and testing requirements for feedwater are
shown in table 2-1. Notice how the table shows you the
After adding water to the cooling system
water type, the required sampling intervals, the
contaminate for which you are testing, the type of test
After adding chemicals to the cooling system