CPA Equipment Maintenance & Operations 3 — Questions and Answers
Question 1: What is the function of an expansion loop or expansion joint in a petroleum pipeline system?
- To increase pipeline flow capacity
- To absorb thermal expansion and contraction of the pipe (Correct answer)
- To reduce pipeline pressure
- To separate water from crude oil
Correct answer: To absorb thermal expansion and contraction of the pipe
Expansion loops and joints accommodate dimensional changes in piping caused by temperature variations, preventing stress and potential pipe failure.
Question 2: A positive displacement pump differs from a centrifugal pump primarily because it:
- Can only handle clean fluids
- Delivers a fixed volume of fluid per revolution regardless of pressure (Correct answer)
- Operates at much higher speeds
- Does not require a motor to operate
Correct answer: Delivers a fixed volume of fluid per revolution regardless of pressure
Positive displacement pumps move a fixed volume per stroke or revolution, making their output relatively independent of discharge pressure.
Question 3: During a compressor oil analysis, a high silicon content reading typically indicates:
- Normal compressor wear
- Air filter failure or bypassing (Correct answer)
- Overheating of the compressor
- Water contamination in the oil
Correct answer: Air filter failure or bypassing
Silicon is a major component of airborne dirt; elevated silicon in compressor oil indicates that the air filter has failed or air is bypassing the filter.
Question 4: What is the purpose of a 'bump test' when starting a motor-driven pump for the first time after maintenance?
- To test the motor's current draw under load
- To verify correct rotation direction before full operation (Correct answer)
- To prime the pump with process fluid
- To check alignment under operating temperature
Correct answer: To verify correct rotation direction before full operation
A bump test briefly energizes the motor to confirm it rotates in the correct direction, preventing damage from reverse rotation.
Question 5: Which instrument is used to measure the thickness of a pipe wall to detect corrosion without cutting into the pipe?
- Manometer
- Ultrasonic thickness gauge (Correct answer)
- Vernier caliper
- Micrometer
Correct answer: Ultrasonic thickness gauge
An ultrasonic thickness gauge sends sound waves through the pipe wall and measures the return signal to determine wall thickness non-destructively.
Question 6: A storage tank is equipped with a floating roof. What is the PRIMARY advantage of this design?
- It allows inspection without shutting down the tank
- It minimizes vapor space to reduce evaporative losses and fire risk (Correct answer)
- It prevents water from entering the tank
- It keeps the stored product at a constant temperature
Correct answer: It minimizes vapor space to reduce evaporative losses and fire risk
A floating roof rises and falls with the liquid level, virtually eliminating the vapor space above the product to reduce evaporation and explosion risk.
Question 7: When replacing a control valve actuator, what is the correct procedure for setting the valve positioner?
- Set positioner to 50% and leave it fixed
- Calibrate using the full input signal range (e.g., 4–20 mA) to match 0–100% valve travel (Correct answer)
- Manually operate the valve a few times to break it in
- Set the positioner only after the valve is back in service under full process pressure
Correct answer: Calibrate using the full input signal range (e.g., 4–20 mA) to match 0–100% valve travel
Proper positioner calibration requires applying the full input signal range to verify the valve travel matches the signal from fully closed to fully open.
CPA Equipment Maintenance & Operations 3
What is the function of an expansion loop or expansion joint in a petroleum pipeline system?