ExxonMobil Test ExxonMobil Problem Solving 1 — Questions and Answers
Question 1: A pump's flow rate has dropped 20% below target. Which diagnostic step should be performed FIRST?
- Replace the pump impeller immediately
- Check the suction line for blockages or low inlet pressure (Correct answer)
- Shut down the pump and call maintenance
- Increase the motor speed to compensate
Correct answer: Check the suction line for blockages or low inlet pressure
Checking the suction side for blockages or low inlet pressure is the correct first step, as these are common causes of reduced pump flow.
Question 2: A technician finds that a temperature gauge reads 15°C higher than the adjacent thermocouple. What is the most likely cause?
- The process temperature has genuinely increased
- One of the instruments is faulty or needs calibration (Correct answer)
- Heat is being generated between the two measurement points
- The control system has a software error
Correct answer: One of the instruments is faulty or needs calibration
A significant discrepancy between two instruments measuring the same point most likely indicates one instrument is faulty or out of calibration.
Question 3: During a routine inspection, you notice corrosion forming at a pipe flange. What is the correct initial action?
- Continue operations and monitor the corrosion rate
- Document the finding and report it to the inspection engineer immediately (Correct answer)
- Apply touch-up paint to stop the corrosion temporarily
- Shut down the line and replace the flange immediately
Correct answer: Document the finding and report it to the inspection engineer immediately
Documenting and reporting to the inspection engineer allows a qualified professional to assess the severity and determine the appropriate corrective action.
Question 4: A batch of refined product fails quality testing for sulfur content. Which process unit would most likely be the root cause?
- Atmospheric distillation unit
- Hydrotreater (Correct answer)
- Crude desalter
- Cooling tower
Correct answer: Hydrotreater
The hydrotreater is responsible for sulfur removal; if it malfunctions or catalyst is depleted, product sulfur content will exceed specifications.
Question 5: An operator notices an unexpected pressure drop in a section of pipeline. Which action should be taken FIRST?
- Increase the pumping pressure to maintain flow
- Check for potential leaks, blocked instruments, or valve position changes in that section (Correct answer)
- Shut down the entire pipeline immediately
- Wait 30 minutes to see if pressure stabilizes
Correct answer: Check for potential leaks, blocked instruments, or valve position changes in that section
An unexpected pressure drop must first be investigated by checking for leaks, instrument faults, or valve changes before any corrective action.
Question 6: A plant's energy efficiency has decreased by 8% over three months despite no process changes. What should be investigated first?
- Crude oil grade and quality changes
- Heat exchanger fouling or insulation degradation (Correct answer)
- Changes in market pricing affecting target output
- Shift crew scheduling and overtime patterns
Correct answer: Heat exchanger fouling or insulation degradation
Gradual efficiency loss without process changes typically points to heat exchanger fouling or degraded insulation reducing heat recovery.
ExxonMobil Test ExxonMobil Problem Solving 1
A pump's flow rate has dropped 20% below target.
Which diagnostic step should be performed FIRST?