This document provides a summary of an internship report at Nepal Hydro and Electric Limited (NHE). It describes the practical work done in various departments including the turbine section, service and maintenance division, quality assurance processes, welding techniques, and the electrical division. The internship focused on gaining hands-on experience in repairing and maintaining hydro-mechanical equipment. Key activities observed and learned included turbine repair methods, preventative maintenance practices, non-destructive testing of welds, welding codes and standards, and transformer maintenance procedures. The report aims to provide insight into the various operations at NHE through documentation of the internship experiences.

1. INTERNSHIP
REPORT AT NHE
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Abstract
This report especially elaborates the practical
approach to hydro mechanical work that is performed
inside the NHE. It includes all the theoretical
knowledge and practical approach that I have learned
during my internship period.

2. i
ABSTRACT
This report contains brief description of the 18 days Internship program inside Nepal Hydro
and Electric Limited. This report especially elaborates the practical approach to hydro
mechanical work that is performed inside the NHE. It includes all the theoretical knowledge
and practical approach that I have learned during my internship period. It gives an insight into
organization structure along with its brief introduction. Every effort has been made to include
the manufacturing and repair and maintenance jobs that are in general the major tasks
performed.
All the activities performed at NHE have been documented under different departments for
clear understanding. In short, this report has been perfectly orchestrated to give the header a
brief understanding of the organization along with its field experience.
A workshop was held to identify the welding and joining needs of the Hydro power-related
industries, and to discuss the opportunities afforded these industries to solve the needs by
applying new methodology and knowledge available from the research establishment.
Specific opportunities were matched to specific needs to suggest project areas where research
and development would make contributions providing major technological impact. Among
the emerging new welding technologies, stick arc welding is used frequently for welding of
high strength Iron alloys such as Cast Iron, Stainless Steel and Mild steel etc. which are weld
by conventional fusion welding techniques. The project aims to weld the two different
thickness metals and check the maximum possible thickness of the welding.

3. ii
ACKNOWLEDGEMENT
It is indeed a great pleasure and privilege to present this report on training at NEPAL
HYDRO POWER AND ELECTRIC LIMITED.
I am extremely grateful to my Head of the Department and Training, Mechanical Division
Manager for issuing a training letter, which made my training possible at Nepal Hydro and
Electric Limited.
First, I thank the HR Head, MR. Deepak Sharma for considering my potential in doing this
training and providing this wonderful opportunity.
I would like to express my gratitude to MR. Bishal Humagai and MR. Bibek Bhattarai for his
invaluable suggestion, motivation, guidance and support throughout the training. Their
methodology to start from simple and then deepen through made us to bring out this project
report without anxiety.
Thanks to Mr. Khim Thapa and all the NHE officials, operators and all other member of
NHE, yet uncounted for their help in completing the project and see the light of success. We
are very thankful to friends, colleague and all other persons who rendered their assistance
directly or indirectly to complete this program successfully.
Date: 2080/07/13 Amit Gyawali (PAS076BME005)
Bikram Gautam (PAS076BME014)

4. iii
OBJECTIVES
The main objectives of the Internship are: -
 To become acquainted with the future field of the mechanical engineering student.
 To apply the acquired knowledge and skills in a practical situation.
 To become acquainted with real life problem solving.
 To work independently.
 To know about role of quality management system and its important in hydro power sector.
 To learn how to plan things out carefully.
 To develop social and communicative skills.
METHODOLOGY
 Visual Method
Different departments were and visual observation of different process of fabrication, repair,
maintenance, and machining were made. Different type of equipment machines along with
their working was visually observed.
 Conversation with Employees
Details of the process and machines were obtained from the conversation made with the
employees of the department. An oral interview was taken with the supervisor and
department managers.
 Secondary Sources
NHE brochures, website, project, and report were used to obtain the details and information.

5. iv
TABLE OF CONTENTS
ABSTRACT .......................................................................................................................................
ACKNOWLEDGEMENT ................................................................................................................ii
OBJECTIVES..................................................................................................................................iii
METHODOLOGY ..........................................................................................................................iii
LIST OF ABBREVIATIONS ........................................................................................................viii
LIST OF FIGURES .........................................................................................................................ix
LIST OF TABLES...........................................................................................................................xi
CHAPTER-1: INTRODUCTION .....................................................................................................1
1.1 Background of NHE................................................................................................................1
1.2 Company Objectives ...............................................................................................................1
1.3 Capabilities of NHE ................................................................................................................2
1.4 Mission and Vision .................................................................................................................2
1.5 Organizational Structure..........................................................................................................2
CHAPTER-2: Hydroelectric Power Plant..........................................................................................3
2.1 Types of Hydroelectric Plant ...................................................................................................3
2.1.1 Based on Power Generation..............................................................................................3
2.1.2 Based on Storage..............................................................................................................3
2.1.3 Based on Head Available..................................................................................................3
2.2 Essential Components .............................................................................................................3
2.3 Safety Engineering ..................................................................................................................4
2.3.1 Effects of Non-ionizing Electromagnetic Fields on Human Body .....................................5
2.3.2 Physical Effects of Electric Shocks...................................................................................5
2.3.3 Safety and Precautions......................................................................................................6
Chapter-3: Service Division..............................................................................................................9
3.1 Turbine Section.......................................................................................................................9
3.1.1 Process for Repairing........................................................................................................9
3.1.2 Repair Methods .............................................................................................................. 10
3.2 Service and Maintenance....................................................................................................... 11
3.2.1 Preventive Maintenance.................................................................................................. 11
3.2.2 Reliability Cantered Maintenance ................................................................................... 12
3.2.3 Gas Cutting .................................................................................................................... 12
3.2.4 Peddiworker No.1........................................................................................................... 13

6. v
Chapter-4: Quality .......................................................................................................................... 18
4.1 Quality Plan .......................................................................................................................... 18
4.2 Quality Assurance ................................................................................................................. 18
4.2.1 Personal Qualification .................................................................................................... 19
4.2.2 Test Equipment and Procedure ....................................................................................... 19
4.2.3 Monitoring of NDT Processes ........................................................................................ 19
4.2.4 Test Procedure................................................................................................................ 19
4.2.5 Environmental Conditions .............................................................................................. 19
4.3 Quality Testing...................................................................................................................... 19
4.4 Welding Quality.................................................................................................................... 20
4.4.1 Liquid Penetrant Test(LPT)/ Dye Penetrant Test............................................................. 20
4.4.2 Ultrasonic Testing .......................................................................................................... 22
4.4.3 Magnetic Particle Test .................................................................................................... 24
4.4.4 Radiographic Testing (RT) ............................................................................................. 25
Chapter-5: Human Resource and Project Management.................................................................... 27
5.1 Manpower Working at NHE.................................................................................................. 27
5.2 Project Management.............................................................................................................. 27
5.3 Stages of Project.................................................................................................................... 28
5.3.1 Cost Estimation and Bidding .......................................................................................... 28
5.3.2 Contract Agreement........................................................................................................ 28
5.3.3 Manpower Requirement ................................................................................................. 28
5.3.4 Design............................................................................................................................ 29
5.3.5 Procurement ................................................................................................................... 29
5.3.6 Fabrication ..................................................................................................................... 29
5.3.7 Transportation ................................................................................................................ 29
5.3.8 Erection and Commissioning .......................................................................................... 29
Chapter-6: Welding......................................................................................................................... 30
6.1 Types of Welding.................................................................................................................. 30
6.1.1 Metal Inert Gas (MIG) Welding...................................................................................... 30
6.1.2 Tungsten Inert Gas (TIG) Welding ................................................................................. 31
6.1.3 Submerged Arc Welding( SAW) ................................................................................... 32
6.1.4 Arc Welding................................................................................................................... 32
6.2 Welding Techniques in NHE................................................................................................. 34

7. vi
6.2.1 Metal Inert Gas (MIG) Welding...................................................................................... 34
6.2.2 Tungsten Inert Gas ......................................................................................................... 34
6.2.3 Submerged Welding ....................................................................................................... 35
6.2.4 Arc Welding................................................................................................................... 35
6.3 Welding Codes and Standards ............................................................................................... 35
6.3.1 Welding Thin Metals...................................................................................................... 36
6.3.2 Welding Medium Thickness Metals................................................................................ 36
6.3.3 Welding Thick Metals .................................................................................................... 37
6.3.4 Types of Electrode.......................................................................................................... 38
6.3.5 Types of Metals Used in NHE ........................................................................................ 52
Chapter-7: Gates............................................................................................................................. 55
7.1 Different Types of Gates ....................................................................................................... 55
7.1.1 Vertical Gates................................................................................................................. 55
7.1.2 Radial/Tainter Gates....................................................................................................... 57
7.2 Working Mechanism of Gate................................................................................................. 58
7.3 Applications of Gate.............................................................................................................. 58
Chapter-8: Grinding........................................................................................................................ 59
5.1 Grinding Principle and Working Mechanism......................................................................... 59
8.2 Grinding or Abrasive Wheel.................................................................................................. 59
8.3 Types of Grinding Process .................................................................................................... 60
8.3.1 Wet Grinding Process..................................................................................................... 60
8.3.2 Dry Grinding Process ..................................................................................................... 60
8.4 Types of Grinding Machine................................................................................................... 60
8.4.1 Electrically Powered........................................................................................................... 60
8.4.2 Pneumatic Powered Grinder ........................................................................................... 61
8.4.3 Types of Portable Grinder:.............................................................................................. 61
8.4.4 Types of Grinding Wheels.............................................................................................. 62
8.4.5 Reading a Grinding Wheel’s Specification...................................................................... 64
CHAPTER-9: TURBINE................................................................................................................ 65
9.1 Classification of Turbines...................................................................................................... 65
9.1.1 Depending Upon the Nature of Interaction with Water Flow........................................... 65
9.1.2 Depending Upon the Nature of Flow in the Machine ...................................................... 65
9.1.3 Depending Upon the Head.............................................................................................. 66

8. vii
9.1.4 Depending Upon the Specific Speed............................................................................... 66
9.2 Efficiencies of Turbines ........................................................................................................ 66
9.2.1 Volumetric Efficiency (ηV)............................................................................................. 66
9.2.2 Hydraulic Efficiency (ηh)................................................................................................ 66
9.2.3 Mechanical Efficiency (ηm) ............................................................................................ 67
9.2.4 Overall Efficiency (ηo).................................................................................................... 67
9.3 Specific Speed....................................................................................................................... 67
9.4 Francis Turbine ..................................................................................................................... 68
9.4.1 Components of Francis Turbine...................................................................................... 69
9.4.2 Efficiency....................................................................................................................... 71
9.4.3 Cavitation in Francis Turbine ......................................................................................... 72
9.4.4 Repair of Cavitation Damage.......................................................................................... 72
9.4.5 Types of Draft Tube ....................................................................................................... 73
9.5 Pelton Turbine....................................................................................................................... 75
9.5.1 Components of Pelton Turbine ....................................................................................... 76
9.5.2 Working Proportion of Pelton Turbine............................................................................ 79
9.5.3 Governing in Pelton Turbine........................................................................................... 80
9.5.4 Cavitation in Pelton Turbine........................................................................................... 80
9.6 Comparison of Pelton and Francis Turbine............................................................................ 81
9.7 Balancing of Turbine............................................................................................................. 81
9.7.1 Static Balancing ................................................................................................................. 81
9.7.2 Dynamic Balancing ............................................................................................................ 82
9.7.3 Differences between Static and Dynamic Balancing ........................................................... 82
CHAPTER-10: ELECTRICAL DIVISION..................................................................................... 83
10.1 Failure of a Transformer...................................................................................................... 83
10.2 List of Machines.................................................................................................................. 83
10.3 Major Task of Electrical Department ............................................................................... 83
10.3.1 Tapping ........................................................................................................................ 83
10.3.2 Testing ......................................................................................................................... 84
10.3.3 Winding........................................................................................................................ 84
10.4 Transformer Oil Purification ............................................................................................... 84
References ...................................................................................................................................... 86

9. viii
LIST OF ABBREVIATIONS
AC = Alternating Current
AWS = American Welding Society
DC= Direct Current
DCEN = Direct Current Electrode Negative
DCEP = Direct Current Electrode Positive
DPT = Dye Penetration Testing
FCAW = Flux- Cored Arc Welding
GMAW = Gas Metal Arc Welding
GTAW= Gas Tungsten Arc Welding
HAZ = Heat Affected Zone
HMW = Heavy Mechanical Workshop
HRM = Human Resource Management
KVA = Kilo Volt Ampere
LPG= Liquid Petroleum Gas
MIG = Metal Inert gas
MPT= Magnetic Particle Testing
MVA = Mega Volt Ampere
MW = Mechanical Workshop
NDT = Non-Destructive Testing
NHE = Nepal Hydro and Electric Limited
PSI = Pound to square Inch
QA = Quality Assurance
QC = Quality Certificate
SMAW = Shield Metal Arc Welding
SMAW = Sub- Merged Arc Welding
TIG= Tungsten Inert Gas Welding
UT = Ultrasonic Testing

10. ix
LIST OF FIGURES
Figure 1: Organizational Structure of NHE .......................................................................................2
Figure 2: Safety Posters of NHE .......................................................................................................8
Figure 3: Gas Cutting...................................................................................................................... 12
Figure 4: Peddiworker No. 1 ........................................................................................................... 13
Figure 5: Control System ................................................................................................................ 14
Figure 6: Foot Switch...................................................................................................................... 16
Figure 7: Machine Workstation....................................................................................................... 16
Figure 8:Peddiworker No 1 Machine Specifications........................................................................ 17
Figure 9: NDT Chemical and Result ............................................................................................... 20
Figure 10: UT Principle and Operation............................................................................................ 23
Figure 11: Various Form of Result During UT ................................................................................ 24
Figure 12: Basic Principle of MPT.................................................................................................. 24
Figure 13: Manpower Working at NHE .......................................................................................... 27
Figure 14: MIG Welding Schematic................................................................................................ 31
Figure 15: TIG Welding Schematic................................................................................................. 31
Figure 16: Submerged Arc Welding................................................................................................ 32
Figure 17: Electrode Specification and Arc Welding....................................................................... 33
Figure 18: MIG Welding Setup...................................................................................................... 34
Figure 19: TIG Welding Setup........................................................................................................ 34
Figure 20: Slag from Submerged Welding ...................................................................................... 35
Figure 21: Most Common Electrode Used in NHE.......................................................................... 35
Figure 22:Variation of Beads Form on Different Conditions .......................................................... 37
Figure 23: Different Joints for Different Thickness of Metal ........................................................... 37
Figure 24: Vertical Gates ................................................................................................................ 55
Figure 25: Reference Material and IS Number for Vertical Gate ..................................................... 56
Figure 26: Radial Gate.................................................................................................................... 57
Figure 27: Bench Grinder with Grinding Wheel.............................................................................. 60
Figure 28: Portable Grinder and Grinding Wheel ............................................................................ 61
Figure 29: Pneumatic Angled Grinder............................................................................................. 61
Figure 30: Different Sized Angle Grinder ....................................................................................... 62
Figure 31: Tool Post Grinder........................................................................................................... 62
Figure 32: Straight Resinoid Grinding Wheel.................................................................................. 63
Figure 33: Spindle Mounted Points Grinders................................................................................... 63
Figure 34: Spindle Mounted Flap Wheels ....................................................................................... 63
Figure 35: Flap Wings Grinding Wheel........................................................................................... 64
Figure 36: Grinding Wheel’s Specification ..................................................................................... 64
Figure 37: Losses and Efficiency of Turbine ................................................................................... 67
Figure 38: Schematic Diagram of Francis Turbine .......................................................................... 69
Figure 39: Francis Turbine Runner Schematic Sketch ..................................................................... 71
Figure 40: Cavitation in Francis Blade and Guide Vane .................................................................. 72
Figure 41: Repairing Francis Runner............................................................................................... 73
Figure 42:Vertical-type Draft Tube................................................................................................. 74

11. x
Figure 43: Simple Elbow-type Draft Tube....................................................................................... 74
Figure 44: Elbow-type Draft Tube of Varying Cross-section........................................................... 75
Figure 45: Moody’s Spreading / Hydrocone Draft Tube.................................................................. 75
Figure 46: Pelton Wheel and Bucket ............................................................................................... 77
Figure 47: Basic Dimensions of Pelton Bucket................................................................................ 77
Figure 48: Nozzle Assembly of Pelton Turbine ............................................................................... 79
Figure 49: Tapping in a Transformer............................................................................................... 83
Figure 50: Equipment in Electrical Division.................................................................................... 85

12. xi
LIST OF TABLES
Table 1: Parts of Peddiworker No.1................................................................................................. 14
Table 2: Control System.................................................................................................................. 15
Table 3: Switching Position of Foot Switch..................................................................................... 15
Table 4: Symbol for Different Job Operation .................................................................................. 16
Table 5: Peddiworker No.1 Specification ........................................................................................ 17
Table 6: Chemical Composition of E 6013...................................................................................... 39
Table 7: Mechanical Properties of Deposited Metal of E 6013 ........................................................ 39
Table 8: Chemical Composition of 13/4 .......................................................................................... 40
Table 9: Mechanical Properties of Deposited Metal of 13/4 ............................................................ 40
Table 10: Chemical Composition of 13/04 Si.................................................................................. 41
Table 11: Mechanical Properties of Deposited Metal of 13/04 Si .................................................... 41
Table 12: Chemical Composition of ER 70S-6................................................................................ 42
Table 13: Mechanical Properties of Deposited Metal of ER 70S-6 .................................................. 42
Table 14: Chemical Composition of 308 L Si.................................................................................. 43
Table 15: Mechanical Properties of Deposited Metal of 308 L Si .................................................... 43
Table 16: Chemical Composition of E 7018.................................................................................... 44
Table 17: Mechanical Properties of Deposited Metal of E 7018 ...................................................... 44
Table 18: Chemical Composition of E410 NiM0-26........................................................................ 44
Table 19: Mechanical Properties of Deposited Metal of E410 NiMo-26......................................... 45
Table 20: Chemical Composition of 16/6 M-HD............................................................................. 45
Table 21: Mechanical Properties of Deposited Metal of 16/6 M-HD ............................................... 46
Table 22: Chemical Composition of 95-S........................................................................................ 46
Table 23: Mechanical Properties of Deposited Metal of 95-S ......................................................... 47
Table 24: Chemical Composition of E 9018................................................................................... 47
Table 25: Mechanical Properties of Deposited Metal of E9018 ...................................................... 47
Table 26: Chemical Composition of 23/12-16................................................................................. 48
Table 27: Mechanical Properties of Deposited Metal of 23/12-16................................................... 48
Table 28:Comparision Table of Different Electrodes Available in NHE......................................... 49
Table 29: Most Used Electrodes for Welding SS in NHE................................................................ 50
Table 30: Most Used Electrodes for Welding MS in NHE............................................................... 51
Table 31: Chemical Composition of Mid Steel Sheets of Grade 250, 350, and 450......................... 52
Table 32: Mechanical Properties of Mid Steel Sheets of Grade 250, 350 and 450............................ 52
Table 33: Mechanical Property of A240 Stainless Steel Plate.......................................................... 53
Table 34: Chemical Composition of A240 Stainless Steel Plate ...................................................... 53
Table 35: Chemical Composition of SS 202 Plate ........................................................................... 54
Table 36: Mechanical Properties of SS 202 Plate ........................................................................... 54
Table 37: Components of Gate........................................................................................................ 58
Table 38: Grinding Wheel Specifications ........................................................................................ 60
Table 39: Specific Speeds of Different Kinds of Turbines ............................................................... 66
Table 40: Variables Affecting Performance of a Turbine................................................................. 68
Table 41: Working Proportion of Pelton Turbine ............................................................................ 79
Table 42: Comparison of Pelton and Francis Turbine ...................................................................... 81

13. xii
Table 43: Differences between Static and Dynamic Balancing ........................................................ 82
Table 44: List of Machines in Electrical Division............................................................................ 83

14. 1
CHAPTER-1: INTRODUCTION
1.1 Background of NHE
NHE is a public limited company, which was established in BS 2042 (AD 1985). It is a subsidiary of
Butwal Power Company Limited in partnership with IKN Industrial AS Norway, Butwal Technical
Institute and Himal Hydro and General Construction Limited. The company has been implementing
well- structured Quality Management system since 2002 AD. It is an ISO 9001:2008 certified
company. NHE’s area of expertise includes design, manufacture and installation of equipment of
electricity generation (from Hydro Power), transmission and distribution.
Nepal Hydro & Electric Limited (NHE) is a leading Company in Hydro-mechanical and Electro-
mechanical equipment including HV substations, manufacturing and installation & repair for hydro
& electric power sector, where 250+ employees are working together as a team. Its main market is
equipment for electricity generation (from hydropower), transmission and distribution. In addition,
the company has significant involvement in manufacture of heavy steel structures and many other
areas. Numerous combinations of design, manufacture and installation can be carried out including
project management to customer requirements.
NHE rightly takes pride in the quality of work performed. Its quality department is considered by
most of the clients as the best one in the country. Within the team of highly talented engineers and
highly skilled technicians, NHE is capable of executing challenging projects which has helped the
organization grow into one of the leading public company in Nepal. As an ISO certified everything is
done within a system. To perform each task systematically and scientifically, different division and
made assigning task to each division which has made the work easy to accomplish.
The Different sections of NHE are divided into the following divisions:
i. Human Resource Division
ii. Service Division
 Turbine Section
 Repair and Maintenance
iii. Quality Division
iv. Finance Division
 Store Section
 Costing Section
v. Mechanical Division
 Heavy Machinery Workshop (HMW)
 Mechanical Workshop (MNW)
 Mechanical Design
vi. Electrical Division
1.2 Company Objectives
 Growth
To ensure a steady growth by enhancing the competitive edge of NHE in existing business,
news area and International Operation, so as to fulfill the national exceptions from NHE.
 Profitability
To provide a reasonable and adequate return on capital employed, primarily, through
improvement in operational efficiency, capacity utilization and productivity, and generate
internal resources to finance the company’s growth.
 Customer Focus
To build a high degree of customer confidence by increasing value for his money through
international standard of product quality, performances and superior services.

15. 2
 People – Orientation
To enable each employee to achieve his potential, improve his capabilities, perceive his role
and responsibilities participate and contributed positively to the growth and success of the
company. To invest in human resources continuously and be alive to their needs.
1.3 Capabilities of NHE
i. Hydro-mechanical equipment
 Steel Liners, Penstock Pipes and Manifold (max. 8m Dia.), Bifurcation/Trifurcation
 Hydraulic Gates (Radial, Roller, Slide & Flap) max. 24 m x 22 m
 Stop logs and Trash racks
ii. Electro-mechanical equipment
 Manufacturing of Francis Turbine Stay Ring, Spiral Casing and Draft Tube
 Manufacturing of Pelton Turbine Housing and components
 Installation and testing of complete Electro-mechanical Equipment
iii. High Voltage Substation construction (Turn Key Project)
iv. Manufacturing/Repairing of high Voltage Generator/Motor Coil for up to 50 MW unit
Generator and Motor Coil Workshop
v. Reclamation of Turbine Runner up to 4.5m Dia.
vi. Repairing of Power Transformer and Distribution Transformer. Detail of Transformer Plant
vii. Design, Manufacturing and Installation of heavy steel structures (motorable bridges,
transmission towers etc.)
1.4 Mission and Vision
To satisfy customer needs in the manufacture, erection, testing, commissioning and through life
support of equipment in the hydroelectric power generation, transmission and distribution industry,
by building up our own capabilities and by maximizing the use of local resources. Our vision is to be
Nepal’s leading manufacturer and refurbisher of hydro and electric power equipment. We will be
competent in all areas of this work and apply our competence to other markets whenever possible.
We will maintain a high standard in our services and provide high quality products, manufactured
locally whenever practicable.
1.5 Organizational Structure
Figure 1: Organizational Structure of NHE
(NHE, 2014)

16. 3
CHAPTER-2: Hydroelectric Power Plant
2.1 Types of Hydroelectric Plant
2.1.1 Based on Power Generation
a) Pico hydropower
Hydroelectric plant that can generate power up to 5 KW .
b) Micro hydropower
Hydroelectric plant that can generate power from 5 KW to 100 KW .
c) Mini hydropower
Hydroelectric plant that can generate power from 100 KW to 1 MW.
d) Small hydropower
Hydroelectric plant that can generate power from 1 MW to 15 MW.
e) Medium hydropower
Hydroelectric plant that can generate power from 15 MW to 100 MW.
f) Large hydropower
Hydroelectric plant that can generate power above 100 MW.
2.1.2 Based on Storage
i. Run of river without pondage
ii. Run of river with pondage
iii. Reservoir
iv. Pumped storage
2.1.3 Based on Head Available
a) Low head
Hydropower having a head less than 25 meters.
b) Medium head
Hydropower having head between 25 m to 100 m.
c) High head
Hydropower having head above 100 m.
2.2 Essential Components
The essential components of hydroelectric power plants are
a) Intake structure
These structures include booms, screens or trash racks, sluices to divert and prevent entry of
debris and ice into the turbines.
b) Forebay
A forebay is an enlarged body of water just above the intake to store water temporarily to meet
the load fluctuations

17. 4
c) Spillway
It is considered as a safety valve. It discharges the overflow water to the down-stream side when
the reservoir is full mainly during flood periods.
d) Penstock
It is a closed conduit which connects the fore bay or surge tank to the scroll case of the
turbine. In long penstocks great care must be taken to protect the pipe against water hammer.
Generally, they are made of steel. The thickness must be sufficient enough to withstand both the
normal hydrostatic pressure and also the sudden pressure fluctuation both above and below
normal caused by fluctuations in load and by emergency conditions.
The components of penstock pipes are expansion joints, anchor block, drain valve, breed valve,
and support pillars.
e) Surge Tank
A small storage reservoir or tank (open at the top) for receiving the rejected flow and thus
relieving the pipe of excessive water hammer pressure. An increased pressure in the penstock due
to reduction in load on the generator which causes the governor to close the turbine gates is water
hammering effect.
f) Valves and Gates
These are needed to shut off the flow and provide for unwatering the turbine for inspection and
repairs. Gates are usually of two types vertical and radical whereas commonly used valves are
butterfly valve and pivot type valve.
g) Trash Rack
They are installed at the intake point that helps to prevent wooden logs, fishes, large sediments or
any other floating objects entering into penstock and protect the turbines from being damaged.
h) Tailrace
It is used to discharge water after useful energy is extracted with the help of a turbine into the
same stream or to another one. The design and size of the tailrace should be such that water has a
free exit after it leaves the turbine.
i) Draft Tube
Draft tube has its increasing section from runner exit to the tailrace. Kinetic energy possessed by
the water leaving the runner outlet is converted into pressure energy and the water leaves at the
tailrace at a much reduced velocity.
j) Turbine
It is the main mechanical component of hydropower which converts hydraulic energy of water
into mechanical and to electrical energy with the help of alternator. In Nepal mainly used
turbines are pelton and francis.
2.3 Safety Engineering
Safety engineering is the process of designing workplaces to prevent accidents. Engineering Safety
concepts provide detailed approaches and modes for accident reduction by using a risk management
process to identify and "design out" hazards.
Accidents can and do happen. Workplaces and factories which use machinery, chemicals, and other
potentially hazardous elements, are always possible sites for accidents which may cause injury, or
even death if a comprehensive engineering safety approach is not taken.

18. 5
Safety engineering also is the key component for eliminating hazards that would otherwise be
controlled by either administrative controls or use of personal protective equipment as a barrier
between a hazard and a worker. These engineered safeguards include machine guards, selection of
less hazardous equipment, development of maintenance schedules to ensure equipment safety, and
inspection procedures, selection of safer tools, safety review of new equipment, employee
maintenance training, safe design of the flow of material and people through a facility and risk
analysis for both possible man-made and natural incidents.
2.3.1 Effects of Non-ionizing Electromagnetic Fields on Human Body
Non-ionizing radiation is described as any type of electromagnetic radiation that does not carry
enough energy to ionize atoms or molecules to completely remove an electron from an atom or
molecule. Non-ionizing radiation simply heats the substances.
We are exposed to low levels of non-ionizing radiation everyday exposure to intense and direct
amounts of non-ionizing radiation may result in damage to tissue due to heat.
Examples: radio frequency radiation used in broadcast and communication, microwave, infrared
radiation used in heat lamps, furnaces and boilers in workshops etc.
2.3.2 Physical Effects of Electric Shocks
Electricity is defined as flow of electrical power or charge. When we come in contact with an electric
current we receive a shock. It may arise due to flowing current or static charge. common sources of
getting shocks are
 Electric wall outlets
 Faulty appliances
 Power line
 Lightening
 Damaged cords
The effects of electric shocks are classified as long term and short term.
2.3.2.1 Short Term Effects
 Burns
If a high voltage electrical injury occurs, the shock will cause burns ranging from first degree
to fourth degree.
 Traumatic injuries
Injuries such as spinal or cranial might occur if the electric shock is powerful enough to
throw a person physically or if the shock happens at a great height.
 Amputation
When the shock causes a burn of fourth degree amputation may be necessary. Fourth-degree
burns affect the skin, tissues, vessels and muscles and bone.
2.3.2.2 Long Term Effects
 Physical effects:
 Eye problems, specifically the rapid development of cataracts
 Generalized pain that many don’t receive satisfactory relief from
 Ghost pains or itches, specifically in those suffering from amputations
 Joint stiffness, arthritis and contracture due to muscle damage
 Muscle pain and spasms
 Permanent neurological injuries such as paralysis
 Itching, possibly as a side effect of the burns

19. 6
 Psychological effects:
 Reduced cognitive abilities, specifically verbal recall and attention span
 Post-traumatic stress disorder (PTSD)
 Anxiety
 Depression
 Development of a phobia
 Memory loss, especially around incident and recovery
 Neurological effects:
 Numbness, tingling or pins and needles sensation (parenthesis) due to nerve damage
 Carpal tunnel syndrome due to median nerve damage
 Paralysis
 Seizure disorders
 Dizziness, loss of balance or fainting spell
 Migraine
2.3.3 Safety and Precautions
Safety and precautions are the activities that seek either to minimize or to eliminate hazardous
conditions that can cause bodily injury. These measures include wearing protective gear such as
gloves and eye protection, using equipment that is in good repair, and cleaning up spills. Safety
precautions are essential in workplaces and other environments where people may be exposed to
hazards. They can help prevent accidents and injuries, and they can also help protect people from
long-term health problems caused by exposure to hazardous materials or conditions.
2.3.3.1 Tools and Machinery Safety
 Use machinery only if you’re authorized, trained, and alert.
 Always use the appropriate tool for the respective task.
 Clean your tools and keep them in good working order.
 Organize your tools and don’t be careless; someone could easily slip or get hit due to a
misplaced object.
 Do not perform a task unless you’ve been trained and you are aware of the hazards as well as
how to mitigate/eliminate them.
 Never leave machinery running unattended.
 Never remove safety guards that are in place to protect you and the surrounding area.
 Obey all operating instructions.
 If something is wrong, stop the machine immediately and get assistance.
 Communicate your location and process to those around you, so they’ll know where you are,
what you’re doing, and when they need to be getting out of the way.
 Always read labels and instructions alerting you to potential dangers and hazards.
 Unless it’s your job, never tamper with electric controls, cords, switches, or other such
hazardous items.
 Dress properly and compactly: loose, or hanging clothes and accessories (ties, earrings,
bracelets, loose sleeves, etc.) may easily get caught up in moving parts.
 Turn off machines and equipment before you even consider cleaning, un-jamming, oiling,
adjusting, or moving them.
2.3.3.2 Safety Against Fire Hazards
 Fire extinguishers must be available and readily attainable.
 Practice fire drills.
 Avoid “power strips” which can ignite a fire if overloaded.
 Ventilation is critical, especially if dealing with fumes and chemicals.

20. 7
 Good ventilation helps to reduce the toxins in the air, and thus to eliminate highly flammable
vapors.
 In case of fire, know what has fed the fire.
 Never fight a grease fire with water; water will splash the oil and spread the flames.
 Be aware of the whereabouts and use of fire extinguishers.
2.3.3.3 Gearing Safety
 Always wear appropriate clothing and non-skidding shoes respective to your job.
 First aid kits must be available and readily attainable.
 A hard hat will protect you if there’s a risk of falling objects
 Wear gloves if you’re handling sharp objects or toxic substances.
 Wear goggles if your work poses a hazard to your eyes.
 Wear safety harnesses if you’re working from an elevated location and there’s the risk of
falling.
 Wear a breathing mask at all times.
2.3.3.4 Safety Against Noise Hazard
 Change or modify equipment producing loud noise.
 Lubricate the mating parts of the machine.
 Locate the equipment in a more isolated area, or soundproof the room.
 Make sure that people spend time working in quiet areas too.
 Try to run noisy equipment early or late in the day when fewer people will be exposed.
 Use personal hearing protection such as ear plugs or ear muffs.
2.3.3.5 Safety and Precautions in NHE
 Check if all the machine components are at their proper conditions before operating a
machine
 Check if the electricity is supplied properly.
 Start the work after checking all the required tools, grinding wheels, drill bits, etc. has proper
edge.
 Use the safety equipment such as goggles during grinding, chips cutting, gloves, boots/shoes,
apron/dress, masks etc. according to working conditions.
 Do not pile up the objects or work pieces around the machines.
 Always keep the machine working space clean.
 Chips, dirt, metal pieces, and remaining welding electrodes should be managed properly.
 Nuts and bolts used in the machine should be checked regularly before operating them.
 Lubricate the machine and tools from time to time.
 Concentrate on your work without any distraction of surroundings.
 Health and safety meetings are conducted to check any missing safety measures and
implement new measures.
2.3.3.6 Safety Tools and Equipment Available in NHE
 NHE is one of the companies having ISO certified for safety of workers and working
environment. The equipment and tools available in NHE are:
 Fire Extinguisher
 First aid box for post accidents
 Apron, Leather Boots, Google, Leather Gloves, Rubber Gloves, Breathable Mask
 Lead walls for protection from radiation

21. 8
 Rubber padded walls in sand blast compartment to protect impact on concrete structure
 Metallic helmets with oxygen mask to protect from sand impact and hazardous fumes
 Manual emergency control system for sudden electric hazards.
 Proper ventilation and lightning in workshops
 Open space in case of emergency rush
 Proper cooling system using fans to protect from non-ionizing radiations
 Proper manuals and guidelines of machineries
 Posters having safety rules are mounted on the walls according to the nature of the
 workshops.
Figure 2: Safety Posters of NHE

22. 9
Chapter-3: Service Division
3.1 Turbine Section
Turbine section mainly deals with the repair, maintenances, testing, and commissioning of turbine
runners, guide vane, shaft, and hydraulic pump.
 Turbine:
Turbine is a rotary mechanical device that extracts energy from a fluid flow and converts into
useful work. The work produce by turbine can be used for generating electrical power when
combined with a generator.
 Runner:
In hydraulic turbines, the blades are also called as a runners which rotates when the fluid flows in
the casing and comes in contact with it. While shaft is connecting medium between the blades
and the generator which rotates when the blade is in motion thus in turn producing electricity.
 Guide Vane:
The guide vanes consist of number of blades that can be adjusted in order to increase or reduce
the flow rate through the turbine. The vanes are arranged between two parallel covers normal to
the turbine shaft.
 Hydraulic Pump:
The mechanical device that is used to convert mechanical power into hydraulic energy is known
as a hydraulic pump. The load that is responsible for the pressure is overcome with this device by
creating sufficient power and generating a flow. The hydraulic pump has two functions to
perform during operation, allowing atmospheric pressure to push liquid into the inlet line from
the reservoir to the pump by the mechanical action created vacuum at the pump. The other
function it performs is that the pumps mechanical action supplies the liquid to the pump outlet
and then forced into the hydraulic system.
Hydro Mechanical Structures that can be repaired at NHE are Listed below:
 Pelton Turbine
 Pelton bucket
 Turbine shaft
 Nozzle
 Francis Turbine
 Francis runner blade
 Guide Vane
 Head Cover
 Bottom Ring
 Side cover
3.1.1 Process for Repairing
i. First of all, part to be repaired is brought to the service section then, job no. is assigned to it
and the time of completion is evaluated and repairing works starts.
ii. The repairing process include
 Pre-heating and Welding

23. 10
 Machining profile grinding
 Heat treatment and balancing (static)
iii. Different testing
 DPT (Dye Penetration Test)
 MPT (Magnetic Particle Testing)
 X- ray & Ultrasound test
iv. Testing and commissioning
3.1.2 Repair Methods
3.1.2.1 Weld Repair
Welding is the most common and to date, the most successful method of repairing cavitation damage
on hydraulic turbines. The various steps for repair by welding are as follows:
i. Initial dimensional checks
ii. Application of braces of strong backs Surface preparation
iii. Preheat
iv. Weld inspection
v. Grinding to contour
vi. Weld inspection
vii. Removal of braces and strong backs Final dimensional checks
In addition, prior to the start of weld repairs, the following must be established:
 Composition of base material
 Weld material, weld process and repair procedure
3.1.2.2 Safety Considerations
As with other types of maintenance work, safety considerations must not be overlooked. The
maintenance platform under the runner must be adequately designed for the equipment and personnel
loads to be handled during the repair program. Ventilation during welding is important. Gates and
main doors should be open and exhaust fans should be available for removal of smoke and fumes.
Proper and adequate lighting of high intensity should be provided. If weld procedure incorporates
high pre- or post-heat, insulated blankets are necessary to protect the personnel.
3.1.2.3 Composition of Base Material
When planning cavitation repairs, it is important to know the chemistry of the base material. For
newer units, the ASTM specification is usually known. The exact composition may also be available
from tests records. If the composition of the material is not known, a chemical analysis should be
made from a small sample of the runner or component being repaired.
3.1.2.4 Weld Materials
Areas where the depth of weld after surface preparation is greater than 3/8-inch (10 mm) should be
built up to 3/8-inch (10 mm) depth with E7018 mild steel weld material. Stainless steel material
should not be used in areas of deep cavitation because of the increased possibility of blade distortion

24. 11
resulting from the difference in coefficient of thermal expansion between the stainless and carbon
steel.
3.1.2.5 Weld Process
Three processes are used for cavitation repair welds:
i. Metal Inert Gas (MIG) Welding
ii. Tungsten Inert Gas (TIG) welding
iii. Arc Welding
3.1.2.6 Repair Procedure
The procedures developed for cavitation repairs are site specific because of the many factors
involved. It is recommended that procedures be established for each repair program to maintain a
consistent approach, to monitor the results and to avoid excessive costs in any one area of the
program. These procedures should be modified to incorporate any changes which could benefit
subsequent repairs. The items discussed below illustrate some of the important points which should
be covered by the procedures.
i. Initial dimensional checks
ii. Francis runners vent opening
iii. Preheating
iv. Final dimensional checks
3.2 Service and Maintenance
This document is intended to establish recommended practice as well as to give general advice and
guidance in the maintenance of mechanical equipment owned and operated by Nepal Hydro and
Electric Limited. Maintenance recommendations are based on industry standards and experience in
Reclamation facilities. However, equipment and situations vary greatly, and sound engineering and
management judgment must be exercised when applying these recommendations. Other sources of
information must be consulted (e.g., manufacturer’s recommendations, unusual operating conditions,
personal experience with the equipment, etc.) in conjunction with these maintenance
recommendations.
3.2.1 Preventive Maintenance
Preventive maintenance (PM) is the practice of maintaining equipment on a regular schedule based
on elapsed time or meter readings. The intent of PM is to “prevent” maintenance problems or failures
before they take place by following routine and comprehensive maintenance procedures. The goal is
to achieve fewer, shorter, and more predictable outages.
Some advantages of PM are:
It is predictable, making budgeting, planning, and resource leveling possible.
When properly practiced, it generally prevents most major problems, thus reducing reactive
maintenance, and maintenance costs in general.
It assures managers that equipment is being maintained.

25. 12
It is easily understood and justified.
PM does have some drawbacks:
 It is time consuming and resource intensive.
 It does not consider actual equipment condition when scheduling or performing the
maintenance.
 Despite these drawbacks, PM has proven generally reliable in the past and is still the core of
most maintenance programs.
3.2.2 Reliability Cantered Maintenance
RCM programs are gaining in popularity and have been piloted in a few Reclamation power facilities
with good results. The goal of these programs is to provide the appropriate amount of maintenance at
the right time to prevent forced outages while at the same time eliminating unnecessary maintenance.
Implemented properly, RCM can eliminate some of the drawbacks of PM and may result in a more
streamlined, efficient maintenance program. RCM seems very attractive in times of diminishing
funding, scarcity of skilled maintenance staff, and the pressure to “stay online” due to electric utility
industry deregulation.
3.2.3 Gas Cutting
Gas welding is a welding process that melts
and joins metals by heating them with a flame
caused by a reaction of fuel gas and oxygen.
The most commonly used method is
oxyacetylene welding due to its high flame
temperature. The flux may be used to
deoxidize and cleanse the weld metal. The
flux melts, solidifies and forms a slag skin on
the resultant weld metal.
In NHE LPG is used instead of acetylene gas
because it is economical and efficient for
cutting metals. LPG when combined with
oxygen produces a slightly lower flame
temperature than acetylene, up to a maximum
of 2810 ºC. The oxy/LPG is used mainly for
cutting the mild steel structure such as large
cylinders, thick plates. LPG regulators have
only a delivery pressure gauge. The reason is
that LPG is a liquid in the cylinder so is at
constant pressure until the cylinder is empty.
The oxy / LPG mixture uses more oxygen in
its ratio (4.3:1) the flame will have a bluish
highly oxidizing appearance. But it is not as
oxidizing as it may appear when compared
with an acetylene flame.
The gas used is whether acetylene or LPG can
be determined by looking at the hose pipe
color and the torch tip. The acetylene hose is
of red color and that of the LPG is orange in
color. The acetylene torch tip releases a high
amount of heat because it has sharp and
focused flame.
Figure 3: Gas Cutting

26. 13
3.2.4 Peddiworker No.1
The Peddiworker No. 1 is a product belonging to the Peddinghaus Machine Tool Product Group.
Series design, years of experience in machine tool building coupled with modern production and
testing methods guarantee a high standard of quality together with reliable operation and long service
life.
It is a hydraulically powered universal steel worker equipped with a flat bar, section and bar stock
shearing station, a notcher/ coper and a punching unit. The machine is a high grade production
equipment of robust design and particularly maintenance friendly.
3.1.2.1 Brief Description and Machine Function
Figure 4: Peddiworker No. 1

27. 14
The machine consists of following main assemblies:
Table 1: Parts of Peddiworker No.1
Item Description
A Flat bar, section and bar stock shearing station with hold-down
B Punch unit with push-away stripper, quick-change punching attachment and support
table
C Notcher / coper with support table
D Switch cabinet with controls
E Foot switch
F Safety guard on the punch unit / notcher/coper / flat bar, section and bar stock shearing
station.
G Hydraulic power-pack with pressure gauge
3.1.2.2 Control and displays on the machine
Figure 5: Control System

28. 15
Table 2: Control System
No Description Function
1 Main switch 0= power off
1= power on
2 Mode of operation Set up mode and punching mode
3 Button with indicator lamp(on state) Machine functions are switched on indicated
by white light
4 Button (off state) Machine function are turned off
5 Workstation selector Cutting via contact length stop, cutting and
notching
6 Socket External contact length to prevent shear
station
7 Pressure Gauge Show generated hydraulic pressure
3.1.2.3 Foot Switch
The foot switch has two switching positions:
Table 3: Switching Position of Foot Switch
Position Mode of operation Action, operator Machine function
0
● Off
Foot pedal not operated Tools are in the upper position
1
● Punching
● Cutting
● Notching
Operate foot pedal Work piece is punched, notched or cut

29. 16
Figure 6: Foot Switch
3.1.2.4 Machine Workstation
The machine can be used for 5 different purposes:
Table 4: Symbol for Different Job Operation
SN Symbol Description
1 Punch unit
2 Notcher
3 Flat bar shear
4 Bar stock shear
5 Section stock shear
Figure 7: Machine Workstation

30. 17
3.1.2.5 Machine Specifications
Table 5: Peddiworker No.1 Specification
Specification Units Values
Rated capacity kW 4
Operational pressure bar 250
Oil operating temperature max. ℃ 80
Charge of hydraulic fluid L 45
Noise level dB ≤70
Max. rated capacity at a material tensile strength N/mm² 450
Figure 8:Peddiworker No 1 Machine Specifications

31. 18
Chapter-4: Quality
Quality Assurance and Quality Control is applicable in construction, production and servicing
industries. Mechanical, civil, electrical, electronics, instrumentation, production, automobile
and even other engineering branches also has QA/QC programs according to their
requirement. Usually qualified and well experienced persons are working in quality control
department of engineering companies. There for quality check comes to be the most
important activity after the manufacturing or after the companies of repair and maintenance.
The quality department of NHE deals with setting standards and having an effective
mechanism for checking whether the standards are met and also having a corrective system if
necessary. The tasks carried by this section indispensable given that it is one which make
goods or services provided dependable and reliable.
Mainly tasks can be divided in three categories.
i. Developing quality plan
ii. Maintaining Quality in every aspect
iii. Preparing Quality Assurance report
4.1 Quality Plan
Quality plan is a document prepared by the quality department which depicts the job to be
performed as per the customer’s requirement. It includes the information like necessary
works to be performed before start of repair of manufacture, the material to be used, welding
electrode to be used, temperatures to be maintained, the tests to be carried out, the extent of
tests required machining processes to be employed, type of packaging to be used, and
requirement of assurance reports. So, in short quality plan is a document containing a set of
guidelines required for the respective job. It makes the job to be performed systematic and of
higher quality as the supervisor can easily direct and follow up the works carried out by the
workers as per the plan.
4.2 Quality Assurance
All aspects required by ISO 9001 standard are controlled by the quality system, which
includes the organizational structure, procedures, processes and resources for implementing
quality management. The main idea of setting up ISO 9001 quality system is to prevent
occurrence of any non-conformance through several of preventive measures. Despite of
different kinds of such systematic measures, the main QA measures for controlling site NDT
activities are: controlling NDT inspector qualifications, validness of test equipment and test
material, effectiveness of test procedures, impact of environmental conditions to test results,
and monitoring actual NDT performance by quality surveillance inspectors.
At NHE, the quality report is prepared and provided to the customer and donor or
investigating agency if any. For examples, the quality assurance report of repair and
maintenance of 4 runners and 60 guide vanes of Trisuli is scheduled to be provided to the
World Bank.

32. 19
4.2.1 Personal Qualification
Inspector qualification is essential to a reliable inspection, and it is also mandatory required
by regulatory bodies. NHE has such an NDT personnel qualification system that each
industrial sector has its specific requirements in addition to the basic NDT society
requirements. Therefore, in order to fulfill different requirements for different industrial
application, NHE NDT personnel hold different qualification certificate, including foreign
certificate, to satisfy different customers for different requirements. Although much expense
is spent for the training and qualification, NHE NDT personnel are well qualified in such a
way.
4.2.2 Test Equipment and Procedure
Test equipment and material are very important for NDT inspections. As an inspection
service organization, NHE developed and purchased all necessary equipment and materials
for services, including ultrasonic testing, radiographic testing, magnetic particle testing,
liquid penetrate testing, and visual testing. These equipment and materials are mainly used in
power generating industry and chemical industry for pressure vessel and related component
inspections.
4.2.3 Monitoring of NDT Processes
As an important quality assurance measure, quality surveillance inspectors are assigned to
verify the effectiveness of actual performance of NDT activities. The surveillance inspectors
have very good background knowledge of NDT, they check the prerequisite of testing for a
specific task, including NDT examiner's personnel qualification, status of test equipment and
materials to be used, test procedures adapted, and the environmental conditions presented.
They make sample checks to major test performance to verify if the test procedures are
followed by the NDT examiners. They check also the test results to verify if the results are
correct and the regulatory requirements are met. Of course, the responsibility of testing is still
on NDT examiner shoulders; the quality surveillance inspector is responsible for the
verifications. Such verifications are normally carried out by means of implementation of
witness and hold points inspections of quality plans for NDT testing.
4.2.4 Test Procedure
Test Procedures define the responsibilities, techniques, operational steps and control means
for specific method of testing and the objects. NHE establishes a series of test procedures for
different tasks, which we consider is necessary for carrying out quality services of testing.
4.2.5 Environmental Conditions
Environmental conditions affect the test results seriously on some occasions. Attention
should be taken for temperature, humidity, radioactive, and surrounding materials to the test
objects. For examples, the ultrasonic transmission sped in the steel changes about 8 m/s when
the temperature varies by a unit radioactive background of test objects affects the
radiographic testing results.
4.3 Quality Testing
The quality inspection is mainly performed by several of Non-Destructive Test (NDT). Under

33. 20
NDT following process are followed in NHE: -
 Radiography (X-Ray)
 Magnetic particle testing (MPT)
 Dye Penetration Test (DPT)
 Ultra-Sonic Testing (UT)
4.4 Welding Quality
Testing serves an important function in virtually all manufacturing processes. It ensures that
the final product’s quality matches the design specifications and is fit for the service
environments it will operate in.
There are many ways to classify testing techniques. One of the most popular classifications is
destructive and non-destructive testing.
Non-destructive testing refers to the use of testing techniques that do not alter any of the
properties of the tested product. These properties could be its strength, integrity, appearance,
corrosion resistance, conductivity, wear resistance, toughness and so on.
4.4.1 Liquid Penetrant Test(LPT)/ Dye Penetrant Test
Liquid Penetrant Test(LPT) is a popular non-destructive testing method used to identify
surface-level defects.
In this method, a low-viscosity liquid (penetrant) enters the surface defects such as cracks,
fissures and voids. The excess liquid is then wiped off and the specimen is left alone for some
time (penetrant dwell time).
A developer is then sprayed that allows the penetrant to move towards the surface. The
specimen is again left alone for a prescribed amount of time (developer dwell time).
Now, the surface inspection is done. If the dye is visible, it can be inspected with the naked
eye. In the case of fluorescent dyes, black light is needed for inspection.
We can detect surface discontinuities such as cracks, porosity, seams, laps and leaks using
this method.
Figure 9: NDT Chemical and Result

34. 21
4.4.1.1 Chemicals used in LPT/ DPT
1. Cleaner
Product name: Cleaner- GP
Producer: Pradeep metal treatment chemicals pvt.ltd
Packaging: 350ml/can
● The halogens and sulfur contents are controlled within acceptable limits of
specifications.
● Non corrosive to all the metals, operator friendly, highly efficient and efficient
to use.
● Meet requirements of international specifications for cleaner and LPT.
This is non-halogenated solvent cleaners suitable for pre-cleaning the job to make it ready for
penetrant testing. These cleaners are quite effective to remove oil, grease, loose rust, dirt, etc.
from the surface of the components so as to help effective penetration of penetrant materials
during tasting.
2. Penetrant
Product name: Penetrant- GP
Producer: Pradeep metal treatment chemicals pvt.ltd
Packaging: 350ml/can
Sensitivity: 1*20µ
Penetrant GP is solvent removal red color contrast penetrant, suitable for detection of
extremely fine surface defects which are found in castings, forgings, welds in all kinds of
ferrous & nonferrous metal working as well as on non-porous ceramic materials. This
Penetrant is not suitable for inspection of plastic components. The desired properties are well
controlled to obtain reliable & uniform results during application.
 Red Liquid gives bright defect indications under Day Light.
 Highly sensitive - detects 1 x 20 micron size cracks on Ni-Cr Panel
 Excellent Wetting ability - better coverage, non-toxic, non-corrosive, operator
friendly, no objectionable smell
 The aerosol cans contain non CFC environmental friendly hydrocarbon as propellant.
 Halogen and Sulfur controlled well within acceptable limits of most of the
International Specifications
3. Developer
Product name: Developer- GP
Producer: Pradeep metal treatment chemicals pvt.ltd

35. 22
Packaging: 350ml/ can
 Extremely fine particles give a uniform & Bright white non fluorescent
background to provide excellent contrast. Very High area coverage and hence
extremely cost effective.
 The Halogens & Sulfur contents are controlled within acceptable limits of
specifications
 Uniform and thin coating for optimum results during inspection
 Solvent suspendable Developers have well controlled drying time, within the
specifications limit, to increase blotting of penetrant from the defects.
 Non Corrosive to all the metals-Operator friendly - easy to use and remove
after application
4.4.1.2 Advantages of liquid penetrant tests:
● Works with many materials. Material properties such as magnetism, conductivity and
metallic/non-metallic do not matter Can spot tiny defects such as hairline cracks,
● Suitable for complex part geometries,
● Low cost,
● Can test large areas Portable
● Easy to use.
4.4.1.3 Disadvantages of liquid penetrant tests:
● The depth of defects is not known Risk of exposure to toxic fumes Cannot identify
subsurface defects Does not work with porous material,
● Time-consuming, generally needs more than 30 minutes,
● Messy operation, pre- and post-cleaning are necessary,
● Involves handling of chemicals and therefore not it’s not as safe as other methods.
Chemical disposal may also become an issue.
4.4.2 Ultrasonic Testing
Ultrasonic testing is the most popular nondestructive testing method after visual testing. In
this method, a high-frequency sound wave generated by a transmitter travels through the
object under test. The frequency of this wave is usually between 1 and 10 MHz.
The wave distorts when encountering a change in the density of the material. This change in
the transmitted wave is captured by a receiver.
The equipment then measures and analyzes the received wave to understand the nature and
depth of the defect. The equipment can also calculate the thickness of the specimen by
dividing the wave speed in the material by the time taken for travel.
We can identify defects such as cracks, abrasions, thinning, pitting and corrosion using
ultrasonic inspection.

36. 23
4.4.2.1 Advantages of ultrasonic testing:
● Quick, clean, reliable, portable
● Safe and easy to use
● Highly accurate and sensitive
● Ability to gauge dense materials
● Detection of surface and subsurface defects
● Identifications of minor defects not visible to the naked eye
4.4.2.2 Disadvantages of ultrasonic testing:
● Requires training Needs a smooth surface,
● Difficult to use with thin materials,
● Part geometry may create complications,
● Wave propagation speed in tested material must be known for accurate results
Couplants are required for smooth wave transfer from the transmitter to the specimen
Figure 10: UT Principle and Operation
4.4.2.3 Equipment
i. Pulsar
ii. Transducer
iii. Couplants
iv. Receiver/Amplifier
v. Display

37. 24
Figure 11: Various Form of Result During UT
4.4.3 Magnetic Particle Test
MPT is a popular NDT technique because of its fast execution where no surface preparation
is needed. In magnetic particle testing, the part is placed between permanent magnets or
electromagnets. The strength of the field is an important factor since a stronger field gives
better results. When the part under inspection is placed into the field, a magnetic current
starts flowing through the specimen. If there’s no defect, an uninterrupted magnetic flux field
is obtained.
But if it comes across a defect, the magnetic field bends and a part of it leaks out. This
leakage is also known as the flux leakage field.
In order to identify the defects via these leakage points, magnetic particles are used. These
particles are applied to the test specimen and they are pulled into these leakage points
because of the uneven magnetic flux density.
We may either use magnetic particles that can’t be seen with the naked eye or fluorescent
ones for better visibility. The width of the magnetic particle strips is wider than the defect’s
width. As a result, it can reveal minute defects with an opening width of up to 0.001 mm and
depth of 0.01 mm.With this technique, we can detect defects such as cracks, pores.
Figure 12: Basic Principle of MPT

38. 25
4.4.3.1 Advantages of Magnetic Particle Testing:
● Easy to use
● Portable setup
● High sensitivity
● Immediate results
● Usually inexpensive
● Can work through thin surface coatings
● Parts with complex geometries are also suitable
● Visual indication of the shape and size of the defect
● Can detect surface defects well. Also works for subsurface defects to an extent
4.4.3.2 Disadvantages of Magnetic Particle Testing::
● Can only test small areas at a time
● Does not work with non-magnetic materials
● Testing may burn the particle if the field is too strong Coatings thicker than 0.1 mm
need removal for testing
● Demagnetization of test specimens is necessary but may be tricky Can only work for
subsurface defects that have a depth of up to 3 mm
4.4.4 Radiographic Testing (RT)
RT is a non-destructive testing method which uses either x-rays or gamma rays to examine
the internal structure of manufactured components identifying any flaws or defects.
In Radiography Testing the test-part is placed between the radiation source and film (or
detector). The material density and thickness differences of the test-part will reduce the
penetrating radiation through interaction processes involving scattering or absorption. The
differences in absorption are then recorded on film or through electronic means. In industrial
radiography there are several imaging methods available, techniques to display the final
image, i.e. Film Radiography, Real Time Radiography (RTR), and Computed Tomography
(CT) etc.
There are two different radioactive sources available for industrial use; X-ray and Gamma-
ray. These radiation sources use higher energy levels, i.e. shorter wavelength, versions of the
electromagnetic waves. Because of the radioactivity involved in radiography testing, it is of
paramount importance to ensure that the Local Rules are strictly followed during operation.

39. 26
4.4.4.1 Advantages of RT:
● Can inspect assembled components
● Minimum surface preparation required
● Detects both surface and subsurface defects
● Provides a permanent record of the inspection
● Verify internal flaws on complex structures
4.4.4.2 Disadvantages of RT:
● Harmful radiations emitted during RT have adverse effect on health.
● Expensive method of testing
● Skilled and trained manpower is required
● Not portable

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Chapter-5: Human Resource and Project Management
HRM is concerned with the human beings in an organization. “The management of man” is a
very important and challenging job because of the dynamic nature of the people. No two
people are similar in mental abilities, tacticians, sentiments, and behaviors; they differ widely
also as a group and are subject to many varied influences. People are responsive, they feel,
think and act therefore they cannot be operated like a machine or shifted and altered like
template in a room layout. They therefore need a tactful handing by management personnel
HRM is the process of managing people of an organization with a human approach. Human
resources approach to manpower enables the manager to view the people as an important
resource. It is the approach through which organization can utilize the manpower not only for
the benefits of the organization but for the growth, development and self-satisfaction of the
concerned people. Thus, HRM is a system that focuses on human resources development on
one hand and effective management of people on the other hand so that people will enjoy
human dignity in their employment.
Among the various activities under the human resources, the following are quite noticeable: -
1) Maintaining Daily Record of employees
2) Calculating hours worked and over time of applicable.
3) Handling leave request of employees.
4) Preparing document foe sending employees on sites works.
5) Identifying the need of good manpower.
6) Observing and evaluating the work of every employees
5.1 Manpower Working at NHE
Figure 13: Manpower Working at NHE
Workforce Number
CEO 1
Division manager 5
Sr. Engineers/ Engineers 9
Officers(Technical/Administration) 9
Supervisors(Technical/Administration) 16
Technicians 42
Highly skilled workers 15
Skilled worker 15
Semiskilled worker 1
Unskilled workers 1
BTI apprentices 81
Project contact 37
Daily wages/Part time/Consultant 3
Total 235
5.2 Project Management
Project management is the practice of initiating, planning, executing, controlling, and closing
the work of a team to achieve specific goals and meet specific success criteria at the specified
time. A project is temporary in that it has a defined beginning and end in time, and therefore

41. 28
defined scope and resources. And a project is unique in that it is not a routine operation, but a
specific set of operations designed to accomplish a singular goal.
Project management processes fall into five groups:
i. Initiating
ii. Planning
iii. Executing
iv. Monitoring and Controlling
v. Closing
5.3 Stages of Project
5.3.1 Cost Estimation and Bidding
Typically, any project at NHE starts after the bidding has been accepted by the customer or
client. Based on the relevant information in the tender document, pre – costing, estimation is
done by the technical staff. During this part, every effort is made to make the estimated cost
as accurate as possible. The cost estimation must include all the sources of costs which
include but not limited to:
i. Material Cost Quotation and Purchasing
ii. Manpower – For design, fabrication, erection, and commissioning.
iii. Machine – Used for different operation, includes energy cost and deprecation cost
iv. Transportation
v. Accommodations – Manpower must be accommodated at sites
vi. Client / Guest Facilities
Then the company sets required profit margin and the bidding is made.
5.3.2 Contract Agreement
The actual inspection of the project is contract agreement between the bidder and the client.
Both the parties negotiate and set up the terms and conditions for the project. It in general
includes the project duration, obligations, from both parties, project cost, penalty to be
snapped in case of violation of the terms by either party, criteria for project expansion,
manufacturing details like materials to used, processes to be employed, quality consideration,
tests to be performed and so on.
5.3.3 Manpower Requirement
Any project requires a number of unskilled m, semi-skilled, skilled, and highly skilled
manpower including engineers and technicians. So, the project manager discusses with the
Human Resource Department about the quality and quantity of manpower required. Then, the
HR department looks for manpower within the company, and if needed vacancy is announced
for hiring manpower for the project. Now the team for the project is ready. It generally
includes.
i. Project Manager
ii. Engineers
iii. Supervisor
iv. Technical Officers
v. Draft man
vi. Skilled, semi-skilled, and un-skilled manpower

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5.3.4 Design
The next step is the designing of the system or product to be made. The Design includes.
i. All the parts, components, sub- assembly’s requirement.
ii. Detailed drawing of those parts or components.
iii. Assembly Drawing
This is very critical stage since the success of the entire project depends on the design made
by the engineers. Once the manufacturing is stated, any changes in design could result in
delaying in the project and huge losses to the company.
5.3.5 Procurement
Before staring the fabrication of component identifying a requirement or need of the
company through the final step of the award of the product or contract. This is made sure by
the procurement department.
Procurement Steps:
i. Need Recognition
ii. Delivery
iii. Specific Need
iv. Expediting
v. Source Options
vi. Receipt and Inspection of purchase
vii. Price and Terms
viii. Invoice Approval and Payment
ix. Purchase Order
x. Record Maintenance
5.3.6 Fabrication
The next step is the fabrication of product in the respective department at NHE. In general,
the fabrication is divided into several stages depending on the size of the project, and
planning is done for the project. The start and completion points are sets for each stage of
fabrication depending on the items required at certain time at the site for erection.
5.3.7 Transportation
Then the manufacturing components must be transported safely to site. The arrangements for
transportation are generally done by the bidding company.
5.3.8 Erection and Commissioning
After the components reach the site, theses component has to be assembled and installed
which is technically termed as erection. Then finally, the installed components have to be
tested in actual working condition. Again, some part of payment is made to the bidder after
erection and commissioning.

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Chapter-6: Welding
Welding is a fabrication process whereby two or more parts are fused together by means of
heat, pressure or both forming a joint as the parts cool. Welding is usually used on metals and
thermoplastics but can also be used on wood. The completed welded joint may be referred to
as a weldment.
The parts that are joined are known as a parent material. The material added to help form the
join is called filler or consumable. The form of these materials may see them referred to as
parent plate or pipe, filler wire, consumable electrode (for arc welding), etc.
Consumables are usually chosen to be similar in composition to the parent material, thus
forming a homogenous weld, but there are occasions, such as when welding brittle cast irons,
when filler with a very different composition and, therefore, properties is used. These welds
are called heterogeneous. The completed welded joint may be referred to as a weldment.
6.1 Types of Welding
On the basis of process type welding are classified as
6.1.1 Metal Inert Gas (MIG) Welding
Metal Inert Gas (MIG) welding is an arc welding process that uses a continuous solid wire
electrode heated and fed into the weld pool from a welding gun. The two base materials are
melted together forming a joint. The gun feeds a shielding gas alongside the electrode helping
protect the weld pool from airborne contaminants.
MIG welding is a versatile technique suitable for both thin sheet and thick section
components. An arc is struck between the end of a wire electrode and the work piece, melting
both of them to form a weld pool. The wire serves as both heat source (via the arc at the wire
tip) and filler metal for the welding joint. The wire is fed through a copper contact tube
(contact tip) which conducts welding current into the wire. The weld pool is protected from
the surrounding atmosphere by a shielding gas fed through a nozzle surrounding the wire.
Shielding gas selection depends on the material being welded and the application. The wire is
fed from a reel by a motor drive, and the welder moves the welding torch along the joint line.
The gasses which are used for various metal are:
● Steels: CO2,argon +2 to 5% oxygen, argon +5 to 25% CO2
● Non-ferrous (e.g. Aluminum, copper or nickel alloys):argon, argon / helium
The functions of shielding gas are:
● forms the arc plasma
● stabilizes the arc roots on the material surface
● Ensures smooth transfer of molten droplets from the wire to the weld pool.

44. 31
Figure 14: MIG Welding Schematic
(lrdesigns, 2021)
6.1.2 Tungsten Inert Gas (TIG) Welding
Tungsten Inert Gas (TIG) welding, also known as Gas Tungsten Arc Welding (GTAW) is an
arc welding process that produces the weld with a non-consumable tungsten electrode. In the
TIG welding process the arc is formed between a pointed tungsten electrode and the work
piece in an inert atmosphere of argon or helium. The small intense arc provided by the
pointed electrode is ideal for high quality and precision welding. Because the electrode is not
consumed during welding, the TIG welder does not have to balance the heat input from the
arc as the metal is deposited from the melting electrode. The welding arc can be started by
scratching the surface, forming a short-circuit. Electrodes for DC welding are normally pure
tungsten with 1 to 4% thoria to improve arc ignition. In AC welding, as the electrode will be
operating at a much higher temperature, tungsten with a zirconia addition is used to reduce
electrode erosion.
The shielding gas is selected according to the material being welded. Argon is most
commonly used gas while, 2-5% Hydrogen gas is used to get cleaner looking welds without
surface oxidation but increases risk of hydrogen cracking in carbon steel and weld metal
porosity in aluminum alloys.
Figure 15: TIG Welding Schematic

45. 32
(lrdesigns, 2021)
6.1.3 Submerged Arc Welding( SAW)
Submerged arc Welding (SAW) is the joining process that forms an electric arc between a
continuously fed electrode and the work piece to be welded. A blanket of powdered flux
surrounds and covers the arc and, when molten, provides electrical conduction between the
metal to be joined and the electrode. It also generates a protective gas shield and a slag, all of
which protects the weld zone.
In SAW an AC arc is formed between a heavy gauge work piece and a continuously fed
electrode. The arc is shielded by a directly deposited granular flux material of several
possible varieties. This flux stream is fed over the weld zone to provide the exclusion of
atmospheric contamination and a reducing environment. It also acts to contain some of the
arc energy in the melt pool, enhancing weld quality and improving the application of energy.
Submerged arc welding is commonly used for welding thick sections of steel, especially in
applications such as shipbuilding, structural steel fabrication, pressure vessel manufacturing,
and pipeline construction. It offers high deposition rates and throughout, deep penetration
capabilities, excellent weld quality, and the potential for simple automation to reduce reliance
on skilled labor.
Figure 16: Submerged Arc Welding
(Gupta, 2023)
6.1.4 Arc Welding
Arc welding is a welding process that is used to join metal to metal by using electricity to
create enough heat to melt metal, and the melted metals, when cool, result in a binding of the
metals. It is a type of welding that uses a welding power supply to create an electric arc
between a metal stick ("electrode") and the base material to melt the metals at the point of
contact. Arc welding power supplies can deliver either direct (DC) or alternating (AC)
current to the work, while consumable or non-consumable electrodes are used. The electrodes
come in a vacuum shield pack so that the air cannot degrade the quality of electrodes.
The electrodes used in this division have specific codes. Welding electrode codes
standardized by the American Welding Society (AWS), and consists of a letter followed by

46. 33
four digits. The letter indicates the type of coating on the electrode, while the four digits
provide specific information about the electrode’s composition and capabilities.
Figure 17: Electrode Specification and Arc Welding
(Brothers, 2023)
The first two digits of the classification number indicate the minimum tensile strength of the
weld metal in thousands of pounds per square inch (ksi). For example, an electrode with a
classification of E6010 has a minimum tensile strength of 60 ksi.
The third digit of the classification number indicates the position capability of the electrode.
A “1” indicates that the electrode can be used in all positions; a “2” indicates that it can be
used in the flat and horizontal positions, and a “3” indicates that it can only be used in the flat
position.
The fourth digit of the classification number indicates the type of current that can be used
with the electrode. A “0” indicates that the electrode can be used with direct current (DC) or
alternating current (AC), while a “1” indicates that it can only be used with DC.

47. 34
6.2 Welding Techniques in NHE
6.2.1 Metal Inert Gas (MIG) Welding
NHE uses MIG technique in order to weld
metals like stainless steel and mild steel. As
per the working person a cylinder of shielding
gas lasts for a week. In NHE both MS and SS
are welded during which carbon dioxide and
argon mixture is used for steels and only argon
for aluminum or nickel alloy. MIG consumes
1 roll of filler of 1.2 mm diameter and net
weight of 15kg in 2 busy days.
Figure 18: MIG Welding Setup
6.2.2 Tungsten Inert Gas
In NHE TIG welding is done where high quality and clean welds are required such as repairing of
hydro mechanical components such as guide vanes, side plates, thrust pad etc. It uses 2.4 * 1000 mm
(diameter * length) tungsten wire. It uses argon as shielding gas. According to the workman, a
cylinder of argon lasts for a month.
Figure 19: TIG Welding Setup

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6.2.3 Submerged Welding
IN NHE submerged welding is used for
welding thick plates such as penstock.
Recently this method was used to weld the
penstock of Khimti Hydropower, Rasuwa.
This method is preferred because it has less
distortion, strong weld, deep weld
penetration, high deposition rate and
minimal edge preparation.
Figure 20: Slag from Submerged Welding
6.2.4 Arc Welding
NHE uses arc welding technique mainly to weld mild steel metal of thickness up to 10 mm. The
major electrode used in NHE has coding of AWS/SFA 5.1 E 7018 IS: EB 5426 H3 JX. It is the most
common welding technique used here. As per the inspection there are about 15 welding machines.
The current used is of AC type and the electrodes used are treated in the oven so that the chances of
cracks and discontinuity in the welding can be prevented.
Figure 21: Most Common Electrode Used in NHE
6.3 Welding Codes and Standards
A welding code or standard is a detailed listing of the rules or principles that are to be applied to a
specific classification or type of product.
A welding specification is a detailed statement of the legal requirements for a specific classification
or type of weld to be made on a specific product. Products manufactured to code or specification
requirements commonly must be inspected and tested to ensure compliance.

49. 36
The most common used codes or regulations are API Standard 1104, American Petroleum Institute—
Used for pipelines, ASME Section IX, American Society of Mechanical Engineers—Used for
pressure vessels and nuclear components, and AWS D1.1, American Welding Society—Used for
bridges, buildings, and other structural steel.
6.3.1 Welding Thin Metals
While SMAW is known for excellent results when welding through dirt or rust, you want to clean
surfaces when dealing with thin metals, especially when working with E6013 electrodes. Also,
leaving a large gap is not recommended, as pieces will distort, so a nice fit-up is required.
Since it is challenging to control heat input with SMAW, you will need extra attention with thinner
material. That explicitly applies when using longer welds. Using the skip welding technique with a
number of intermittent or stitch welds can help minimize distortion and evenly distribute the heat.
In addition, you can clamp the pieces and use tack welds with an added backing bar that can serve as
a heat sink. Sometimes electrodes can coil up and down, so you could use the used electrodes or
provide tighter support. Going slow will result in a burn-trough, but you should do more than run
through the weld.
You will need to set the machines low enough not to burn through base metal but still high enough to
get an arc start.
The next step will be selecting the right Stick welding rod. Use less than 1/8″ or 1/16″ diameter
electrodes, as they will extend the heat-affected zone, leading to wrapping or distortion. You should
use an E6011 or an E6013 rod for the best results. For thin metals, DCEN (Direct Current Electrode
Negative or DC) is the better choice as it offers lower penetration compared to DCEP (Direct Current
Electrode Positive or AC).
6.3.2 Welding Medium Thickness Metals
As a medium-thick metal, we consider plates up to 1/4” or 1/2" since you will rarely get a chance to
weld anything thicker than that in your shop. Stick welding medium-thickness metal is certainly
more forgiving than welding sheet metal, but you will still need some time to master the technique
for the best results. Current and polarity settings will vary on the selected electrode and overall
project requirements.
The amperage is usually stated on the box or enclosed materials of the electrode package. You can
use a rule of thumb that says 1 amp for each .001-inch electrode diameter. Low amperage will cause
the electrode to stick excessively to the piece, eventually resulting in arc stuttering. Conversely, high
amperage makes the weld pool extremely fluid and almost uncontrollable, with high arc sounds.
While it is less likely to burn through medium-thickness metal, you should still pay attention. The arc
length represents the distance between the electrode and the puddle. As a rule of thumb, it should not
exceed the diameter of the core of the electrode. If you keep the electrode too close, it will stick and
extinguish. Meanwhile, lifting it way up high will cause spatter, porosity, or undercut. Travel speed
should be adjusted to the thickness of the metal. Low travel speed creates wider weld beads with
shallow penetration. Meanwhile, fast travel speed creates narrow weld beads; again, with penetration
problems and fear of undercut or under fill.

50. 37
Figure 22: Variation of Beads Form on Different Conditions
(Guo, 2022)
6.3.3 Welding Thick Metals
Stick welding is one of the most suitable and widely used methods for joining thicker metal in farm
and ranch, on the field, and in plant maintenance and repair, pipeline welding, and shipbuilding
applications because of high deposition and penetration, with low costs. You will need a 1/8-inch or
5/8-inch rod for the first, initial, or root pass and a 5/32 or a 3/16-inch rod for filler and cap passes.
An all-position cellulose E-XX10 welding electrode is used (6010, 7010, 8010).For plates up to
3/16" thick, you should use a V-bevel to prepare the pieces. 1/2" to 3/4" pieces will require a U-
bevel, which can take more filler metal to ensure stronger welds. Finally, pieces thicker than 3/4 inch
will need a double V or U-bevel joint configuration. The standard travel speed is 12 inches per
minute, with reverse (DC+) polarity. This approach creates a strong foundation for the upcoming
welds with slag that easily falls off.
Figure 23: Different Joints for Different Thickness of Metal
(Bale, 2022)

51. 38
Joint type Thickness
Square butt joint Up to 1
⁄4 in (6.35 mm)
Single-bevel joint 3
⁄16–3
⁄8 in (4.76–9.53 mm)
Double-bevel joint Over 3
⁄8 in (9.53 mm)
Single-V butt joint Up to 3
⁄8 in (9.53 mm)
Double-V butt joint Over 3
⁄8 in (9.53 mm)
Single-J joint 1
⁄2–3
⁄4 in (12.70–19.05 mm)
Double-J joint Over 3
⁄4 in (19.05 mm)
Single-U joint Up to 3
⁄4 in (19.05 mm)
Double-U joint Over 3
⁄4 in (19.05 mm)
6.3.4 Types of Electrode
1. CHE40 (E 6013)
Product Name: AWS E6013 Welding Electrode
Size: 2.5mm*300mm,
Package: 2.5 kg/inner box, 8 boxes/ carton=20kg
Purpose: Mild steel arc welding
Current range: 50-90 A
Redrying: 150-170 ℃, 0.5-1 hrs
Producer: Atlantic