WELDING QUESTION AND ANSWER FOR WELDING FOREMAN/ SUPERVISORS

WELDING QUESTION AND ANSWER FOR WELDING FOREMAN/ SUPERVISORS

Q.1.     What is Welding ?

Ans.     Welding is process to joining Two Similar or dissimilar materials after heating with pressure or    

            without pressure.

Q.2.     What is difference between Pipe and Tube?

Ans.     Pipe is a tubular shape material which is used for transportation of fluid and Tube is used to transfer the Heat, Pipe is measured by NPS (dia) with schedule (Thk.)Where Tube is measured by OD.

Q.3      What are the Process of Welding.

Ans.     The following are the main welding process generally used for construction work.

            1.         SMAW            -  Shielded Metal Arc Welding.Also called Stick welding.

            2.         GTAW                        -  Gas Tungsten Arc Welding. also called Tig welding.

            3.         GMAW           -  Gas metal arc welding, also called CO2 Welding

            4.         FCAW            -  Flux Cored Arc Welding

            5          SAW               -  Submerged Arc Welding.

Q.4      What is WPS , PQR & WPQR?

Ans.     WPS    -           Welding Procedure Specification (A procedure before to start the welding)

PQR    -           Procedure qualification Record ( All variable record noted during qualification during                        

welding process)

           WPQR -           Welder Procedure qualification Record.( Variable recording during welders   

                                    qualification)

Q.5      What is difference between ELECTRODE and FILLER WIRE?

Ans.     Current passes through Electrodes and fused where as in filler wire Current Passes through Tungsten

            electrode and fused externally.

            Electrode is coated with flux which is prevent oxidation.

            Filler wire is barred and Inert gas used to prevent oxidation.

Q.6      Explain about the following codes.

            ASME, AWS, ASTM, ANSI, BS, ASNT, API,

Ans.     ASME -           American Society of Mechanical Engineer

            AWS   -           American Welding Society

            ASTM -           American Society Of Testing Materials

            ANSI  -           American national standard institute

            B.S     -            British Standard        

            ASNT -           American society of Non destructive Testing

            API     -           American Petroleum institute.

Q.7      Abbreviation of the following codes.

            ASME SEC II,V,VIII, IX

            API 1104                 

            D1.1

            B31.1, B31.3

Ans.     ASME SEC II -           Code of materials

            ASME SEC V -           Code of NDT

            ASME SEC VIII-       Code for construction of pressure Vessel

            ASME SEC IX-          Code of Welder Qualification/WPS/BAZING

            API-                            Cross Country Pipeline

            B31.1-                         Code of Power piping

            B31.3-                         Code of process Piping

            AWS D1.1                  Structural Welding

Q.8.  What is DCEN and DCEP?

Ans.   DCEN- Direct Current Electrode Negative – Straight Polarity- GTAW- More Heating of W/P

          DCEP -  Direct Current Electrode positive   _ Reverse Polarity- SMAW-More heating of Electrodes

          

Q.9. What is difference between TANK, BOILER and Vessel?

Ans. Tank is used for Storage where Vessel is used for Process and boiler is used for Steam generation.

Q.9  Explain Up-hill and Down-hill Progression?

Ans.     UP-Hill Progression - Welding in upward direction ↑

            Down-Hill                -  Welding in downward direction ↓

Q.10.  What is the number of protected Welding glass-Shade

Ans.     10,12,14

Q.11. MSDS?

Ans.  Material Safety data sheet.

Q.12 What is the purpose of Flux?

Ans.  Shielding, De oxidation , Ionizing, Alloying, Insulating .

Q.13. How will you identify L.H Electrode. (Low hydrogen electrode)

Ans.  Whose last number is 5,6,8 Example: EXXX5, EXXX6, EXXX8 (E7018)

Q.14, Explain about E7018 Electrode.

Ans.  This electrode is a Low hydrogen and having a good properties in all aspect and is used for dynamic

          loaded structural, Piping and equipment.This is used by the process SMAW

            E          -           Electrode

            70        -           Minimum Tensile Strength in Psi -    70000 psi

            1          -           Capabilities to weld in all position

            8          -           Electrical Characteristic / Flux coating

Q.15. Explain about ER70S-2 Filler wire.

Ans.  Filler wire is used for tig welding and this specification is for CS. Welding process for this is GTAW

            ER       -           Electrode Rod

            70        -           Tensile Stength in PSI- 70000 PSI

            S          -           Solid wire

            2          -           Chemical Composition.

Q.16. Explain about ER71T-1 Filler wire.

Ans.  Filler wire is used in rolled with fast production in fab.shop or site involved welding process FCAW welding and this specification is for CS.

            ER       -           Electrode Rod

            7          -           Tensile Stength in PSI- 71000 PSI

            T          -           Tubular filler wire

            1          -           Chemical Composition.

FCAW Process is self shielding because of flux inside of the tubular wire. It may or may not required any inert gas.

Q.17. What is P, A, and F Number?

Ans.     P-         Identification of Parent metal number

            A         Identification of Chemical composition of filler wire

            F          Identification of Filler metal number

Q.18. What type of gases is utilized for Shielding/ Purging?

Ans.     Argon, CO2, Nitrogen etc

            GTAW PROCESS  -  ARGON 15-25 PSI

            GMAW PROCESS-   CO2

Q.19. What is Pre-heating and PWHT?

Ans.     Preheating is done before welding to control cracking and porosity, min-150F above 19mm thk mtrl.

            If temp. observed below hand temp. 

            PWHT-POST WELD HEAT TREATMENT-

            PWHT is done after complete the welding (24-48 HRS) to release the stress induced during welding.

Q.20. How L.H Electrodes handle?

Ans. 

Baking @260-350 °C for 1-2 hrs.

                        ↓

Holding @120-149°C For 24 hrs.

                        ↓

Issue to Quivers @65-120 °C For 4-8 hrs.

                        ↓

Unused Electrodes For Rebaking.

Q.21. Important Documents file to be maintained for Electrode Handling System.

Ans.      Requisition form –Issuing filler metal

             Baking Record Book

             Holding Record Book

             Filler metal consumption record

             Mill test certificate record

             Calibration certificate of Oven.

Note:  All filler metal to be stock in dry, clean and humidity free area. Different Specification of Filler metal to be kept separate in rack and proper identification to be mark.SS and CS not to be kept in same place to prevent corrosion.

Q.22.   What is essential variable and Non essential variable in WPS?

Ans.     Variable that effect Chemical or Mechanical Properties of materials. Exp. Joint Design, Process, P or

F No changed, progression, Electrical characteristic etc.

Non-Variable that not effect Chemical or Mechanical Properties.Exp. Bevel angle, Diameter change,

Current fluctuation etc.

Q.23.   According to what codes welder qualification are carried out.

Ans.     ASME SEC IX – For process and power piping.

            API 1104           _ For Cross country pipeline

            AWSD1.1         _ For Structural

Q.24. What types of pipe is generally used in plant?

 Ans.  Manufactured wise

          Seamless Pipe, ERW Pipe (Seam pipe), Plastic pipe (GRE,FRB Etc)

          Materials wise

          Carbon steel (CS), Stainless steel (SS), Low temperature carbon Steel (LTCS), Duplex stainless steel     

          (DSS).

Q.25. What is Duplex Stainless steel (DSS)

Ans.   Combination of Austenite and Ferrite, Good mechanical Properties, Corrosion resistant, and

          capability to work in negative temp. Generally this pipe is used in Gas plant. This is magnetically

          attraction.

Q.26.  In welding where purging is required ?

Ans.   At the time of SS or DSS welding purging is required to prevent oxidation.

Q.27. How pipe joint is purged?.Up to what thickness purging is provided. What type of gas is    

          utilized.

Ans.  Argon gas is used for purging upto 6mm (Root+HP). We blocked about 100 mm away from the welding joint (inside pipe) by Paper Dam, Rubber Dam, Air balloon etc and passed the Argon gas through purging pipe connected with cylinder whose flow controlled according to the requirement. When Oxygen removed from the pipe joint area then welding started.

Q.28. How will you check the oxygen %age?

Ans.  Oxygen percentage is checked by Oxygen analyzer/ Oxygen purge monitor.

          FOR  SS            -           0.2 %  Oxy. max.

          FOR DSS          -           0.05 % Oxy.max. 

Q.29. Which types of fitting is utilized in piping?

Ans.  Elbow, Flange, Tee, Socket, Blind, Nipple, Valve, Nut Bolt, Gasket, Expansion below etc.

Q.30. Explain Types of Valve.

Ans.      Isolation Valve- To stopped the fluid flow. Example Gate Valve.

            Regulation Valve-To regulate the valve as per required flow- Example Glob Valve.

            Non Return Valve- To flow the fluid in one direction only- Exp. Check Valve

            Special Purpose Valve- This valve is used as per special requirement as below

To release high pressure – Exp. Safety valve,

To release air -           Air release Valve

Auto flow control-      Control valve

             

 Q.31. How you will select Filler Metal?

Ans. Filler metal selection is always on the base of Materials specification. Which is described some of the

         important selection of filler metal as below.

Parent Materials	P. No.	Filler Metal		Process	Material-Material
		Root	Fill up & Capping
ASTM-SA106 Gr.B ASTM-SA285 Gr.C ASTM-SA516 Gr.70	P1	ER70S-2	E7018	GTAW + SMAW	CS-CS
ASTM A312 TP304L F182 304L	P8	ER308L	E308L	GTAW + SMAW	SS-SS
ASTM A312 TP316L TP321,A182,F321,A358	P8	ER316L	E316L	GTAW + SMAW	SS-SS
ASTM A333 GR-6, A350,LF2,A420 WPL6	P1	ER80SNi-1 ER80SNi-2	E7018-1 E7081-C1	GTAW + SMAW	LTCS-LTCS
SA335 Gr.P11 SA213 Gr.P11	P4	ER80S-B2	E8018-B2	GTAW + SMAW	Alloy steel to Alloy steel
ASTM A335 Gr.P22 SA182 Gr.P22	P5A	ER90S-B3	E9018-B3	GTAW + SMAW	Alloy steel to Alloy steel
SA 335 GR.P91	P5B	ER90S-B9	E9015-B9	GTAW + SMAW	Alloy steel to Alloy steel
ASTM-SA106 Gr.B ASTM A312 TP304L	P8-P1	ER309 ERNiCr-3	E309 ENiCrFe3	GTAW + SMAW	CS-SS
BRAZING B88-Gr102		BCuP-2		OXY-ACETYLENE	CU

    DSS FILLER WIRE – ER2209 & ELECTRODE IS E22

    Electrode E6010 is used for root welding and suitable good for big bore, E6013 is also used for general  

    purpose work like light structure, water pipe etc.

Remarks,:  If the materials grade changed of the same specification then we select the higher one. exp.  

                      ASTM A312 TP304L& ASTM A312 TP316L to be welded then we use ER316L Filler wire.

                        Preheating is required in all Alloy joint where welding is to be carried out.@210 *C

                        PWHT is required after welding in alloy steel.

Q.32. What is the formulae to calculate of Electrodes quantity?

Ans.     W=      D X A X L

                        Efficiency                        Where,

W=      Weight of Electrode / wire in KG

D=       Density of Weld metal kg/m3

ρ =       density of steel = 7780 kg/m3 at 20 0C

A=       Cross sectional area of joint (m2)

L=       Length of joint

Efficiency,

SMAW=0.65,             GTAW=1.00,              GMAW=0.95,             SAW=1.00

Q.33. sketch & explain the following Pipe joints.

Parts of weld joints:-  Joint root, grove face, root face,  root edge, root gap, bevel , bevel angle, groove angle, grove radius etc.

Q.34. Explain defects of Welding, Cause and remedies.

Ans. 

DEFECTS	REASON/CAUSE	PREVENTION
Lack of fusion (Parent Material not fused in root or weld face)	Weld face more, Speed travel more, No root gap proper etc.	Joint should be as per WPS
Lack of Penetration (Incomplete root penetration)	Narrow root gap, Unskilled welder, Low current etc.	Proper skilled welders and current is required as per WPS.
Crack (Occur linear mark in welding or Heat effected zone)	Fast cooling process, improper tacking and supporting etc.	Proper heat treatment is required
Slag (When flux entrapped in molten metal during welding)	Not proper cleaning in between layers, Wet electrodes etc.	Need Proper cleaning.
Spatter (Excess materials spread on parent metal without fuse during welding)	High current, Barred electrode etc.	Proper current to maintain.
Arc Strike (When spark occur on pipe by electrodes/ holder )	Un skilled welders,	Need precaution, spark should not be on the pipe)
Porosity (A round spherical shape entrapped in molten metal)	Due to high current, wet electrodes, more wind pressure etc	To be minimize all these things.
Undercut (Cut appear in toe)	Due to high current.	To maintain current

           

Q.35.  What is Weld Affected Joint (HAZ)

Ans.    Parent materials whose atomic structural changed during welding is called HAZ. Up to. 2’’from weld toe.

Q.36.  What are the inspection Method of welding.

Ans.  Basically there are two method for examination of welding as below.

            NDT    -           Non destructive Test

            DT       -           Destructive Test.

Q.37.  Explain NDT & DT Methods.     

Ans.     Non destructive Test : This examination is done without destructive of materials, Following are the

            types of NDT.

·         VT-            Visual Test

·         RT -           Radiography Test. – Carried out by isotopes. (Gama ray)

·         UT-            Ultrasonic Test            _ By ultrasound wave m/c

·         MPT-         Magnetic Particle Test- By Magnet (Flux flaw)

·         DPT-         Dye Penetration Test-   By Fluorescent (3 Can, Cleaner, Developer, penetrent. )   

·         LT-            Leak Test        -           By Soap solution covered weld during testing.

·         Eddy current test               -           By supplying current

Destructive Test : This examination is carried out with destruction of materials. Following are the

            types of NDT.

·         Tensile Strength -

·         Hardness Test -     BHN – Brinell Hardness Number

RHN – Rockwell Hardness Number

            BEND TEST / ROOT BEND / FACE BEND

·         Toughness Test-    Charpy test                 

Q.38.   What do you understand by Position of weld?

Ans.     Relation between the weld pool, joint, joint member, and welding heat source during welding .(Work

            piece kept on different angle that is to be welded at site. According to position we decide to

engage qualified welders which based on capabilities. qualification of welders also depends                      

 upon the position of jobs).  Example

1G,2G,3G,4G,5G,6G,6GR

1F, 2F, 3F, 4F, 5F, 6F

Where,   G =   Grove weld and F=     Fillet weld.

IG        -           Flat

2G       -           Horizontal

3G       -           Vertical

4G       -           Overhead

5G       -           1G, 3G, 4G         

6G       -           @ 45°                                                  45•

6GR    -           @ 45° with Ring                                                        

                                                                   45•

Remarks:         Pipe welders are qualified in 6G Position. These welders will be qualified for all position except 6GR.

                        Structural welders are qualified in 3G & 4G. So that he will be qualified for all position of plate welding on site.

                        Plate welder can also weld for big bore pipe (above 24’’dia) as per ASME SEC.IX.

Q.39. What are the Shielding gases?               

Ans.     Argon, Carbon dioxide, helium and Nitrogen are the shielded gases used during welding.

Q.40. What is the abbreviation of OSHA?

Ans.     Occupational Safety and Health Act.

Q.41.   What do you understand by HOLD POINT?

Ans.     A specific, prearranged step in the fabrication process, where fabrication is stopped to permit an temporary inspection. Fabrication can be started again when the inspection shows the part meet the quality inspection.

Q.42.   Which type of tungsten electrodes are commonly used to weld of two ferrous materials.? and what the color code.?

Ans.     EWTh-2 (1.7 – 2.2 % thorium) with Red color.

Q.43.   How many types of joint is fabricated for welding.?

Ans.     Five types of Joint are basically fabricated for welding.

            BUT, CORNER, T , LAP, EDGE

Q.44.   What is psi?     

Ans.     Pound per square inch.

Q.45.   What is soldering?

Ans.     Soldering is the process of Joining two materials without melting BASE METAL with a filler of less melting point @450°C

Q.46.   what is WELD MAP.?

Ans.     Weld map is plotted in isometric drawing of pipe to show welding joint (Field/Shop).After welding these joints are highlighted and mentioned the following details.

            Date of weld completed.

            Welders Id No. Who has welded.

Q.47.   What are the important documents for welding?

            RFI (Fit-up / welding)

            Daily weld Production Report.(DWR)

            Weld map record in drawing / Register.

            WPQR (Welder procedure qualification record with Certification ID.

            Calibration certificate of Welding m/c and oven (Baking,holding,quivers etc).

            Test certificate of all filler metal.

Q.48.   How many are the types of weld.?

Ans.     Groove weld, Fillet weld, Slot or plug weld, spot weld, seam weld, back or backing weld, surfacing weld, edge weld.

Q.49.   Explain groove weld.

Ans.     A weld made a groove between the work piece. There are eight type of groove weld.

            SQUARE, SCARF,V, BEVEL, U, J, FLARE V, FLARE BEVEL.

Q.50.   Explain Fillet weld and sketch.?

Ans.    

       WELDING QUESTION AND ANSWER FOR WELDING FOREMAN/ SUPERVISORS

Q.1.     What is Welding ?

Ans.     Welding is process to joining Two Similar or dissimilar materials after heating with pressure or    

            without pressure.

Q.2.     What is difference between Pipe and Tube?

Ans.     Pipe is a tubular shape material which is used for transportation of fluid and Tube is used to transfer the Heat, Pipe is measured by NPS (dia) with schedule (Thk.)Where Tube is measured by OD.

Q.3      What are the Process of Welding.

Ans.     The following are the main welding process generally used for construction work.

            1.         SMAW            -  Shielded Metal Arc Welding.Also called Stick welding.

            2.         GTAW                        -  Gas Tungsten Arc Welding. also called Tig welding.

            3.         GMAW           -  Gas metal arc welding, also called CO2 Welding

            4.         FCAW            -  Flux Cored Arc Welding

            5          SAW               -  Submerged Arc Welding.

Q.4      What is WPS , PQR & WPQR?

Ans.     WPS    -           Welding Procedure Specification (A procedure before to start the welding)

PQR    -           Procedure qualification Record ( All variable record noted during qualification during                        

welding process)

           WPQR -           Welder Procedure qualification Record.( Variable recording during welders   

                                    qualification)

Q.5      What is difference between ELECTRODE and FILLER WIRE?

Ans.     Current passes through Electrodes and fused where as in filler wire Current Passes through Tungsten

            electrode and fused externally.

            Electrode is coated with flux which is prevent oxidation.

            Filler wire is barred and Inert gas used to prevent oxidation.

Q.6      Explain about the following codes.

            ASME, AWS, ASTM, ANSI, BS, ASNT, API,

Ans.     ASME -           American Society of Mechanical Engineer

            AWS   -           American Welding Society

            ASTM -           American Society Of Testing Materials

            ANSI  -           American national standard institute

            B.S     -            British Standard        

            ASNT -           American society of Non destructive Testing

            API     -           American Petroleum institute.

Q.7      Abbreviation of the following codes.

            ASME SEC II,V,VIII, IX

            API 1104                 

            D1.1

            B31.1, B31.3

Ans.     ASME SEC II -           Code of materials

            ASME SEC V -           Code of NDT

            ASME SEC VIII-       Code for construction of pressure Vessel

            ASME SEC IX-          Code of Welder Qualification/WPS/BAZING

            API-                            Cross Country Pipeline

            B31.1-                         Code of Power piping

            B31.3-                         Code of process Piping

            AWS D1.1                  Structural Welding

Q.8.  What is DCEN and DCEP?

Ans.   DCEN- Direct Current Electrode Negative – Straight Polarity- GTAW- More Heating of W/P

          DCEP -  Direct Current Electrode positive   _ Reverse Polarity- SMAW-More heating of Electrodes

          

Q.9. What is difference between TANK, BOILER and Vessel?

Ans. Tank is used for Storage where Vessel is used for Process and boiler is used for Steam generation.

Q.9  Explain Up-hill and Down-hill Progression?

Ans.     UP-Hill Progression - Welding in upward direction ↑

            Down-Hill                -  Welding in downward direction ↓

Q.10.  What is the number of protected Welding glass-Shade

Ans.     10,12,14

Q.11. MSDS?

Ans.  Material Safety data sheet.

Q.12 What is the purpose of Flux?

Ans.  Shielding, De oxidation , Ionizing, Alloying, Insulating .

Q.13. How will you identify L.H Electrode. (Low hydrogen electrode)

Ans.  Whose last number is 5,6,8 Example: EXXX5, EXXX6, EXXX8 (E7018)

Q.14, Explain about E7018 Electrode.

Ans.  This electrode is a Low hydrogen and having a good properties in all aspect and is used for dynamic

          loaded structural, Piping and equipment.This is used by the process SMAW

            E          -           Electrode

            70        -           Minimum Tensile Strength in Psi -    70000 psi

            1          -           Capabilities to weld in all position

            8          -           Electrical Characteristic / Flux coating

Q.15. Explain about ER70S-2 Filler wire.

Ans.  Filler wire is used for tig welding and this specification is for CS. Welding process for this is GTAW

            ER       -           Electrode Rod

            70        -           Tensile Stength in PSI- 70000 PSI

            S          -           Solid wire

            2          -           Chemical Composition.

Q.16. Explain about ER71T-1 Filler wire.

Ans.  Filler wire is used in rolled with fast production in fab.shop or site involved welding process FCAW welding and this specification is for CS.

            ER       -           Electrode Rod

            7          -           Tensile Stength in PSI- 71000 PSI

            T          -           Tubular filler wire

            1          -           Chemical Composition.

FCAW Process is self shielding because of flux inside of the tubular wire. It may or may not required any inert gas.

Q.17. What is P, A, and F Number?

Ans.     P-         Identification of Parent metal number

            A         Identification of Chemical composition of filler wire

            F          Identification of Filler metal number

Q.18. What type of gases is utilized for Shielding/ Purging?

Ans.     Argon, CO2, Nitrogen etc

            GTAW PROCESS  -  ARGON 15-25 PSI

            GMAW PROCESS-   CO2

Q.19. What is Pre-heating and PWHT?

Ans.     Preheating is done before welding to control cracking and porosity, min-150F above 19mm thk mtrl.

            If temp. observed below hand temp. 

            PWHT-POST WELD HEAT TREATMENT-

            PWHT is done after complete the welding (24-48 HRS) to release the stress induced during welding.

Q.20. How L.H Electrodes handle?

Ans. 

Baking @260-350 °C for 1-2 hrs.

                        ↓

Holding @120-149°C For 24 hrs.

                        ↓

Issue to Quivers @65-120 °C For 4-8 hrs.

                        ↓

Unused Electrodes For Rebaking.

Q.21. Important Documents file to be maintained for Electrode Handling System.

Ans.      Requisition form –Issuing filler metal

             Baking Record Book

             Holding Record Book

             Filler metal consumption record

             Mill test certificate record

             Calibration certificate of Oven.

Note:  All filler metal to be stock in dry, clean and humidity free area. Different Specification of Filler metal to be kept separate in rack and proper identification to be mark.SS and CS not to be kept in same place to prevent corrosion.

Q.22.   What is essential variable and Non essential variable in WPS?

Ans.     Variable that effect Chemical or Mechanical Properties of materials. Exp. Joint Design, Process, P or

F No changed, progression, Electrical characteristic etc.

Non-Variable that not effect Chemical or Mechanical Properties.Exp. Bevel angle, Diameter change,

Current fluctuation etc.

Q.23.   According to what codes welder qualification are carried out.

Ans.     ASME SEC IX – For process and power piping.

            API 1104           _ For Cross country pipeline

            AWSD1.1         _ For Structural

Q.24. What types of pipe is generally used in plant?

 Ans.  Manufactured wise

          Seamless Pipe, ERW Pipe (Seam pipe), Plastic pipe (GRE,FRB Etc)

          Materials wise

          Carbon steel (CS), Stainless steel (SS), Low temperature carbon Steel (LTCS), Duplex stainless steel     

          (DSS).

Q.25. What is Duplex Stainless steel (DSS)

Ans.   Combination of Austenite and Ferrite, Good mechanical Properties, Corrosion resistant, and

          capability to work in negative temp. Generally this pipe is used in Gas plant. This is magnetically

          attraction.

Q.26.  In welding where purging is required ?

Ans.   At the time of SS or DSS welding purging is required to prevent oxidation.

Q.27. How pipe joint is purged?.Up to what thickness purging is provided. What type of gas is    

          utilized.

Ans.  Argon gas is used for purging upto 6mm (Root+HP). We blocked about 100 mm away from the welding joint (inside pipe) by Paper Dam, Rubber Dam, Air balloon etc and passed the Argon gas through purging pipe connected with cylinder whose flow controlled according to the requirement. When Oxygen removed from the pipe joint area then welding started.

Q.28. How will you check the oxygen %age?

Ans.  Oxygen percentage is checked by Oxygen analyzer/ Oxygen purge monitor.

          FOR  SS            -           0.2 %  Oxy. max.

          FOR DSS          -           0.05 % Oxy.max. 

Q.29. Which types of fitting is utilized in piping?

Ans.  Elbow, Flange, Tee, Socket, Blind, Nipple, Valve, Nut Bolt, Gasket, Expansion below etc.

Q.30. Explain Types of Valve.

Ans.      Isolation Valve- To stopped the fluid flow. Example Gate Valve.

            Regulation Valve-To regulate the valve as per required flow- Example Glob Valve.

            Non Return Valve- To flow the fluid in one direction only- Exp. Check Valve

            Special Purpose Valve- This valve is used as per special requirement as below

To release high pressure – Exp. Safety valve,

To release air -           Air release Valve

Auto flow control-      Control valve

             

 Q.31. How you will select Filler Metal?

Ans. Filler metal selection is always on the base of Materials specification. Which is described some of the

         important selection of filler metal as below.

Parent Materials	P. No.	Filler Metal		Process	Material-Material
		Root	Fill up & Capping
ASTM-SA106 Gr.B ASTM-SA285 Gr.C ASTM-SA516 Gr.70	P1	ER70S-2	E7018	GTAW + SMAW	CS-CS
ASTM A312 TP304L F182 304L	P8	ER308L	E308L	GTAW + SMAW	SS-SS
ASTM A312 TP316L TP321,A182,F321,A358	P8	ER316L	E316L	GTAW + SMAW	SS-SS
ASTM A333 GR-6, A350,LF2,A420 WPL6	P1	ER80SNi-1 ER80SNi-2	E7018-1 E7081-C1	GTAW + SMAW	LTCS-LTCS
SA335 Gr.P11 SA213 Gr.P11	P4	ER80S-B2	E8018-B2	GTAW + SMAW	Alloy steel to Alloy steel
ASTM A335 Gr.P22 SA182 Gr.P22	P5A	ER90S-B3	E9018-B3	GTAW + SMAW	Alloy steel to Alloy steel
SA 335 GR.P91	P5B	ER90S-B9	E9015-B9	GTAW + SMAW	Alloy steel to Alloy steel
ASTM-SA106 Gr.B ASTM A312 TP304L	P8-P1	ER309 ERNiCr-3	E309 ENiCrFe3	GTAW + SMAW	CS-SS
BRAZING B88-Gr102		BCuP-2		OXY-ACETYLENE	CU

    DSS FILLER WIRE – ER2209 & ELECTRODE IS E22

    Electrode E6010 is used for root welding and suitable good for big bore, E6013 is also used for general  

    purpose work like light structure, water pipe etc.

Remarks,:  If the materials grade changed of the same specification then we select the higher one. exp.  

                      ASTM A312 TP304L& ASTM A312 TP316L to be welded then we use ER316L Filler wire.

                        Preheating is required in all Alloy joint where welding is to be carried out.@210 *C

                        PWHT is required after welding in alloy steel.

Q.32. What is the formulae to calculate of Electrodes quantity?

Ans.     W=      D X A X L

                        Efficiency                        Where,

W=      Weight of Electrode / wire in KG

D=       Density of Weld metal kg/m3

ρ =       density of steel = 7780 kg/m3 at 20 0C

A=       Cross sectional area of joint (m2)

L=       Length of joint

Efficiency,

SMAW=0.65,             GTAW=1.00,              GMAW=0.95,             SAW=1.00

Q.33. sketch & explain the following Pipe joints.

Parts of weld joints:-  Joint root, grove face, root face,  root edge, root gap, bevel , bevel angle, groove angle, grove radius etc.

Q.34. Explain defects of Welding, Cause and remedies.

Ans. 

DEFECTS	REASON/CAUSE	PREVENTION
Lack of fusion (Parent Material not fused in root or weld face)	Weld face more, Speed travel more, No root gap proper etc.	Joint should be as per WPS
Lack of Penetration (Incomplete root penetration)	Narrow root gap, Unskilled welder, Low current etc.	Proper skilled welders and current is required as per WPS.
Crack (Occur linear mark in welding or Heat effected zone)	Fast cooling process, improper tacking and supporting etc.	Proper heat treatment is required
Slag (When flux entrapped in molten metal during welding)	Not proper cleaning in between layers, Wet electrodes etc.	Need Proper cleaning.
Spatter (Excess materials spread on parent metal without fuse during welding)	High current, Barred electrode etc.	Proper current to maintain.
Arc Strike (When spark occur on pipe by electrodes/ holder )	Un skilled welders,	Need precaution, spark should not be on the pipe)
Porosity (A round spherical shape entrapped in molten metal)	Due to high current, wet electrodes, more wind pressure etc	To be minimize all these things.
Undercut (Cut appear in toe)	Due to high current.	To maintain current

           

Q.35.  What is Weld Affected Joint (HAZ)

Ans.    Parent materials whose atomic structural changed during welding is called HAZ. Up to. 2’’from weld toe.

Q.36.  What are the inspection Method of welding.

Ans.  Basically there are two method for examination of welding as below.

            NDT    -           Non destructive Test

            DT       -           Destructive Test.

Q.37.  Explain NDT & DT Methods.     

Ans.     Non destructive Test : This examination is done without destructive of materials, Following are the

            types of NDT.

·         VT-            Visual Test

·         RT -           Radiography Test. – Carried out by isotopes. (Gama ray)

·         UT-            Ultrasonic Test            _ By ultrasound wave m/c

·         MPT-         Magnetic Particle Test- By Magnet (Flux flaw)

·         DPT-         Dye Penetration Test-   By Fluorescent (3 Can, Cleaner, Developer, penetrent. )   

·         LT-            Leak Test        -           By Soap solution covered weld during testing.

·         Eddy current test               -           By supplying current

Destructive Test : This examination is carried out with destruction of materials. Following are the

            types of NDT.

·         Tensile Strength -

·         Hardness Test -     BHN – Brinell Hardness Number

RHN – Rockwell Hardness Number

            BEND TEST / ROOT BEND / FACE BEND

·         Toughness Test-    Charpy test                 

Q.38.   What do you understand by Position of weld?

Ans.     Relation between the weld pool, joint, joint member, and welding heat source during welding .(Work

            piece kept on different angle that is to be welded at site. According to position we decide to

engage qualified welders which based on capabilities. qualification of welders also depends                      

 upon the position of jobs).  Example

1G,2G,3G,4G,5G,6G,6GR

1F, 2F, 3F, 4F, 5F, 6F

Where,   G =   Grove weld and F=     Fillet weld.

IG        -           Flat

2G       -           Horizontal

3G       -           Vertical

4G       -           Overhead

5G       -           1G, 3G, 4G         

6G       -           @ 45°                                                  45•

6GR    -           @ 45° with Ring                                                        

                                                                   45•

Remarks:         Pipe welders are qualified in 6G Position. These welders will be qualified for all position except 6GR.

                        Structural welders are qualified in 3G & 4G. So that he will be qualified for all position of plate welding on site.

                        Plate welder can also weld for big bore pipe (above 24’’dia) as per ASME SEC.IX.

Q.39. What are the Shielding gases?               

Ans.     Argon, Carbon dioxide, helium and Nitrogen are the shielded gases used during welding.

Q.40. What is the abbreviation of OSHA?

Ans.     Occupational Safety and Health Act.

Q.41.   What do you understand by HOLD POINT?

Ans.     A specific, prearranged step in the fabrication process, where fabrication is stopped to permit an temporary inspection. Fabrication can be started again when the inspection shows the part meet the quality inspection.

Q.42.   Which type of tungsten electrodes are commonly used to weld of two ferrous materials.? and what the color code.?

Ans.     EWTh-2 (1.7 – 2.2 % thorium) with Red color.

Q.43.   How many types of joint is fabricated for welding.?

Ans.     Five types of Joint are basically fabricated for welding.

            BUT, CORNER, T , LAP, EDGE

Q.44.   What is psi?     

Ans.     Pound per square inch.

Q.45.   What is soldering?

Ans.     Soldering is the process of Joining two materials without melting BASE METAL with a filler of less melting point @450°C

Q.46.   what is WELD MAP.?

Ans.     Weld map is plotted in isometric drawing of pipe to show welding joint (Field/Shop).After welding these joints are highlighted and mentioned the following details.

            Date of weld completed.

            Welders Id No. Who has welded.

Q.47.   What are the important documents for welding?

            RFI (Fit-up / welding)

            Daily weld Production Report.(DWR)

            Weld map record in drawing / Register.

            WPQR (Welder procedure qualification record with Certification ID.

            Calibration certificate of Welding m/c and oven (Baking,holding,quivers etc).

            Test certificate of all filler metal.

Q.48.   How many are the types of weld.?

Ans.     Groove weld, Fillet weld, Slot or plug weld, spot weld, seam weld, back or backing weld, surfacing weld, edge weld.

Q.49.   Explain groove weld.

Ans.     A weld made a groove between the work piece. There are eight type of groove weld.

            SQUARE, SCARF,V, BEVEL, U, J, FLARE V, FLARE BEVEL.

Q.50.   Explain Fillet weld and sketch.?

Ans.