Instrumentation QC Inspector Course & Interview Questions
1. What are the parts of coaxial cables?
2. What is Junction Box?
An earthed enclosure within which wires or cables can be safely connected
3. What are the Kinds of Metering Instrument?
Conventional electronic and pneumatic transmitter
Resistance Temperature detectors
Instruments air line pressure gage
Turbine positive displacement and magnetic flow meters
Pilot Tube annular flow meters
4. What are the task in performing instrument loop checking?
Conducted as per cable package and markings, Tagging and Wire color coding. Testing to be conducted or using test equipment or hand tools continuity test and referenced loop package documents
Considering to identify the Instruments loop (either Closed Loop or Open Loop)
Obtain Documents pertaining to the process loop in order to understand All devices and their intended functions
Inspect the loop components through visual observation in order to ensure that the components are correctly installed
The prepared approved Instrument loop package or folder shall be always implemented
5. What is instrumentation?
Is a branch of science which deals with measurement and control of process variables such as pressure, flow, temperature, level and etc.
6. What are the kinds of pressure measurement?
Deferential Pressure Instruments
7. What are the Kinds of Smoke Detector?
Air Sampling type detector
Automatic fire detector
Automatic Fire Extinguishing or suppression system operation detector
Electrical conductivity heat detector
Fixed temperature detector
Other Fire detectors
Pneumatic rate-ofrise tubing heat detector
Projected beam-type detector
Radiant sensing fire detector
Rate compensation detector
Rate offrise detector
8. What are the Types of Switches?
Lever actuator limit switch
Liquid level switch
Liquid level flow switch
Nuclear level switch
9. What are the Kinds of Alarm Control Unit?
Fire Alarm Control Unit (Panel)
Intermediate Fire Alarm Fire Supervisory control Unit
Master Control Unit (MCU Panel)
Protected Premises (Local Control Unit Panel)
10. What is the Saudi Aramco Instrument Signal Pair wire color coding?
P – Black
N – White
11. What is the Saudi Aramco Instrument Signal Triad wire color coding?
P1 – Black
P2 – Red
N – White
12. What are Instrument Loop-package Documents Contents?
Applicable design documents
Manufacturer’s documentation needed to test and verify loop operation
Completed quality control RFI checklists and test reports from receiving, installation, and calibration
13. What Items we should to check for Instrument Stand / Supports?
Fabrication of Stand as per drawing
Deburred , Primed and Painted
Instrument location as per IPL Drawing
Access is unobstructed and clear for maintenance
Stand and Support Secure
14. What Items we should to check for Instrument Device Installation?
Instrument Calibrated prior to installation and documentation checked
Instrument mounted in accordance with hook up drawing
Check instrument is correct in accordance with ISS / P & ID
Instrument securely installed on stand
Elevation correct relative to process tapping
Stand and Support Secure
15. What Items we should to check for Instrument Impulse Tubing?
Material used according to specification
Steam tracing and insulation as per hook up
Seal fitting installed and Filled
Isolation and equalization valves / manifold installed
Vent and drain / manifold installed
Tubing slope Checked
Verify Tubing connection to HP & LP sides
Leak Test done
Pressure Test of impulse tubing
16. What Items we should to check for Instrument Cabling / Signal / Conduit?
Check electrical installation with respect to conduits, glands, seals, are correct
Core and cable tagging are meggered and checked
Check connection terminations with instrument for tightness
Instrument installation pressure tested as required
17. What kinds of materials being used for impulse tubing pressure leak testing?
18. What are the test procedures of Pressure Transmitter?
The process connection shall be connected to a dead weight tester Budenberg (Range 1-1200 bar g) or equivalent
The output signal shall be connected to an electronic test meter or precision manometer as applicable
Align equipment at zero
Apply actuating pressure to full range and lock-in signal pressure- check system for leaks
Reset to zero
Apply actuating pressure of 25,50,75 and 100% of range-record readings
Reduce actuating pressure of 75,50,25 and 0 % of range-record readings
When necessary, adjustments according to the manufacturer’s instructions shall be made until the quoted accuracy is obtained
Apply 110% signal as check for hysteresis
Transmitters with indicating scales shall have the indicator calibrated during the above tests and the transmitters color coded
19. What are the specific contents of Material Requisition (MR) in Saudi Aramco?
SCOPE OF SUPPLY
EQUIPMENT / MATERIAL DESCRIPTION
VENDOR DOCUMENTATION REQUIREMENTS
SPARE PARTS DATA PACKAGE
LIST OF ATTACHMENTS
20. In Area Classification what are the difference between Class 1 Zone 0, Class 1 Zone 1 & Class 1 Zone 2 Location?
Class 1 Zone 0 = In which ignitable concentrations of flammable gases or vapors are present Continuously and in which ignitable concentrations of flammable gases or vapors are present for long periods of time.
Class 1 Zone 1 = In which ignitable concentrations of flammable gases or vapors are likely to exist under normal operating conditions or vapors may exist frequently because of repair or maintenance operations or because of leakage and in which equipment is operated or processes are carried on, of such a nature that equipment breakdown or faulty operations could result in the release of ignitable concentrations of flammable gases or vapors and also cause simultaneous failure of electrical equipment in a mode to cause the electrical equipment to become a source of ignition.
Class 1 Zone 2 = in which ignitable concentrations of flammable gases or vapors are not likely to occur in normal operation and if they do occur they will exist only for a short period or in which volatile flammable liquids, flammable gases, or flammable vapors are handled, processed, or used, but in which the liquids, gases, or vapors normally are confined within closed containers of closed systems from which they can escape, only as a result of accidental rupture or breakdown of the container system and in which ignitable concentrations of flammable gases or vapors normally are prevented by positive mechanical ventilation, but which may become hazardous as a result of failure or abnormal operation of the ventilation equipment.
Instrumentation Interview Questions
1. What are the types of Instrumentation circuit’s cable requirements for NEC Article 725 Class 1 Circuits?
Ans. Twisted Pair, Type TC Cable Armored, Type MC or Equivalent
2. What are the types of instrumentation circuit cable requirements for NEC Article 725 Class 2 and 3 Circuits?
Ans. 300 V. PLTC/ITC Single twisted pair or Triad Cable armored
3. What are the required Susceptibility levels of signal wiring instrumentation cable?
Ans. 1 or 2
4. What is the required minimum spacing for the routing of instruments and control cabling (Level1 or 2) is always maintained between the cables and the devices like source of strong electromagnetic fields such as large transformer, motor and generators?
Ans. 2 Meters
5. How many minutes required while conducting pressure leak test at all impulse tubing?
Ans. 30 Minutes
6. What is MOV?
Ans. Motorized Operated Valve
7. What is GOV?
Ans. Gas Operated Valve
8. What are the motor nominal external control voltages shall be as specified in 8020-718-Engineering (34-SAMSS-718 Sec. 126.96.36.199)?
Ans. 24 VDC, 125 VDC or 120 VAC
9. What is P&ID?
Ans. Piping and Instrument Diagram
10. What is ILD?
Ans. Instrument Loop Diagram
11. What is the minimum direct burial requirements of an Fiber Optic Cables FOC without any required protection as per Saudi Aramco Standard?
Ans. 1200 mm.
12. What is the minimum direct burial requirements of an Fiber Optic Cables FOC in rock areas, when placed inside concrete encased conduit as per Saudi Aramco Standard?
Ans. 250 mm to 760 mm