Inspection and Quality Control Questionnaires

Q. What is QA/QC?

QA/QC means, “Quality Assurance/Quality Control” the purpose of this (QA/QC) is to establish the sequence of requirement for the quality of material, quality of works, its inspection and records.

Q. What are basic responsibilities of QA/QC personals?

To ensure execution of works and comply fully as per standard and approved specs.

Q. What are the basic required documents for a QA/QC personal?

The basic required documents QA/QC personal are as following:

ITP: to conduct the Quality check (inspection/witness/surveillance) etc.

QCP: Quality Control Procedure

WP: standard procedure to execute the works. (Work Procedure)

P&ID: as a reference to ensure that the work is as per standard drawing.

MTC: To ensure that the material complies the PES standard specs.

PP: To ensure that the Instruments are installed as per P&ID and PP as per convenience.

IDS/ISS: To ensure that the instrument comply with the basic requirement.

RFI: To conduct the inspection of completed works. (Request for Inspection)

QR: To maintain the quality records of completed works etc.

QCO: To issue a warning in case of little violation and observation

NCR: To issue a warning in case of serious violation of standard. (Non Compliance Report)

Calibration Report: To ensure parameters are function checked as per IDS.

Hook Up: To ensure that the remote connection of pneumatic is done correctly.

Wiring Diagrams: To ensure that the wiring is done correctly.

Q. What are QA/QC’s ITP’s and QCP? Give a brief.

ITP: This procedure informs about the kinds of quality check (surveillance, inspection, witness or hold points) means quality of work being done in proper sequences.

QCP: This procedure address the activities and requirement in details

Q. What is NCR? Why does it need for a QA/QC personal?

NCR means Non Compliance Report or non conformance report, QA/QC personal has reserve the right to issue a warning if
the contractor doesn’t comply or violate with the standard procedure.

Q. What are the general work procedures (WP)?

The general sequence of activities will be as follows:

a) Receiving Drawing and Documents

b) Reproduction of Drawings

c) Issuing of Drawing to site

d) New‐Issuing New Revisions

e) Shredding of Drawings

f) Redlining Drawings

g) Transmittal of redlines to Client (As‐built)

h) Restricted access to the DCO

i) Work Permit prior to start the works

j) Record

Q. What are common PPE required? Give a brief.

Following are the common PPE for a safe and quality works‐standard procedure:

Qualification : Awareness about all kinds of safety standard/codes and work procedure.

Experience : Qualified for the works execution.

Use (PPE) : Proper equipment’s and tools shall be used to avoid injuries/loss.

Safety Shoes, Helmet, Glass, Gloves, Earplugs, Harness proper tools and certified equipment’s.

Q. What is redlining? Brief its color coding.

In case of any change occur to the standard approved drawing while the project is being constructed or tested the relevant drawing will be “redlined”. Following color coding shall be used for this purpose:

Red : If any addition required in the drawing.

Green : If any deletion is required from the drawing.

Blue : if any comment is added.

Q. What are the difference between Inspection (Surveillance), witness and Hold point?

Inspection : Work can be execute without clients inspection and it can be Inspect some part of them if it required.

Witness : Work can be execute without client inspection and then it can be inspected upon the completion of work.

Hold Point : Work can’t be executed without client inspection.

Q. What is difference between Hazardous and Non Hazardous area?

Hazardous: A Hazardous location is defined as an area where a potential for fire or explosion exist due to the presence of flammable gases, liquid or vapors, combustible dusts or fibers and flying in sufficient quantities to produce a n explosion or ignitable mixture.

Non‐Hazardous: An area where no risk of presence of any kinds exposition.

Q. What are different kinds of certification?

i) Weather Proof

ii) Dust Proof

iii) Water Tight

iv) Explosion Proof

v) Flame Proof

vi) Intrinsic Safety Proof

Q. What is ISO? Explain some of its standards?

ISO means International Standard Organization; some of the standards are ISO 9001 QMS, ISO 14001, ISO 27001 etc.

Q. What are Zone classifications? Give a brief.

Zone classification is defining the area of hazards, they are as below;

Zone – 0: A zone in which explosions gas/air mixture is continuously present or present for extended periods, during normal operation.

Zone – 1: A zone in which explosions gas/air mixture is likely to occur in normal operation.

Zone – 2: A zone in which explosions gas/air mixture is not likely to occur in the normal operation and if it occurs, it will only exist for a short time.

Zone – 10: A zone in which explosive dust atmosphere is present continuously or for extended periods of time.

Zone – 11: A zone in which there is likelihood that explosive atmosphere may occur for short periods due to unsettled dust layers.

Q. What are the standard heights to install the instruments?

A standard height to install the instruments is 1‐4 meters, but it can vary less or more as per location’s convenience.

Q. What is Loop – Check?

To ensure that the system wiring from field to control console functioning.

Q. Explain tuning of controller; (a) Closed Loop Method, (b) Open Loop Method.

Tuning basically involves adjustment of α+I+D parameters to achieve good control. The gain, time, constants & dead time around the loop will dictate the settings of various parameters of controllers.

a) Closed Loop Method : Ultimate gain method

b) Open Loop Method : process reaction curve

Q. What are area classifications? Give a brief.

As per NEC and NACA, following are the hazard classification;

Class I : Location in which flammable gases or vapors may be present in the atmosphere in quantities sufficient to produce explosive or ignitable mixture.

Class I gases/vapors are divided into four following groups

Group A: Presence of Acetylene

Group B: Presence of Hydrogen, Butadiene, Ethylene Oxide etc.

Group C: Presence of Ethylene, Cyclo‐Propane, Carbon‐Mono Oxide etc.

Group D: Presence of Gasoline, Acetone, Butane, Propane, Alcohol, natural gas (Methane) etc.

Class II : Location in which the presence of combustible dust are in the air in sufficient quantity to ignite or explode.

Class II conductive/non‐conductive dust is divided into three as below:

Group E: Presence of metal dusts (Aluminum, Magnesium and chemical dusts etc).

Group F: Presence of black carbon, charcoal, coal or coke dusts etc.

Group G: Presence of non‐conductive dust (foam, starch, combustible plastic etc).

Class III : Location in which easily ignitable fibers or flying are present but are not likely to be in suspension in air in quantities sufficient to produce ignitable mixture.

Division – 1 : The Hazards are present continuously or periodically under normal operation condition.

Division – 2 : The Hazards are only presents during accidental or abnormal conditions.

Q. Why is flow measured in square root?

Flow varies directly as the square root of D.P (Differential Pressure) since this flow varies as the square root of the D.P the pen does not directly indicate flow. The flow can be determined by taking the square root of the pen. Say the pen reads 50% of chart.

Q. What is the diameter of the transmitter nozzle?

0.030”

Q. How will you work/remove on a control valve which is in line?

Inlet and outlet discharge manual valve to be closed by the operator and tagged.

The valve No. 1 to be closed first. Control valve should be in fully open condition.

Valve No. 2 closed. Secondly the line has to be drained and depressurized before removing.

Q. What are the standard nozzles orientations for process control systems?

 

Q. What is different between Open Loop and Close Loop?

Open Loop : A Loop System which operates direct without any feedback and generates the output in response to an input signal.

Close Loop : A loop system which uses a measurement of the output signal through feedback and a companion with the desired output to generate an error signal that is applied to the actuator.

Q. What is feedforward and feedbackward control system?

Feed‐forward control is a system in which corrective action is based on measurement of disturbance inputs into the process.

Feed backward control involves the detection of the controlled variable & counter acting of changes in its value relative to setpoint by adjustment of the manipulated variable.

Q. What is Logic Gate?

A Digital logic circuit with one or more input voltage but only one output voltage.

Q. What does a transmitter O/P signal start from 315 or 420 m.a.?

Linear and can check up weather its “live zero” or “dead zero”

Q. Why is M.A. signal preferred for signal transmission?

Noise reduction and no current drop for long transmission lines.

Q. Explain Cascade control (To prevent outside dist.)

Cascade means two controllers in series, one of them is a matter of primary & the second is the
secondary or slave. The O/P of the slave controller operates the final control.

Q. Explain three element feed water control system.

Q. What is Foundation Field bus system?

A fully digital control system is called Foundation Field bus system.

Q. What are meant FAT, SAT, RAT?

FAT : Factory Acceptance Test

SAT : Site Acceptance Test

RAT : Run Acceptance Test

Q. What is Microprocessor Control System? Give a brief of PLC, DCS and SCADA?

Computer based control system is called Microprocessor control system. The brief of PLC, DCS and SCADA are as following:

PLC : Programmable Logic Control system

PLC’s are used in practice with the aim of achieving higher degree of availability or fault tolerance. The types are as follow:

Fault Tolerant: 1 out of 2 objective systems objective: Reduce the probability of losses of production by switching to a standby system.

Fail Safe: 2 out of 2 system objective: Protect life, the environment and investment by safely disconnecting to a secure “off” position.

DCS : Distributed Control System.

SCADA : Supervisory Control And Data Acquisition.

Q. What are inspection points for a cable tray installation?

Material check as per approved spec, size and type, trays hook‐up, proper distance structure, tray to tray i.e. power/control/signal/low voltage and high voltage, support and fixed strong not shaking.

Q. What are inspection points for field instruments with impulse tubing?

Material inspection as per approved spec material, type and size, installation as per Hook‐up, check line route to avoid any obstruction, check tube bending and check tube support, compression fitting of ferrules and then test (Hydro‐static test) shall be done.

Q. What are inspection points for cable laying?

Material inspection as per approved materials, type and size, meggering, cable routing drawing, completion of cable route (tray, conduit or trench etc) and cable numbering (tags), cable bending, use of proper tools and equipment for cable pulling.

Q. What are inspection points for Junction Box and Marshalling Cabinets?

Material inspection, type size as per approved specification, installation hook‐up for frame, bracket or stands, fixed properly means shaking free, Name Plate and Tag No.

Q. What are standard methods of Ferrules addressing to and from a Junction Box?

For to side only Terminal’s Address required which shall be close to terminal either side and
complete information shall be off from side after or before as per left and right side.

Q. What are standards of installing a DP Transmitter in gas service and why?

Inst. (DP Transmitter) in gas service shall be above the process to avoid the malfunctioning and
drain the liquid (condensate) into the process line easily.

Q. Explain why shield of signal cable is not earthed on both sides?

To avoid the current noise (Resonance)

Q. How do you determine the correct installation of flow orifice?

The orifice data tag shall be punched in the upstream of orifice, the data (tag) side shall be in the upstream of flow direction.

Q. What is RFI? When and RFI will be raised?

Request for Inspection (RFI), RFI shall be raised only when the status of the preliminary inspection satisfactory, and the works (items) or Hold or Witness Points.

Q. What is final RFI? When it shall be raised up?

When the QA/QC department of contractor is satisfied that the work detailed in the construction RFI is completed then request submitted for inspection to the client QA/QC department.

Q. What are the required documents for an inspection?

Following are the required documents for an inspection:

• RFI (Request for Inspection)
• P&ID for line inspection
• PP for location
• Wiring diagram for wiring details.
• Data Sheet for calibration and pressure test.
• Hook‐up etc. for remote tubing/air line
• QR for maintaining record.
• WP (Work Procedure) to check each and every step as per spec.
• QCO for issuing in case of little violation.
• NCR (Non Compliance Report) for issuing in case of major violation etc.

Q. What are the required documents for a Remote Loop folder?

Following are the required documents for a Remote Loop folder:

• Loop package Check list
• ILD (Instrument Loop Diagrams)
• Instrument Loop Acceptance record (TR/Test Record)
• P&ID (Piping & Instrumentations Diagram)
• ISS/IDS (Inst. Spec Sheet/Inst. Data Sheet)
• Alarm List
• Calibration Record (TR)
• Cable Megger Report (Primary Prior to Pulling)
• Cable Megger Report (Secondary after Pulling)
• Pressure Test Record (TR)
• MC Check Record (Remote Loop) (Green Color)
• MC (Marshalling Cabinet) Punch List
• Loop Check Punch List

Q. What are the required documents for a Local Loop folder?

Following are the required documents for a Remote Loop folder:

• Loop package check list
• ILD (if not mechanical loop)
• Cable Megger Report (Primary Prior to Pulling) if not mechanical loop.
• Cable Megger Report (Secondary after Pulling) if not mechanical loop.
• Alarm Loop (If not Mechanical Loop)
• P&ID
• ISS/IDS
• Calibration Record (TR)
• Pressure Test Record (TR) if required
• MC Check Record (Local Loop) (Green Color)
• MC Punch List
• Visual Check Punch List/Loop Check Punch List.

Q. What are the previous levels of inspection? Explain
They are as following:

Level of Inspection for Material

a) Level 0 : Documents requirements only, no Inspection

b) Level 1 : Inspection prior to shipping

c) Level 2 : Minimum requirements, pre‐inspection meetings, one or more unspecified “in progress” surveillance visits.

d) Level 3 : Same as level 2, except that “in progress” surveillance inspection shall be in regular basis.

e) Level 4 : Resident Inspector continuously monitors the works.

Level of Inspection for construction phase:

Hold Points (H) : The inspection activity will not proceed without the presence of Inspector.

Witness Points (W) : Inspection activities can be proceeding after issuing RFI.

Review (R) : Verification of documentation (NMR) on its correctness as per spec and approved drawings.

Surveillance (S) : Inspector has right to conduct random inspection of works.

Inspect (I) / Perform (P)/ : Construction can proceed to next phase without client Test (T) inspection.

Q. What is ITP’s? What are hold and witness Points?

ITP means “Inspection and Test Plan” details of work scope and required types of Inspections.

Hold Point (H) is the level of inspection that client inspection must required through RFI and cannot be proceed until inspection is done by client.

Witness Point (W) is the level of inspection that inspection activity can be preceded without client inspection or client is not available as per RFI timing.

Q. What is schedule Q?

Schedule Q is an attachment to the contract, which is the provision of Quality Assurance and Control, Inspection and Test Plan.

Q. Explain ratio control (Fuel to Air Ratio control of Furnace Diagram?)

Q. Analogue integrator & analogue differentiator?

Q. What is absolute pressure?

Absolute pressure is the total pressure present in the system?

Absolute Pressure = Gauge Pressure + Atm. Pressure

Q. What is absolute zero pressure?

Absolute zero = 760 mm Hg.

Q. What is maximum vacuum?

The maxmm. Vacuum = 760 mm Hg.

Q. What is Vacuum?

Any pressure blow atmospheric pressure is Vacuum.

Q. What are the primary elements for measuring pressure?

The primary elements for measuring pressure are:

1. Bourdon Tube
2. Diaphragm
3. Capsule
4. Bellows
5. Pressure Spring

The above are known as elastic deformation pressure elements.

1. Types of Bourdon Tubes.
1) ‘C’ Type.
2) Spiral
3) Helix

2. Diaphragm : The diaphragm is best suited for low pressure measurement

3. Capsules : Two circular diaphragm are welded together to form a pressure capsule. Material used are PHOSPHER BRONZE, NI‐SPONGE, STAINLESS STEEL.

4. Bellows : Bellows is a one‐piece, collapsible, seamless metallic unit with deep folds formed from very thin walled tubing.

5. Pressure Spring : Pressure springs of helical or spiral shape are used for measuring high pressures.

Q. How will you change the action of a control valve?

If the control valve is without bottom flange the actuator needs to be charged. If the bottom flange is provided, disconnect stem, separate body from bonnet. Remove the bottom flange and the plug from body.

Detach the plug from the stem by removing the pin, fix the stem at the other end of the plug and fix the pin back. Turn the body upside down.

Connect it back to the bonnet after inserting the plug and stem. Connect back the stem and couple it. Fix back the bottom flange. Calibrate the Valve.

Q. What is feedback & feedforward control?

Feedback control involves the detection of the controlled variable & counter acting of changes in its value relative to set point by adjustment of the manipulated variable.

Feedforward is a system in which corrective action is based on measurement of disturbance inputs into the process.

Q. Explain furnace draft control.

When both forced draft & induced are used together at same point in the system the pressure will be the same as that of atmosphere. Therefore the furnace pressure must be negative to prevent hot gas leakage. (0.1” H2O)

Q. How will you apply wt­test calibration to a leveltrol?

Normal Leveltrol
1. Adjust the zero to get 0% output.
2. Connect a transparent PVC tube to the Drain point as shown in Hook‐up.
3. Fill it to the centre of top flange.
4. Adjust the Sp. Gravity or the Span adjusts.
5. Fill it up to 50% to check linearity.
Loss of wt. at 0% = wt. of the displacer
Loss of wt. at 100% = (wt. of the displacer – volume) x σ
i.e. Volume = πr2h σ = Sp. Gravity.

Q. What are the limitation of leveltrol?

72”.

Q. What will happen if the displacer has fallen?

If the displacer has fallen, the output will be maximum. Has a hole in it, the output will be minimum.

Q. How will you check zero of a DP level transmitter?

Close both isolation valves on LP leg and HP leg, equalize, check and adjust zero if necessary.

Q. What is meant by term “EXPLOSIONPROOF”?

Equipment designed to withstand an internal explosion and to prevent the ignition of GAS/VAPOR outside the enclosure.

Q. How many zones are there in class Ι atmospheres?

Three (3) zone 0, zone 1, zone 2.

Q. How many groups or gases/vapors are there in ClassΙ atmosphere?

Division : Four A, B, C, D

Zone : Three ΙΙC, ΙΙB, ΙΙA

Q. What type of conduit must be used within Class Ι zone 0/1 area?

Threaded Rigid Metal Conduit.

Q. How many threads must be engaged to make a joint EXPLOSIONPROOF?

5 Full Threads NEC 501‐4 (A) (1) requires threaded connection to be made up with at least 5 threads fully engaged.

Q. What is the distance from an EXPLOSIONPROOF enclosure must a seal be installed?

18” NEC 501‐5 (A) (1) conduit seals shall be installed within 18” of the enclosure.

Q. In a ClassΙ. Zone 0 areas A 2” conduit is terminated to an enclosure containing only terminals is a conduit seal is required.

Yes. NEC 501‐5 (A) (1) (B) entries 2” and larger into enclosures containing terminals, splices or taps sealing fittings are required.

Q. Why are sealing fittings installed in conduit systems?

To minimize the passage of gases/vapors and to prevent the passage of flames into the conduit systems can also be used to drain conduit.

Q. What is the maximum distance a sealing fitting is installed from boundary location?

10 FEET NEC 501‐5 (A) (4) and (B) (2) requires sealing within 10 Feet either side of the boundary.

Q. What is the minimum thickness of the compound inside a sealing fitting?

The minimum thickness shall not be less than the trade size of the sealing fitting and in no case less than 5’8 inch 501‐5 (C) (3).

Q. Explain what is meant by the term “FLASH POINT” of liquid.

The minimum temperature at which a liquid gives of a sufficient concentration to form an ignitable mixture.

Q. A conduit outlet box can be used as a sealing fitting when fitted with sealing cover?

Yes. A GU Type fitting can be used as a sealing fitting when fitted with a sealing cover.

Q. What is the ratio of mix powder to water?

2 parts of powder to 1 part of water (WATER : must be sweet water)

Q. What is the purpose of FIBER DAM inside a sealing?

To make a foundation for the compound. The fiber dam must be strong enough and tight enough to prevent the weight of the poured compound from seeping out from the conduit.

Q. What is the minimum information required on a classified area drawing.

1. Differentiation between the classified and non‐classified locations.
2. Minimum AIT (Auto Ignition Temperature) of the gas/vapor.
3. Differentiation between the groups.
4. Classified areas to be shown in plan and elevation

Q. What is the maximum internal and external surface temperatures allowed in class I Zone 2 areas?

800° of the Auto Ignition Temperature of the gas/vapor in the area.

See NEC: 501‐5 (A) (1); 501‐5 (A) (4)……………………………………..

Q. Where a mixture of gases has a mixture density less than 75% of the density of air what is it classed as?

Lighter than air. See SAES –B‐068, Para 5.4

Q. The mixture of gases/vapors of different ignition temperatures. How is the ignition temperature of the gas/vapor defined?

By one of three methods ………………….. See SAES B‐068, Para 5.3

1. Lowest individual temperature of the mixture.
2. Test of the mixture
3. By calculation.

Q. What is the classification of an unventilated room?

ClassΙ Div. 1 Group A / Class Ι Zone 1 Group ΙΙC

Q. Are sealing fittings required for smart transmitters in a ClassΙ Zone 2 area?

No. smart transmitters have a low wattage output and usually will not reach 80% of the auto ignition temperature of the gas/vapor, also the cable is terminated within a terminal chamber which is separate from the process by a minimum of two seals.

Q. What is the maximum %age of cross­section a conduit can be filled containing three(3) or more wires?

40% as per NEC Ch. 9 Table 1.

Q. What is PVC in cable insulation an abbreviation for?

Poly Vinyl Chloride

Q. What is the purpose of drain/shield in instrumentation wires?

To reduce electrostatic noise and unwanted voltage.

Q. Per Aramco Standards, what is minimum separation between low voltage power cables and instrumentation cables in cable trays.

Minimum “300 mm.”

Q. Per NEC, what is the maxm. Distance between supports for 2­inch rigid steel conduit.

As Per NEC Article –Table 344:30 (B) (2)

Horizontal : 4.9 mtrs. (16 Feet)

Vertical : 6 mtrs.

Q. Per Saudi Aramco standard, what is the minimum size of grounding grid conductor [cable]?
70 mm2

Q. Per NEC, what would be the size of equipment grounding copper conductor for equipment protected by over current device rated 600 amperes?

NEC‐ article : 250 Table‐122. 1 AWG copper(35‐50mm sq) or 2/0 AWG copper –clad (70mm sq.)

Q. Per NEC, what would be the size of grounding electrode copper conductor for alternating current system having largest service conductor sized 350 kcmil?

1600 AMP. Copper conductor 4/0 AWG 120mm2

Q. How the grounding conductor would be connected to underground grounding grid?

a) By thermite welding or brazing.

b) By approved grounding compression connectors.

Q. What do the following letters denote on electrical equipment and explain the markings?

Exd –Explosion Proof Glands or Flame Proof
11B – Combustible dust Acetaldehyde, Ethylene
T1 ‐ 450°C Temp.

T2 ‐ 300°C Temp.

T3 ‐ 200°C Temp.

T4 ‐ 135°C Temp.

T5 ‐ 100°C Temp.

T6 ‐ 85°C Temp.

Q. On electrical equipment being used in hazardous area you may see the letter UL or C.S.A, what do these abbreviations stand for?

UL – Under Writer Laboratories
C.S.A –Canadian Standard Association

Q. A 3 phase system has phase to phase 480V AC , what is the phase to earth/neutral voltage? Show calculation.

480/√3 =277V Line current = √3 phase voltage (√3 = 1.732)

Q. Per NEC, what are the instances where seals fittings are needed?

When a conduct run is crossing hazardous boundaries below ground requires boundary seal, side, electrical equipment, junction box & conduit. Any breaking, sparking & heat producing device must be required fittings.

Q. How to minimize the effect of breathing in conduit installation?

Low point drain and breather shall be provided.

Q. Name type of cables suitable for class 1, division 1 and division 2 locations?

Class1, division 1 ,and division 2 locations suitable cable is XLPE , Polyethylene , EPR , Armored
cable

Q. How many degrees bend permitted in a conduit run?

360° between pull box to pull box.

Q. Per NEC, what is the minimum number of conduit threads should be engaged at hazardous locations?

Five (5) Full Threads should be engaged.

Q. What is the color code of grounding neutral and phase conductor?

Grounding ‐ Green
Neutral – White
Phase – Black

Q. What is minimum temperature rating for low voltage?

90° C Dry & 75°C Wet

Q. Name the type of tests required for testing following cables:

• Medium voltage power cables – Megger test & DC High Potential test
• Catholic protection – Holiday test
• Low voltage cables – Megger test & continuity test.

Q. Name some of the tests required for testing following equipment:

1. Oil type transformers – Winding test and Ratio test
2. Electrical Motors – Winding test, Resistance test, Megger test
3. Batteries – specific gravity, voltage, current
4. Circuit Breakers – Megger & Ductor test, primary current Trajection test

Q. What is the NEMA rating for electrical enclosures installed in the following environments:
1. Indoor – NEMA – article – 250
2. Outdoor – 3R , 3CR4
3. Corrosive environment – 4X

Q. Per NEC , what is the minimum working clearance in front of low voltage electrical equipment?

Minimum 3 Feet (900mm)

Q. Per S. Aramco standard , what is the ambient temperature rating for electrical equipment?

40°C

Q. How many divisions and groups class Ι atmospheric hazards are divided into? And what are the locations covered by each division?

Class Ι ‐ zone 0 – flammable gasses or vapor are present in air
classΙ ‐ zone Ι ‐flammable gasses or vapor are likely to exist under normal operation condition

Q. Define following for enclosures containing arching electrical device and installed in hazardous area?

1. Type – NEMA type 4x
2. Safety factor – Exia
3. Flame tight – Exid

Q. What type of equipment is this statement describing? The energy released from this type of equipment is insufficient to cause ignition.

Class Ι zone Ι location

Q. What are the most important things to check on lighting fixture installed in a hazardous location?And where these need to be shown?

To be check and confirm fixture are explosion proof it should shown in fitting name flute itself.

Q. Per Aramco standard, what are the acceptable types of underground conduits?

Threaded rigid steel hot dip galvanized and pre coated.

Q. What is IEEE standard work clearance around high voltage transformers?

Minimum – 10 feet – 3mtrs. as per NEC table – 110.31

Q. Per Aramco standards, what is the maximum resistance value per mined for a grounding system at industrial area?

1 OHM

Q. How many threads of rigid steel conduit must be engaged in a hazardous area?

5 threads. As per NEC – 501.4 (A) (1)

Q. How do you determine the correct size equipment ground conductor for a 1600 amp. Over current device?

As per NEC – article . Table – 250 – 122 ‐ Ground Conductor for – 4/0 AWG – 120 mm2

Q. What size junction is required if you have a 4” conduit straight in and straight out? What size for angle pulls?

As per NEC – 314.28
For straight in and straight out: less than 8 times ‐ 8×4=32”inch
For angle pulls : less than 6 times ‐ 6×4=24”inch

Q. What is the maximum percent of cross section a conduit can be filled containing 3 or more conductors?

40% as per NEC chapter – 9 table – 1

Q. What are the requirements for conductor insulation at light fixture terminations?

Insulation minimum thickness 0.25mm that have insulated suitable temperature not less than 125°C.

Q. What is the maximum number of overcurrent devices allowed in a panel board?

As per NEC – 408.15 42 number.

Q. What is a “T” number as it relates to equipment in a Hazardous Area?

Temperature class. As per NEC table – 500.8(B)

Q. Can you use light fixtures as a raceway?

No

Q. Where are conduit supports required for rigid steel?

Horizontal : 3 mtrs vertical : 6 mtrs . As per NEC – 344.30

Q. Where are seal fitting required?

Instrument side and enclosure side in hazardous area.