Chemical Engineering October 2020 - 34

Engineering Practice
Methods For Testing
Steam-Trap Stations
Testing steam-trap stations can be very easy if the plant provides the correct equipment,
training and commitment to the steam-system management program
Kelly Paffel
Inveno Engineering, LLC
IN BRIEF
VISUAL METHODS
TEMPERATURE
METHODS
ESTIMATING STEAM
PRESSURE
IS THE STEAM TRAP
OPERATIONAL?
MEASUREMENT
PROCEDURES
ULTRASOUND
SENSITIVITY SETTINGS
SETUP AND OPERATION
TESTING METHODS AND
RESULTS
FIGURE 1. Shown here is a visual indicator on a steam trap
W
hen it comes to testing steam
traps, a frequently asked
question is, " what is the best
method? " The true answer is to
use all of the technologies available today.
No single test method provides the best results
all of the time for the variety of applications,
installations and steam-trap types
in industrial plant operations. Therefore, all
tools available in the marketplace should
be implemented and used where appropriate.
So, what are these tools? They can be
segmented into three categories:
* Visual
* Temperature
* Ultrasound
Becoming proficient with these tools is
like riding a bicycle - the more you ride
the bicycle, the better you become. Practice
and gaining the knowledge of the
methods is the key to successfully using
the different devices.
VISUAL METHODS
The use of a testing-tee valve arrangement,
testing-valve combination, or an inline sight
glass for reviewing the steam trap discharging
to the atmosphere is a very effective
way of testing steam traps (Figures 1 and
2). This visual method can accurately determine
the following conditions:
* Blow-through steam or a failed open
34
FIGURE 2. A steam trap test valve is shown here
condition
* Severe steam leakage
* Under-sizing
There are some negatives to any testing
method and the visual method is no exception.
The inspector must understand the
concept of flash steam and become aware
of the difference between flash steam and
blow-through steam. There are safety concerns
due to the release of hot steam to atmosphere
during the testing phase. Finally,
there is a small additional cost associated
with installing the components that permit
online testing.
TEMPERATURE METHODS
The relationship between steam pressure
and temperature makes temperature measurement
extremely helpful in understanding
many different operating conditions of steam
components that are found in the steam and
condensate system.
Infrared (IR) temperature measuring is a
very quick and versatile tool for steam systems.
Like all testing equipment, IR requires
training to ensure success. All diagnostic
tools have positive features and negative
attributes. It is important to understand the
negative attributes to ensure an accurate
temperature measurement.
Temperature measurement devices must
be an integral part of a steam-trap station
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Chemical Engineering October 2020

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