welding expertise

Maintenance welding

Majority of industrial sectors: power,transportation,construction,piping,defence,aero space,castings,forgings and general fabrication are involved in maintenance welding.Thorough knowledge helps to successfully complete given task.

fig 1. Forging repair :Metal to metal wear

Hardfacing for better maintenance welding

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Hard-facing  protects parts against wear and ensures certain specific wear resistance or properties.

https://youtu.be/9R_pzbIGfJI

• Welding processes
  The most common processes  are:
  Shielded Metal Arc Welding, SMAW
  Also known as Manual Metal Arc Welding (MMA)
  • covers the widest range of weld metals
  • is inexpensive
  • is a versatile process used outdoors and for out-of-position work.   https://youtu.be/xL0nvZ1F47Q
• Flux-Cored Arc Welding, FCAW
  • alloy availability almost the same as covered electrodes • high deposition rate
  • can be used on site due to open arc operation
  • self-shielding, no extra gas is needed
  Submerged Arc Welding, SAW
  • limited range of products
  • high deposition rate – to rebuild large worn parts • no arc flash or spatter
• Gas welding also continues to be used for some applications.
• Wear factors
  A large number of different wear factors exist. Consequently,  weld metals must be used with caution to meet specific use.
  For example; when examining a part, it is determined that the primary wear factor is abrasion and the second is moderate impact. The hard-facing alloy should have very good abrasion resistance but also reasonable impact resistance.
• Wear from metal parts such as shafts against bearing surfaces, chain links against a roll, sprockets, steel mill rolls require
  Martensitic hard-facing alloys ,
  Austenitic-manganese and cobalt alloys are also good ,
  Cobalt alloys are used in high-temperature and oxidation environments.
• contact between  materials of the same hardness ,result in excessive wear.

Classification of weld metals.

iron-based:
• martensitic alloys • austenitic alloys
• carbide-rich alloys
non-iron-based:
• cobalt-based alloys • nickel-based alloys
For wear applications.
martensitic:
Both for building up and surfacing: • good metal-to-metal resistance
• good impact resistance
• fair abrasion resistance
austenitic:
• excellent impact resistance • good build-up alloy
• fair abrasion resistance
carbide-rich:
• excellent abrasion resistance • good heat resistance
• fair corrosion resistance
• poor impact resistance
cobalt- & nickel-based
Most types of wear, but, due to their higher cost, they are mainly used in applications in which their properties can be economically justi- fied, such as high-temperature applications in which carbide-rich, iron-based alloys have a low resistance. Nickel alloys are the cheaper alternative

welding expertiseFrequently asked questions and answers give enormous knowledge power to face challenges and better understanding.

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Welding reviews

A)Welding processes-Knowledge power for solutions

 

Welding Knowledge power on welding processes is key for success in fabrication.

1.What are the examples for homogenous welding.

SMAW,GTAW,GMAW,SAW,EGW,ESW with matching filler addition.

2.Why TIG welding is preferred for good quality welds.

Aero space applications require

Zero defect and use Titanium alloys and aluminium alloys. TIG

welding with extra purity Argon shielding provides highly reliable joints.

3.Why synnergic MIG is useful .

Thin sheet welding in critical applications can be welded without the problem of burn through.

4.what are the methods to control arc blow in DC welding.

a. Make sure the ground is properly located on the work. Placing the ground in the direction of the arc deflection is helpful.
b. Separating the ground into two or more parts is helpful.
c. Weld towards the direction in which the arc blows.
d.Maintain a short arc.
e. Changing the angle of the electrode relative to the work may help to control the arc.
f. Magnetic blow is minimum in alternating current welding.

5.Which automatic  processes are employed for welding plates in vertical direction

Electro slag and electro gas processes can be used for vertical welding of plates.Ship building ,storage tanks,and pressure vessels find good use.

6.Why SAW is preferred for thick plates in flat position.

Multi layer welds in thick plates give better toughness due to grain refinement of previous layer by subsequent layer.

7.Which shielding gas is used with MIG for stainless steels when using DC +

Argon +1%oxygen to eliminate undercutting

8.When argon+5% oxygen is used for stainless steel MIG

For Dc –  ve  welding to improve arc stability.

9. Why  GMAW with carbon dioxide requires deoxidisers in wire such as.

Si,Mn,Ti,V react with oxygen and protect weldmetal to improve quality

10.Which gas mixture gives best quality welds with flux cored arc welding

75% argon +25% carbon dioxide

11.What is the maximum inter pass temperature for carbon steel submerged arc welds.

260 deg.C

12.When basic fluxes are used.

Basicity has great influence on impact toughness of the weld metal. Increasing basicity brings down the oxygen content and hence the inclusion level in the weld metal. Consequently, the impact toughness will increase and also, to a limited extent, the ductility of the weld metal.

The relation between basicity and impact toughness is particularly important for high alloyed grades, such as duplex steels.

13.Which process can be used for inconel overlaying of tube sheet for nuclear steam generator.

Submerged arc strip cladding process can be used with wide strip.Electroslag strip cladding process also is another method.

14.What is the best process for managing steel welding required for aero space applications.

GTAW with continuous wire addition can be used with special purpose

system.

15.Which process is good for  pipeline welding of large diameters for various medium applications.

Orbital GMAW special purpose welding equipment finds great use with higher productivity

16.What process is ideal for welding very large thicknesses .

Narrow gap submerged arc welding with special J type edge preparation provides less weld metal and better impact strength.Grain refinement takes place by the subsequent passes in multi layer welding.

17.Which electrode gives good deposition rate and quality welds for low carbon steels.

E7018 is ideally suited for improving productivity and avoiding cold cracking tendency.

18.Which electrode gives better performance for welding austenitic stainless steel and low carbon steel.

E309 electrode is good for crack free welds.

19.Where is sodium titanate used.

Electrode coatings use for good quality and arc stability.

20.What is the use of cellulose coated electrodes.

Deep penetration electrode used for structural fabrication,pipes and repair works.

21.Which electrodes are suitable for flat and horizontal welding positions.

E 6020,E6027,E 7024,E7027,E7028 are suitable .

22.Which electrode is preferred for welding low carbon steel to austenitic stainless steel.

E 309 is compatable to both metals.

Affordable Online up-skill welding courses

1.Affordable On-line up-skill welding courses .

These affordable courses on  welding technology are essential as it is a complex technology involving all disciplines of engineering : Mechanical,metallurgical,electrical,electronics,civil,computer science and production .Practicing   engineers find short term online up skill specialised welding courses useful for refreshing and to implement in industries latest trends.

Latest trends

Welding Education and training

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http://www.aws.org.com

http://www.iiw.com

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2. Course titles:Eligibility,Contact mail

The following programmes will be conducted online for small batches for better interaction and to gain in depth knowledge.

1. Welding process technology I     2 days ( 6 hrs per day) Saturdays and Sundays

All arc welding processes required for industries will be covered.

2.Welding process Technology II     2 days ( 6 hrs per day) Saturdays and Sundays

3.Design ,distortion,and control     2 days

4.Weldability of ferrous and non ferrous alloys  2 days

All other advanced welding processes are covered with applications.

Experienced candidates with diploma, engineering qualification  as well as fresh engineering graduates(3 and 4 sem) from India can apply .

Interested candidates can contact for getting details of fees and schedule .Group booking can be done as per guidelines.Link will be provided in advance for attending online courses as per schedule.

Mail address for contact :

kgk.murti@gmail.com

3. Schedule

The number of candidates per course is limited to maximum 15.

 

4.Benefits

These courses will be useful also  as preparatory courses for Welding engineers and welding inspector certification programs.

5.Faculty:

Dr.KGK Murti

Qualification : B Tech (Mech);M Tech ( welding);IIT Chennai.P h.D

(welding) NIT Trichy.

Experience: 30 years in Welding research institute and BHEL Trichy.

Trained in Germany,France.Visited Russia and Japan

Presented more than 80 papers and guided 6 Ph.D welding students

Worked as professor for 15 years in GRIET,IARE Hyderabad.Won several awards during the last 45 years of experience in industry and academics.

6.Purpose of affordable on-line Up-skill welding courses.

These courses are planned as no loss no profit basis to promote

welding technology and benefit welding professionals.

Several week end courses are planned on all major topics.Those interested can communicate giving topics of current interest to include.Certificate will be given on successful completion of course which will be useful for resume and placements.

Welding placements and skills needed
Welding professionals are always needed in industries for both shop floor and site welding jobs.

Welders skill requirements

1. Welding process knowledge(SMAW,GMAW,GTAW etc)

2.Basic metallurgy( Metals,non-metals,physical and mechanical properties,Metallography,HT etc)

3.Design of welds( Edge preparation, welding symbols,types of welds,plate and pipe welds,welding positions etc)

4.Destructive tests for evaluation of weld quality

5.Non destructive tests and applications.

6.Basic mathematical skills(calculating dimensions,understanding sketches,reading drawings,2D,3D,spatial reasoning)

7.Attention to detail( material preparation,cleaning,perfection in workmanship,etc)

8.Hand- eye coordination

9.Stamina to work in various situations

10.Ability to learn new things

11.Communication skills and team working .

12.Welding health and safety.

13.Codes and standards knowledge

14.Welding defects and acceptance criteria.

Those with sufficient training,adequate qualification and certification  can prepare a good resume and apply for posts regularly announced through important websites.

http://www.naukri.com

http://www.careers in welding.com

http://www.placementindia.com

Certified welding engineers

International institute of welding offers certified welding engineers programme which is recognised in many countries.

IWE : International welding engineer (IIW)
IWE – Knowledge, Competence and Management
A candidate completing the IWE training under this program is expected to acquire advanced knowledge and critical understanding of welding technology application.
He / she shall have advanced competence and skills at a level that is required in the field of welding technology which demonstrate:

1.Technology mastery and required innovation

2.Being able to solve high-level complex and unpredictable problems
3. The ability to manage high complex technical and professional activities or projects related to welding applications
4.Taking responsibility for decision making in unpredictable work or study context
5. Taking responsibility for managing professional development of individuals and groups

Thoretical and practical sessions to give in-depth knowledge are offered .Four modules have to be completed and examination will be conducted after each module.

Module 1: Welding processes and equipment.

Module 2: Materials and behaviour during welding

Module 3:Construction and design

Module 4:Fabrication and application engineering

After successful completion of all the modules ,certificate will be issued (IWE)

AWS certified welding engineer(CWEng)

A person with the demonstrated education, experience, and knowledge as defined by this information and who successfully passes the required examinations is considered qualified as an AWS Certified Welding Engineer (CWEng).

The CWEng is capable of directing those operations associated with weldments and other types of joints that are completed in accordance with the appropriate contract documents, codes, and other standards to produce a satisfactory product. The welding engineer¹s activities begins before production or construction welding and continues through the production process then ending when the production process is complete.

Each employer is responsible for defining the specific duties of the CWEng in place of employment.

Great opportunities exist for AWS certified welding engineers all over the world.

Certified welding inspector(CWI)

Certified Welding Inspectors (CWI) must demonstrate a keen attention to detail along with other requisite knowledge, skills, and abilities, and are often considered the safety nets that catch potentially catastrophic mistakes.

It’s the CWI’s responsibility not only to determine if a weldment meets the acceptance criteria of a specific code, standard, or other specification, but also to handle qualification records, oversee non-destructive testing and ensure proper materials are available during testing.

Therefore, it is important that the CWI is familiar with welding processes, welding procedures, welder qualifications, materials, and weld testing limitations, as well as how to read blueprint drawings, prepare and keep records, prepare and make reports, and make responsible judgments.

AWS gives CWI which is very valuable and recognised in many countries.

CSWIP welding inspector

LATEST  Trends in welding technology

Read More

 

Welding codes and standards

Welding professionals should possess knowledge on various codes

and standards for successful fabrication of products.Some important codes and standards have world wide acceptance.Wealth of information by experts  is incorporated in these reference materials.

 

http://www.asme.org

http://www.api.org

 

http://www.aws.org

http://www.iso.org

Approach for preparation of codes and standards

AWS Standard Welding Procedure Specification (SWPS)

Procedures that have been qualified by the Welding Research Council and accepted and published by AWS for use as a qualified welding procedure

Welding Education and training

Welding Procedure Qualification (PQR)

A test that is performed to demonstrate that the contractor can make satisfactory welds as specified in the Welding Procedure Specification

Mechanical testing is required and NDE may be required, depending on the Code being qualified to
Impact testing may be required by the referencing Code (i.e., ASME Sect VIII)

Guidelines for Quality records

Quality records shall be retained for a minimum period of five years in the absence of any other specified requirements.
Quality records shall include, when applicable:
– record of requirement/technical review;
– material certificates;
– welding consumable certificates;
– welding procedure specifications;
– equipment maintenance records;
– welding procedure approval records (WPQR);
– welder or welding operator qualification certificates;
– production plan;
– non-destructive testing personnel certificates;
– heat treatment procedure specification and records;
– non-destructive testing and destructive testing procedures and reports;
– dimensional reports;

Welding Tips for practice                

1 Mild steel electrodes:E 6010,E6011,E6012,E6013
2.Use DCEP for E6010 when used for mild steel and
low alloy steels required for ship building,construction,bridges,tanks,piping.
3.AC/DC can be used for E6012 for flat and horizontal positions.
4.Use E6012 when fitup is a problem.
5.E6013 can be used with AC/DC and has very good
slag detachability.Sheet metals are welded very well.
6.E7016 is used for hardenable steels when preheat and stress relieving cannot be performed.
7.E7018 which is a low hydrogen iron powder all position electrode can be used for radiograph quality welds.
8.Arc striking with scratch method in the direction of welding is to followed.
9.Use AC to prevent arc blow problem.

10.Use short arc and low current for horizontal position welding.
11.Use whipping motion in the direction of welding for vertical uphill welding.
12.Use constant current power source with 60%duty cycle at maximum current.
13.Transformer sets are useful for all types of structural fabrication.
14.Arc blow problem can be avoided by using AC transformer sets.
15.Motor Generator sets are useful for all types of fabrication in workshops and site work.
16.Inverter sets are highly portable and can be used for all types of fabrication.

Factors to be understood for cooling rate control for weld,HAZ

1. Preheat and interpass temperature
2. Material thickness
3. Heat sinks – presence of chill bars or other ways to drive heat away from the welded part
4. Heat input from welding – certain process, such as submerged arc welding, can have high enough heat inputs that make preheat not necessary
5. Use of cooling blankets
6. Ambient conditions (ambient temperature)
7. Quenching (air, water, oil, furnace).
   

Electrode wrong polarity will result in:
– excess spatter and poor penetration
– improper fusion of the electrode
– heavy brownish deposition on the face of the weld metal
– difficulty in manipulation of the arc
– abnormal sound of the arc
– poor weld bead appearance with surface defects and more spatter.

Arc blow control techniques in DC

1. Placing workpiece lead connections as far as possible from the joints to be welded;
2. If back blow is the problem, placing the work- piece connection at the start of welding, and welding toward a heavy tack weld;
3. If forward blow is causing trouble, placing the workpiece connection at the end of the joint to be welded;
4. Positioning the electrode so that the arc force counteracts the arc blow;
5. Using the shortest possible arc consistent with good welding practice to help the arc force coun- teract the arc blow;
6. Reducing the welding current;
7. Welding toward a heavy tack or runoff tab;
8. Using the backstep sequence of welding;
9. If backing is used, welding the entire length of
the backing to each base plate;
10. Changing to alternating current, which may
require a change in electrode classification; and
11. Wrapping the workpiece lead around the work- piece in a direction so that the magnetic field it sets up will counteract the magnetic field causing
the arc blow.

Welding Education and training

 

                                                   Bibliography

List of important reference articles collected from Bibliography sources.

[1] British Standards Institution, 1983 BS 499: Part 1 (Welding Terms and Symbols, Glossary of welding, brazing and thermal cutting).
[2] American Welding Society, 1989 Welding Handbook, vol 1, Welding Technology, 8th edn, Miami, AWS.
[3] International Standards Organisation, ISO 4063, 1998 Welding and allied processes – Nomenclature of processes and reference numbers.
[4] Bay N, 1986 ‘Cold welding’, pts 1–3, Met Constr, 18(6, 8, and 10).
[5] Benn B, 1988 ‘Friction welding of butt joints for high duty applications’, Weld
Met Fabric, August/September, 56.
[6] Nicholas E D and Teale R A, 1988 ‘Friction welding of duplex stainless steel’,
Offshore Technology conf, Houston, TX, 2–5 May 1988.
[7] Nicholas E D, 1982 ‘A friction welding application in the nuclear power industry’,
Weld Inst Res Bull, 23(1).
[8] Essa A A and Bahrani A S 1989 ‘The friction joining of ceramics to metals’,
Proc int conf on the Joining of Materials, JOM-4, Helsingor, Denmark, 19–22
March.
[9] Thomas W M et al. 1984 ‘Feasibility studies into surfacing by friction welding’,
TWI Res Rep, 236, Cambridge: The Welding Institute.
[10] Nicholas D and Watts E, 1990 ‘Friction welding – a sparkling success’, Weld
Inst, Connect, (8) April
[11] Bartle P M, 1983 ‘Diffusion bonding – principles and applications’, Weld Inst
Res Bull, 24(3).
[12] Johnson K I et al. 1979 ‘MIAB welding, principles of the process’, Met Constr
11(11).
[13] Edson D A, 1983 ‘Application of MIAB welding’, Proc Conf Developments and
Innovations for Improved Welding Production, The Welding Institute, Birmingham,
England, 13–15 Sept.
[14] Smith D S, 1989 ‘Control of quality and cost in fabrication of high integrity
pipework systems’, Proc Weldfab Midlands seminar, 25–26 Oct.
[15] 1989 ‘Control of welding – welding procedures, basic welding data, No. 11’,
Weld Metal Fabricat, 57(10).
[16] Salter G R, 1970 ‘Introduction to arc welding economics’, Metal Construct Br
Weld J, June.

[17]Lundin CD, Khan KK. Fundamental Studies of the Metallurgical Causes and Mitigation of Reheat Cracking in 1.25Cr–0.5Mo and 2.25Cr–1Mo Steels. WRC Bulletin No. 409. New York: Welding Research Council; 1996.

[18]Meitzner CF, Pense AW. Stress-relief cracking in low-alloy steel weldments. Weld J 1969;48 (10):431s–440s.

[19]Thomas RD Jr. HAZ cracking in thick sections of austenitic stainless steels, Part 1. Weld J 1984;63 (9):24–32.
[20]ThomasJrRD. HAZ cracking  in thick sections of austenitic stainlesssteels,
Part2.WeldJ 1984;63 (9):355s–368s.

[21]Curran RM, Rankin AW. Welding Type 347 stainless steel for 1100°F turbine operation. Weld J 1955;34 (3):205–213.

[22]Thomas Jr RD, Messler Jr RW. Welding Type 347 Stainless Steel: An Interpretive Report. WRC Bulletin No. 421. New York: Welding Research Council; 1997.

[23]Dupont JN, Lippold JC, Kiser SD. Welding Metallurgy and Weldability of Nickel Base Alloys. Hoboken, NJ: Wiley and Sons, Inc; 2009. p 364–367.

[24]CoeFr.WeldingSteelswithoutHydrogenCracking.Cambridge,Uk:WeldingInstitute;1973.

[25] ISo 17642-3:2005. Destructive tests on welds in metallic materials—Cold cracking tests for weldments—Arc welding processes—Part 3: Externally loaded tests. 1st edn: International organization for Standardization, geneva, Switzerland; 2005.

[26]National Electric Manufacturers Association (NEMA), Electric arc welding power sources, EW1. Rosslyn, Virginia: National Electric Manufacturers Association.

[27]Jackson, C. E. 1973. Fluxes and slags in welding. Welding Research Council Bulletin 190. New York: Weld-
ing Research Council.

[28]Stout, R. D., C. W. Ott, A. W. Pense, D. J. Snyder, B. R.
Somers, and R. E. Somers. 1987. Weldability of
steels. New York: Welding Research Council.

[29]International Institute of Welding. 1984. The Physics of Welding. Ed. J. F. Lancaster. Oxford, U.K.: Pergamon Press.

[30]Salkin, J. T. 1997. Rotating tungsten narrow groove GTAW—a summary of process development, capabilities, and applications. Proceedings of the EWI International Conference on Advances in Weld- ing Technology. Columbus, Ohio: Edison Welding Institute.

[31]Smith, J. S., et al. 1986. A vision-based seam tracker for TIG welding. Computer Technology in Welding. Cambridge, U. K.: The Welding Institute.

[32]Altshuller, B. 1998. A guide to GMA welding of alumi- num. Welding Journal 77(6): 49.

[33]Baujet, V., and C. Charles. 1990. Submarine hull construction using narrow-groove GMAW. Welding Journal 69(8): 31–36.

[34]Bruss, R. A. 1996. Designing GMA welding guns with the welder’s comfort in mind. Welding Journal 75(10): 31–33.

[35]Jonsson, P. G., A. B. Murphy, and J. Szekely. 1995. The influence of oxygen additions on argon-shielded gas metal arc welding processes. Welding Journal 74(2): 48-s–58-s.

[36]Kim, Y. S., and T. W. Eagar. 1993. Metal transfer in pulsed current GMAW. Welding Journal 72(7): 279-s– 287-s.

[37]Kim, Y. S., and T. W. Eagar. 1993. Analysis of metal transfer in gas metal arc welding. Welding Journal 72(6): 269-s–278-s.

[38]Nadeau, F. 1990. Computerized system automates GMA pipe welding. Welding Journal 69(6): 53–59.

[39]Sampath, K., R. S. Green, D.A. Civis, B. E. Williams,
and P. J. Konkol. 1995. Metallurgical model speeds development of GMA welding wire for HSLA steel. Welding Journal 74(12): 69–76.

[40]Kim, Y. S., and T. W. Eagar. 1993. Analysis of metal transfer in gas metal arc welding. Welding Journal 72(6): 269-s–278-s.

[41]Kimura, S., I. Ichihara and Y. Nagai. 1979. Narrow-gap gas metal arc welding process in flat position. Welding Journal 58(7): 44–52.

[42]Mitchie, K., S. Blackman, and T. E. B. Ogunbiyi. 1999. Twin-wire GMAW: process characteristics and applications. Welding Journal 78(5): 31–34

[43]Sadler, H. 1999. A look at the fundamentals of gas metal arc welding. Welding Journal 78(5): 45–47.

[44]Lathabai, S. and R. D. Stout. 1985. Shielding gas and heat input effects on flux cored weld metal properties. WeldingJournal. 64(11):303-s-313-s.

[45]Liu, S. 1998. Arc welding consumables-covered and cored electrodes: a century of evolution. ASM Con- ference Paper: Trends in Welding Research. (6)1998. Materials Park, Ohio: ASM International.

Welding Research

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