QM- Heat Trace Flashcards
What is the purpose of the QM system?
Maintain given temperatures associated with special processes. These processes contain fluids in pipes, tanks, valves, and pumps that require a maintained heat control in order to prevent precipitation of concentrated material in the fluids
What systems/components use heat tracing?
Boric Acid Batch Tank, RMWT piping, Holdup tank piping, RWT piping, RU-141/143 piping, Hydrogen Analyzer System, Solid Radwaste system, Liquid Radwaste System Evaporator, and BAC
What kinds of cables are used in the QM heater elements in systems maintained under 200F?
Self-limiting parallel cables
What QM cables are used for systems requiring >200F?
Mineral Insulation cables
They are series connected resistive elements embedded in mineral insulation within stainless steel jackets
What failure warnings are on the Heat Tracing panels, not directly on the controllers?
Heater element failure light which energizes on heater circuit power failure or heater continuity failure for MI cables and heater continuity failure for self-limiting heaters
Fan failure light for panels requiring cooling fans
Panel alarm annunciator and light for high or low temperature, heater element failure, or fan failure.
Audible alarm may be silenced manually
What is the overall system’s temperature controllability band?
+/- 2.5F from controlled setpoint
How is the plant affected by a loss of heat tracing?
Hydrogen monitor heat tracing loss puts us in a TRM
For boric acid systems there is a possibility that the lines may rock up
(boron comes out of solution and starts to solidify)
Regarding the QM system, what is the purpose of the step-down transformers?
Each step-down transformer supplies power to a control panel by stepping down the voltage from
a 480 VAC MCC power supply to 120 VAC and is located near its associated control panel.
Regarding the QM system, what is the purpose of the control panels?
Control and distribute heater element power.
Monitor and display the temperature levels of the heated system.
Monitor heater continuity and power supply.
Annunciate and indicate alarms.
Integrate alarms for each panel into one common alarm in the control room.
Regarding the QM system, what instrumentation is provided for the modular solid state controllers on the control panels?
Temp. setpoint
Temp. deviation
high alarm light
low alarm point
heater “on” light
Where are the heat tracing lines ran on the applicable subsystems?
along pipes, etc. under the insulation
What is the white neutral return wire in the heat tracing lines for?
monitoring the continuity of the heater circuit
In the QM system, what is the purpose of the temperature sensors located on the heat traced lines?
provide an input signal to its associated panel mounted controller
controller displays the line temperature and compares the line temperatures to the set high and low temperature points
When the line temperature drops
below the set point the controller energizes solid state relays or contactors which supply power to
the heater element
Where are the outdoor Q-class piping sections of QM heat tracing supplied power from? What about the tracing sections for the hydrogen analyzer?
NH
PH
When validating a low
temperature alarm for the QM system, What determination should be made?
if it is due to system flow or heater malfunction
