Module 9: Control Techniques - International Association of Fire ...

Student Text IAFF Training for Hazardous Materials: Technician©
are for background information only. Do not attempt
these procedures unless you have been thoroughly
trained.
To inspect damaged pressure cargo tanks:
1. Examine all accessible surfaces for cracks, scores,
gouges, and dents. Pay close attention to these types of
damage that occur in the longitudinal direction.
2. Look for cracks on the tank. Relatively large cracks are
visible to the naked eye. For smaller cracks, the use of
a dye penetrant may be necessary. Since material often
seeps through even small cracks, look for signs of
frosting or clear liquid on the tank surface.
3. For each dent:
• Identify dents that have scores or gouges associated
with them and those that cross a weld. (Dents with
scores or gouges and/or dents that cross welds are
the most dangerous.)
• Examine each point of minimum curvature for
cracks and, using a dent gauge, measure and record
the curvature of all dents, no matter how small.
4. For each score or gouge:
• Measure the depth of each score or gouge on the
tank to determine the extent of damage and risk.
• Identify where each score or gouge crosses a weld.
• Note when a score or gouge crosses a weld and
measure the depth of the removed weld metal.
(When a score or gouge crosses a weld, the damage
is more critical if it removes the weld’s base metal
rather than just the weld reinforcement.)
• When a score or gouge crosses a weld, determine if
the “heat affected zone” adjacent to the weld has
been damaged. (If the score or gouge has damaged
the heat-affected zone, the damage is potentially
critical.)
5. Determine the temperature of the tank metal by
attaching a thermometer to the shell of the tank; or, if a
tank is equipped with a thermometer, check the thermometer
well.
Module 9: Control Techniques 9-33