Interview Questions and Answers

Q:-What test specimens are required?

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A. side bends tests
B. 1 face bend and 1 root bend
C. 1 T-joint break
D. 2 side bends and 2 root bends
E. None of the above

Top 10 Interview Questions Related To Pipes Supports

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Interview Questions Related To pipes Supports:-

1. What are the Criteria for Pipe Supporting?

Answer: –

Following are the points, which should be taken into account for proper supporting: –

A. Load of bare pipe + fluid + insulation (if any).
B. Load of bare pipe + water fill.
C. Load of valves and online equipment and instrument.
D. Thermal loads during operation.
E. Steam out condition, if applicable.
F. Wind loads for piping at higher elevation, if required.
G. Forced vibration due to pulsating flow.
H. Bare pipe with size above 12” shall be supported with Pad or Shoe.

2. What is the basic span of supports for 2”/6”/10”/24” pipe?

Answer: –

Basic Span is 5.5m / 9m / 11.5m / 15m respectively.

3. What is the function of providing the anchor, cross guide and guide for piping?

Answer: –

Anchor is provided to restrict all the axial and rotational movements of pipe, whereas cross guide is
provided to restrict displacements of pipe along with the axis perpendicular to its centerline and Guide is provided to restrict the longitudinal movements of pipes along with its axis.

4. How is piping to Tank inlet nozzle is supported and why?

Answer: –

Piping to Tank Nozzle is supported with spring type support (first support from Nozzle) in order to
make the nozzle safe from the loads which occurs due to the displacement of pipe ( Displacement
may be due to thermal expansion of pipe, tank material, tank settlement etc).

5. What are the types of flexible spring hangers?

Answer: –

1. Constant Spring Hanger 2. Variable Spring Hanger.

6. What is the purpose of providing Graphite Pads in supports below shoes?

Answer: –

To reduce the friction factor. The coefficient of friction for Graphite Pads is 0.1

7. Where do you provide Anchor and Slotted Support of Heat Exchanger?

Answer: –

Anchor support of Heat exchanger is provided on the side from which Tube bundle will be pulled out for the purpose of maintenance work also it is based on the growth of the connecting piping as
exchanger should grow with the piping.

8. What should be the material of shoes for supporting AS pipes & why?

Answer: –

If CS shoes are used then pad in contact with the pipe shall be of Alloy steel to avoid dissimilar
welding at pipe. To avoid alloy steel welding and dissimilar welding, fabricated clamps either of CS or SS can be used.

9. What are sway braces?

Answer: –

Sway braces are essentially a double acting spring housed in a canister. Their purpose is to limit the
undesirable movement. Undesirable movement means movement caused by wind loading, rapid
valve closure, relief valve opening, two phase flow or earthquake.

10. What is the difference between variable spring hanger and constant spring hanger?

Answer: –

Variable spring Hanger: –
As the name itself indicates the resistance of the coil to a load changes during compression.
Constant spring Hanger: –
Constant spring hanger provides constant support force for pipes and equipment subjected to vertical movement due to thermal expansion.


Q:- Under most circumstances, which of the following do you consider to be duties of a welding inspector?

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1. The supervision of welders  

2. Procedure writing  

3. Qualifying welders  

4. All of the Above

Q:- For welder qualification, the specimens shall be prepared for tensile-strength, nick-break, and bend tests. When tensile-strength tests are omitted:

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1. The welder is not qualified
2. The weld must be redone
3. The is not covered in API 1104
4. Tensile-Strength specimens shall be subject to the nick-break test
5. Extra face bends must be tested

Interview Questions Answers Related To Valves: –

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Questions related to valves: –

  1. What is the function of valves?

Answer: –

  1. Isolation.
  2. Regulation.
  3. Non-Return.
  4. Special purpose.
  1. How the valves are classified based on their function?


A. Isolation.

  1. Gate valve.
  2. Ball valve
  3. Plug valve.
  4. Piston valve.
  5. Diaphragm Valve.
  6. Butterfly valve.
  7. Pinch valve.

B. Regulation

  1. Globe valve.
  2. Needle valve.
  3. Butterfly valve.
  4. Diaphragm valve.
  5. Piston valve.
  6. Pinch valve.

C. Non- Return

  1. Check valve.

D. Special purpose

  1. Multi- Port valve.
  2. Flush Bottom valve.
  3. Float valve.
  4. Foot valve.
  5. Line blind valve.
  6. Knife Gate valve.


  1. How the valves are classified based on its method of operation?

Answer: –

Valves are classified based on its method of operation as: –

  1. Self- operated valves.
  2. Operated valves.


  1. Name the Self – operated & operated valves?


Mainly the check valves are self-operated and all other valve types comes under operated valves.


  1. How the valves are classified based on end connection?

Answer: –

Valves are classified based on end connection as: –

  1. Screwed ends.
  2. Socket ends.
  3. Flanged ends.
  4. Butt weld ends.
  5. Wafer type ends.
  6. Buttress ends.

End connection means arrangement of attachment of the valve with the equipment or the piping.


  1. What are the types of check valves?

Answer: –

Check valves are divided into two types based on check mechanism as: –

  1. Lift check valve.
  2. Swing check valve.


  1. What do you mean by special purpose valves?


Valves that perform duties other than the two-way isolation, control and check are called special Purpose valves.


  1. What are Glandless piston valves? Where these are used?


Glandless piston valves are regulating valves used in steam services.

Questions related to Pipe Fittings: –

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1. How can flanges be classified based on Pipe Attachment?

 Answer: –

Flanges can be classified based on pipe attachment as: –

Slip – on. : – The Slip-on type flanges are attached by welding inside as well as outside. These flanges are of forged construction.

Socket Weld. : – The Socket Weld flanges are welded on one side only. These are used for small bore lines only.

Screwed. : – The Screwed-on flanges are used on pipelines where welding cannot be carried out.

Lap Joint. : – The Lap Joint flanges are used with stub ends. The stub ends are welded with pipes & flanges are kept loose over the same.

Welding Neck. : – The Welding neck flanges are attached by butt welding to the pipe. These are used mainly for critical services where the weld joints need radiographic inspection.

Blind. : – The Blind flanges are used to close the ends which need to be reopened.

Reducing. : – The reducing flanges are used to connect between larger and smaller sizes without using a reducer. In case of reducing flanges, the thickness of flange should be that of the higher diameter.

Integral. : – Integral flanges are those, which are cast along with the piping

component or equipment.

  1. How can flanges be classified based on Pressure- temperature ratings?

Answer: –

Flanges are classified based on pressure temperature ratings as: –

#A. 150

#B. 300

#C. 400

#D. 600

#E. 900

#F. 1500

#G. 2500

Pressure temperature rating carts in the standard ASME16.5 specify the non-shock working

gauge pressure to which the flange can be subjected to at a particular temperature.

  1. How can flanges be classified based on facing?

Answer: –

Flanges are classified based on facing as: –

  1. Flat face. (FF)
  2. Raised face. (R/F)
  3. Tongue and groove. (T/G)
  4. Male and female. (M/F)
  5. Ring type joint. (RTJ)
  1. How can flanges be classified based on face finish?

Answer: –

Flanges are classified based on face finish as: –

  1. Smooth finish.
  2. Serrated finish.
  1. Where the smooth finish flange & serrated finish flange finds its use?

Answer: –

The smooth finish flange is provided when metallic gasket is provided and serrated finish flange is provided when non-metallic gasket is provided.

  1. What are the types of serrated finish provided on flange face?

Answer: –

  1. Concentric or
  2. Spiral (Phonographic)


  1. How the serration on flanges is specified?


The serration on flanges is specified by the number, which is the Arithmetic Average Rough

Height (AARH).

  1. Where the concentric serration is insisted for face finish?

Answer: –

Concentric serration are insisted for face finish where the fluid being carried has very low

density and can find leakage path through cavity.

  1. How the Gaskets are classified based on the type of construction?

Answer: –

Based on the type of construction, gaskets are classified as: –

  1. Full face.
  2. Spiral wound metallic.
  3. Ring type.
  4. Metal jacketed.
  5. Inside bolt circle.

  1. What is the most commonly used material for Gasket?

Answer: –

Compressed Asbestos Fibre.

  1. Which type of gasket is recommended for high temperature & high-pressure application?

Answer: –

Spiral Wound Metallic Gasket.

  1. What are the criteria for selection of MOC of Spiral Wound metallic Gasket winding material?

Answer: –

The selection of material of construction for Gasket winding depends upon: –

  1. The corrosive nature and concentration of fluid being carried.
  2. The operating temperature of the fluid.
  3. The relative cost of alternate winding material.


  1. What are the most common materials used for spiral wound metallic gasket winding?

Answer: –

The most commonly used material for spiral wound metallic gasket winding is: –

  1. Austenitic stainless steel 304 with asbestos filler.
  2. Austenitic stainless steel 316 with asbestos filler.
  3. Austenitic stainless steel 321 with asbestos filler.

  1. Which material is used as filler material for spiral wound gasket in case of high temperature services?

Answer: –

For very high temperature services, graphite filler is used.

  1. What is centering ring in connection to spiral wound gasket?

Answer: –

Spiral wound gaskets are provided with carbon steel external ring called centering ring.

  1. What will be the AARH finish on flange face for using spiral wound gasket?

Answer: –

125-250 AARH finish.


  1. On which type of flanges the use of spiral wound gasket are restricted?

Answer: –

rating spiral wound gasket on flanges other#ASME B16.5 does not recommend the use of 150 than welding neck and lapped joint type.

  1. Up to what temperature limits the low strength carbon steel bolts should not be used for flanged joints?

Answer: –

C.°C or below – 28°Flanged joints using low strength carbon steel shall not be used above 200

  1. How the pipe fittings are classified based on end connections?

Answer: –

Pipe fittings are classified based on end connection as: –

  1. Socket weld fittings.
  2. Screwed end fittings.
  3. Beveled end or Butt weld fittings.
  4. Spigot socket fittings.
  5. Buttress end fittings.

  1. Up to what temperature the carbon steel materials shall be used?

Answer: –

Carbon steel materials shall be used for temperature up to 425C°


  1. Which material is used for temperature above 426C°?

Answer: –

Alloy steel materials shall be used for temperature above 426 C°

  1. Which type of material is used for corrosive fluid?

Answer: –

Stainless steel materials shall be used for corrosive fluid.

  1. Which type of piping materials are used for drinking water, instrument air etc?

Answer: –

Galvanized steel materials shall be used for drinking water, instrument air and NI lines (LP).

  1. What is the difference between Pipe and Tube?

Answer: –

Pipe is identified by NB and thickness is defined by Schedule whereas Tube is identified by OD & its thickness as BWG (Brimingham wire gauge or 1/100 inch).

  1. From which size onwards NB of pipe is equal to OD of Pipe?

Answer: –

From the size 14” and onwards NB = OD of pipe.

  1. What should be the radius of long radius elbow?


1.5D (Where “D” is the diameter of the pipe.)

  1. What should be the radius of short radius elbow?


1D(Where “D” is the diameter of the pipe.)

  1. What is the basis of using of short radius & long radius elbow?


Long radius elbow are used for small pressure drop whereas short radius elbow are used for high pressure drops. For catalyst flows vary long radius elbows are used.

  1. Normally where do we use the following?

    (1) Eccentric reducers.   (2) Concentric reducers.


  1. Eccentric reducers = Pump suction to avoid Cavitation, To maintain elevation (BOP) in rack.
  2. Concentric reducers = Pump discharge, vertical pipeline etc.

  1. Concentric reducer is used in pump suction. (Yes / No). Explain.


No. Air pockets may form if concentric reducer is used at pump suction, which results in cavitation

and cause damage to Pump. To avoid this problem, Eccentric Reducer with flat side up (FSU) is

used in Pump Suction.

  1. Where the ERW spiral & longitudinal pipes are used?


Use depends upon the availability of pipes. Nothing functional difference.


  1. Where the ERW & Seamless pipes are used?


Above 18” ERW pipes are used. Below 18” seamless pipes are used. Seamless pipes can sustain

higher temperature & pressure.


  1. What is the main use of ASTM A53 & A106 Gr.B pipes?


ASTM A53 pipes are mainly used for utility services whereas A106 Gr. B pipes are used for high

Pressure & high temperature services.

  1. From which side of pipe will you take a branch connection?


When fluid is Gas, Air or Steam and Cryogenic Service – Topside.

When Fluid is Liquid – Bottom Side.

  1. Why don’t we take a branch for Cryogenic Service from bottom side though the fluid is in liquid state?

Answer: –

There is the chance of ice formation during normal operation and since ice flows from the bottom of the pipe it will block the branch pipe connection.

  1. Why do we provide High Point Vent (HPV) and Low Point Drain (LPD) in piping?


HPV – For removing Air during Hydro-test.

LPD – For draining water after conducting Hydro-test.

  1. What do you mean by Jacketed Piping?

Answer: –

Piping which is recognized as providing the most uniform application of heat to the process, as well

as maintaining the most uniform processing temperatures where steam tracing is not capable of

maintaining the temperature of fluid constant. Usually used for molten sulphur, Polymers service.

  1. What is the minimum distance to be maintained between two welds in a pipe?

Answer: –

The thumb rule is that the minimum distance between adjacent butt welds is 1D. If not, it is never

closer than 1-1/2″. This is supposedly to prevent the overlap of HAZs. Minimum spacing of

circumferential welds between centerlines shall not be less than 4 times the pipe wall thickness or

25 mm whichever is greater.

  1. What do you mean by IBR and which lines comes under IBR purview?

Answer: –

IBR: Indian Boiler Regulation Act.

Steam lines with conditions listed bellow comes under IBR purview : –

  • Lines for which design pressure is 3.5 kg/sq. cm and above.
  • Line size above 10” having design pressure 1.0 kg/sq. cm and above.
  • Boiler feed water lines to steam generator, condensate lines to steam generator and flash drum.

  1. What are Weldolet and Sockolet? And where they are used?


Weldolet and Sockolet are basically self-reinforced fittings.

Weldolet is used for Butt weld branch connection where standard tee is not available due to size

restrictions and the piping is of critical / high-pressure service. Sockolet is used for socket welding

branch connection, which require reinforcing pad.

  1. What is the MOC for Superheated high pressure Steam Lines?


A 335 Gr. P I / P 11, Composition: Cr. – ½ Mo (P1) / 1¼ Cr. – ½ Mo (P11)

  1. What is the normal upstream and downstream straight length of orifice flow meter?

Answer: –

Upstream – 15D Downstream – 5D

Piping Interview Questions related to Materials: –

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Questions related to Materials: –

1. Q:-What is the ASTM code for the following?

  1. Pipes :-
  2. Carbon Steel II. Alloy Steel III. Stainless Steel IV. Nickel Steel.
  3. Tubes: –
  4. Carbon Steel II. Alloy Steel III. Stainless Steel IV. Nickel Steel.
  5. Wrought Iron Fittings: –
  6. Carbon Steel II. Alloy Steel III. Stainless Steel IV. Nickel Steel.
  7. Forged Fittings: –
  8. Carbon Steel II. Alloy Steel III. Stainless Steel IV. Nickel Steel.
  9. Cast Fittings: –
  10. Carbon Steel II. Alloy Steel III. Stainless Steel IV. Nickel Steel.
  11. Plates: –
  12. Carbon Steel II. Alloy Steel III. Stainless Steel IV. Nickel Steel.


Answer: –

  1. Pipes:-
  2. Carbon Steel : – ASTM A53 Gr. A/B, ASTM A106 Gr. A/B/C, ASTM A333 Gr.1/Gr.6
  3. Alloy Steel :- ASTM A335 Gr.P1/P2/P5/P7/P9/P11/P12/P22.

III. Stainless Steel :- ASTM A312TP304/TP304L/TP304H/TP308/TP310/TP316/TP316L/


  1. Nickel Steel :- ASTM A333Gr.3/ Gr.8.


  1. Tubes:-
  2. Carbon Steel :- ASTM A178/179/192, ASTM A334 Gr.1/6.
  3. Alloy Steel :- ASTM A161T1, ASTM A213T1/T2/T5/T7/T9/T11/T12/T22.

III. Stainless Steel :- ASTM A213 TP304/TP304L/TP304H/TP310/TP316/TP316L/TP316H/


ASTM A608 HK40.

  1. Nickel Steel :- ASTM A334Gr.3/Gr.8
  2. Wrought Iron fittings :-
  3. Carbon Steel :- ASTM A234Gr.WPA/B, ASTM A420 Gr.WPL6.
  4. Alloy Steel :- ASTM A234 WP1/WP5/WP7/WP9/WP11/WP12/WP22.

III. Stainless Steel :- ASTM A403 WP304/WP304L/WP304H/WP309/WP310/WP316/

WP316L/WP316H/ WP317/WP321/WP321H/WP347/WP347H/


  1. Nickel Steel :- ASTM A420WPL6/WPL8.
  2. Forged Fittings : –
  3. Carbon Steel :- ASTM A181. ASTM A105, ASTM A350 LF1/2.
  4. Alloy Steel :- ASTM A182F1/F2/F5/F7/F9/F11/F12/F22.

III. Stainless Steel :- ASTM A182F6/F304/F304L/F304H/F310/F316/F316L/F316H/F321/


  1. Nickel Steel :- ASTM A350 LF3, ASTM A522.
  2. Cast Fittings: –
  3. Carbon Steel :- ASTM A216, ASTM A352 LCB/C.
  4. Alloy Steel :- ASTM A217 WC1/WC6/WC9/C5/C12.

III. Stainless Steel :- ASTM A217 CA15, ASTM A296 CA15, ASTM A351 CF8/CF3/CH20/

CK20/CF 8M/CF 3M/CF 8C/HK40.

  1. Nickel Steel :- ASTM A352LC3.
  2. Plates: –
  3. Carbon Steel :- ASTM A285, ASTM A515, ASTM A516.
  4. Alloy Steel :- ASTM A387 Gr.2/Gr.5/Gr.7/Gr.9/Gr.11/Gr.12/Gr.22.

III. Stainless Steel :- ASTM A240 TP410/TP405/TP430/TP304/TP304L/TP309/TP310S/


  1. Nickel Steel :- ASTM A203 Gr.D/Gr.E, ASTM A353.


2. Q:-What is the basic difference between Pipe specification A106 Gr.A / Gr.B/ Gr.C.?

Answer: –

Difference is due to the Carbon content.

% of carbon content in : –

  1. ASTM A106 Gr. A – 0.25 %
  2. ASTM A106 Gr. B – 0.30 %

II ASTM A106 Gr. C – 0.35 %.

3. Q:-What is the difference between pipe specification ASTM A312 TP 304 & ASTM A312 TP304L, ASTM A312 TP 316 & ASTM A312 TP 316L?


Answer: –


Difference is due to the Carbon content. The Letter “L” denotes lower percentage of carbon.

% of carbon content in : –

  1. ASTM A312 TP 304 – 0.08 %
  2. ASTM A312 TP 304L- 0.035%

III. ASTM A312 TP 316 – 0.08 %

  1. ASTM A312 TP 316L- 0.035%




Interview Questions and Answers | Welding Interview Questions

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Interview Questions and Answers

Q:- What is the standard for Process (or) Plant piping systems?
Answer: ASME B 31.3

Q:- What is the standard for Power Piping systems?
Answer: ASME B 31.1

Q:- What is the standard for liquid Petroleum Transportation piping systems?
Answer: ASME B31.4

Q:- What is the standard for Gas Transmission and Distribution piping systems?
Answer: ASME B31.8

Q:- What is the Code for Welding of Pipelines and Related facilities?
Answer: API 1104

Q:- What is the standard for welding rods Electrodes and filler metals?
Answer: ASME Sec-IIC

Q:- What is the standard for Non-destructive Examination?
Answer: ASME Sec-V

Q:- What is the standard for welding and Brazing Qualifications?
Answer: ASME Sec-IX

Q:- Which type of process we are using in field/fabrication shop?
Answer: Fusion welding

Q:- What is the specification/classification for carbon steel filler wire?
Answer: AWS 5.18/ER70-Sx

Q:- What is the specification/classification for carbon steel Electrode?
Answer: AWS 5.1/E-XXXX

Q:- Where we can use E-6010 type electrode?
Answer: we can use at root pass for deep penetration

Q:- What is the meaning for ASME?
Answer: American Society for Mechanical Engineering

Q:- Which type of electrode we are using in GTAW process?
Answer: Non-Consumable Tungston Electrode

Q:- How Many times we can dry the electrodes?
Answer: Only one time

Q:- Why we are baking the electrodes?
Answer: To remove the moisture content from the Electrodes.

Q:- What is the standard for Structural steel fabrication?
Answer: AWS D1.1

Q:- What is the standard for Welding symbols?
Answer: AWS A2.4.

Q:- What is the hydrotest pressure?
Answer: 1.5 Times of design pressure.

Q:- What is the drying temperature for Stainless Steel electrodes?
Answer: 120 to 250 degree temperature.

Q:- What is the drying procedure procedure for Low hydrogen electrodes?
Answer: 260 to 430 degree temperature.baking for two hours

Q:- What are the defects we can find in visual Inspection?
Answer: Porosity,Undercut,Surface crack (HIC),Side wall fusion on fusion boundary.

Q:- What is the Procedure for Fit-Up inspection?
Answer: Base metal classification,cleaning,Alignment,root gap,root face,bevel angle & mismatch (or) overlap.

Q:- What is the internal overlap (or) mismatch for piping?
Answer: 1.5 mm.

Q:- How much root face are allowed?
Answer: As per WPS (or) 0.8 to 1.6 mm

Q:- What is meaning for F – Number?
Answer: F- is filler metal grouping Number.

Q:- What is meaning for P – Number?
Answer: P – is base metal grouping Number.

Q:- What is meaning for A – Number?
Answer: A – is electrode chemical analysis number.

Q:- How much bead width we can allow?
Answer: Max 3 times of electrode diameter.

Q:- How much area is required for Pre-heat?
Answer: 75 mm minimum from both end of the Joint.

Q:- Which section we are using for NDT?
Answer: ASME Sec-V

Q:- What are the essential variables for SMAW process?
Answer: In base metal thickness, P-number, dia of pipe, pre, post weld heat treatment
In filler metals F,A-numbers, dia

Q:- What are the essential variables for GTAW process?
Answer: In Base Metal thickness, P-number, dia of pipe, pre, post weld heat treatment… In Filler Metals F, A-numbers,dia of filler metal

Q:- If welder made test by 2’’ dia, what is his range qualified?
Answer: He has qualified 1’’-dia and above.

Q:- If welder made test by 14 mm thickness, what is his thickness range qualified?
Answer: He has qualified unlimited thickness.

Q:- What is carbon % in low carbon steel?
Answer: Max 0.30 %

Q:- What is the interpass temperature for carbon steel materials?
Answer: Max 315’C

Q:- What is meaning for SAES,SAEP and SAMSS?
Answer: Saudi Aramco Engineering Standards
Saudi Aramco Engineering Procedures
Saudi Aramco Materials System Specification.

Q:- How much under cut depth allowed in piping?
Answer: 0.8 mm

Q:- How much area is required for Pre-heat?
Answer: 75 mm minimum from both end of the Joint.

Q:- How much percentage is allowed more than test pressure in Pressure relief device?
Answer: Test pressure plus10% (10% should be lesser than 50Psi).

Q:- How much gap is allowed in socket weld?
Answer: 1.5 mm minimum before welding.

Q:- What is the minimum fillet size in socket weld?
Answer: Minimum 3 mm fillet size.

Q:- Hydro test.
1. Piping Internal Cleaning
a. Air compressor
b. Air blower
c. Electrical cable
d. Generator
c. Wire brush
d. cotton waste cloth
e. water tanker water with pump
2. Testing
a. Pressure gauge-(30days calibration valid, range 1.5 to 2 times test pressure)
b. Test manifold (calibration validity)
c. Pressure relief valve( Set to 5% above test pressure)
d. Test pump
e. Water tank
f. Hoses
g. Test blind
h. Test water (refer as per project specification)
II. Test package
1. Calibration Certificates of Gauges ,relief valves
2. P&ID and ISO Drawing
3. Test Package Control sheet
4. Marked up P&ID
5. As built Drawing
6. Welding log
7. NDE report
8 .Punch list –all punch list cleared (category one)
9. Pressure test Check sheet
10. Safety check lists

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