A

Training report
On
“HEAVY FABRICATION”
At
BHEL HARIDWAR

Submitted in partial fulfilment of requirements for the diploma of

Mechanical Engineering

Submitted By: Submitted To:

RAJAN MR.DEEPESH SINGH
POLYTECHNIC . (Final Year) Sr.Engr.-Bay-1,Bock-2

GOVT.POLYTECHNIC POKHARI CHAMOLI

2017-20
 ACKNOWLEDGEMENT

“Inspiration and motivation have always played a key role in the success of any
venture.”

Success in such comprehensive report can’t be achieved single handed. It is

the team effort that sail the ship to the coast. So I would like to express my sincere
thanks to my mentor MR.NARENDRA SINGH RANA Sir.

I am also grateful to the management of Bharat Heavy Electrical limited

(BHEL), Haridwar for permitting me to have training during June 2th to July 2th, 2012.

It gives me in immense pleasure to express my gratitude to the department of

Mechanical Engineering for their prudent response in course of completing my
training report. I am highly indebted to, MR. DEEPESH SINGH, their guidance and
whole hearted inspiration; it has been of greatest help in bringing out the work in the
present shape. The direction, advice, discussion and constant encouragement given by
them has been so help full in completing the work successfully

[i]
 INDEX
SR.NO. TROPIC PAGE.NO

1. HEAVY FABRICATION 1– 2
1.1 DEFINATION 1

1.2 PROCESSES
1
1.3 APPLICATIONS 1

1.4 RAW MATERIAL 2

2. METAL CUTTING 3– 5
2.1SHEARING MACHINE 3

2.2 PLASMA CUTTING 4

2.3 OXY-FUEL CUTTING 5

3. BENDING 6–8
3.1 HYDRAULIC PRESS 6

3.2 ROLLING MACHINE

7-8

4. WELDING 9 – 12
4.1 TIG WELDING 9

4.2 MIG WELDING 10

4.2.1. CARBON DIOXIDE WELDING 11

4.3 GOUGING 12

5. INSPECTION 13– 14
5.1 VISUAL INSPECTION 13

5.2 RADIOGRAPHY 13

5.3 PENETRATE TEST 13

 5.4 ULTRASONIC FAULT DETECTOR 13-14

6. MACHINING 15– 20
6.1 VERTICAL BORING MACHINE 15

6.2 PLANER MACHINE 16

6.3 MANIPULATOR MACHINE 17

[iii]
6.3.1PURPOSE 17

6.3.2 SPECIFICATIONS 18

6.4 COPY MILLING MACHINE 19

6.5 CENTRAL LATHE WITH THREE & FOUR JAWS 20

7. SHOT BLASTING 21– 22

7.1 PURPOSE 21

7.2 SCOPE 21

7.3 SHOT DIRECTION 21

7.4 SETTING PARAMETER 22

8. BLOCK DESCRIPTION 23 – 25
8.1 PREPARATION, BAY-1 23

8.2 ASSEMBLY & WELDING SECTION,BAY-2 24

8.3 BAY -3 24

8.4 BAY- 4 25

9. MANUFACTURING PROCESSES 26– 28

10. CONCLUSION 29

[iv]
 INTRODUCTION

BHEL is the largest engineering and manufacturing enterprise in India in the

energy related infrastructure sector today. BHEL was established more than 40 years ago
when its first plant was setup in Bhopal ushering in the indigenous Heavy Electrical
Equipment Industry in India a dream which has been more than realized with a well
recognized track record of performance it has been earning profits continuously since
1971-72.

BHEL caters to core sectors of the Indian Economy viz., Power Generation's &
Transmission, Industry, Transportation, Telecommunication, Renewable Energy, Defense,
etc. The wide network of BHEL's 14 manufacturing division, four power Sector regional
centers, over 150 project sites, eight service centers and 18 regional offices, enables the
Company to promptly serve its customers and provide them with suitable products,
systems and services – efficiently and at competitive prices. BHEL has already attained
ISO 9000 certification for quality management, and ISO 14001 certification for
environment management.

T he company’s inherent potential coupled with its strong performance make this one
of the “NAVRATNAS”, which is supported by the government in their endeavor to
become future global players.
 1. HEAVY FABRICATION

1.1. DEFINATION:-

Fabrication as an industrial term refers to building metal structures by cutting,

bending and assembling. The cutting part of fabrication is done via sawing, shearing, or
chisel machine (all with manual and powered machine variants); torching with handheld
torches (such as oxy-fuel torches or plasma torches); and via CNC cutters (using a laser,
torch, or water jet). The bending is done via hammering (manual or powered) or via press
brake and similar tools. The assembling (joining of the pieces) is via welding and binding
with adhesives, riveting, threaded fasteners, or even yet more bending in the form of a
crimped seam. Structural metal and sheet metal are the usual starting materials for
fabrication, along with the welding wire, flux, and fasteners that will join the cut pieces.
As with other manufacturing processes, both human labor and automation are commonly
used. The product resulting from (the process of) fabrication may be called a fabrication.

1.2. PROCESS:-

Processes involved in Fabrication are:-

x Cutting & Burning.

x Forming x
Machining. x
Welding.

1.3. APPLICATIONS:-

x Equipment for Industrial Applications.

x Equipment for Specialty Gases Applications.

1.4. RAW MATERIAL

Standard raw materials used by metal fabricators are:-

1
x Plate metal x Formed and
expanded metal x Tube stock x
Square stock x Sectional
metals ( I beams, W beams, C-
channel ) x Welding wire x
Castings x Fittings

FIG.1 PROCESSES PERFORMED IN HEAVY FABRICATION

2
 2. METAL CUTTING

2.1. SHEARING MACHINE:-

A shearing machine is hydraulic machine used to cut metal work-pieces with help of
Shearing mechanism. In this machine the metal work-piece are passed through the machine
through roller transmitters called guides which moves too-and fro and then stopped with
help brake stops which works hydraulically which operates by pressing foot pedal provided
at the foot of machine setup. These stops hold the work-piece tightly so that it doesn’t
disturb due to high impact of shearing cutters. Then valve is operated which causes the
fluid to pressurize and further moving the cutter down which strikes the work-piece and
causing cutting action of work-piece. Metals that can be cut are mild steel, stainless steel
etc. Maximum thickness that can be cut is 10mm. Main component of Shearing machine
is as follow:-

a) Jack:-support the plate or metal parts which are to be cut.

b) Blade:-cutting the metal parts (cutter).
c) Guide:-Numerical controlled length adjustment.
d) Hydraulic Oil tank.

FIG.2 CNC SHEARING MACHINE

3
2.2 PLASMA CUTTING:-

Plasma cutting is a process that is used to cut steel and other metals (or sometimes
other materials) using a plasma torch. In this process, an inert gas (in some units,
compressed air) is blown at high speed out of a nozzle; at the same time an electrical arc
is formed through that gas from the nozzle to the surface being cut, turning some of that
gas to plasma. The plasma is sufficiently hot to melt the metal being cut and moves
sufficiently fast to blow molten metal away from the cut.

P l a sma cutters have also been used in CNC machinery. Manufacturers build CNC
cutting tables, some with the cutter built in to the table. The idea behind CNC tables is to
allow a computer to control the torch head making clean sharp cuts. Modern CNC plasma
equipment is capable of multi-axis cutting of thick material, allowing opportunities for
complex welding seams on CNC welding equipment that is not possible otherwise.
Welding torch used has outer torch made up of brass and inner one made of copper.
Minimum gap between torch and work-piece is 5mm.

This machine can be used to cut the work-piece of mild steel and stainless steel.
The differences between the cutting methods for both of these metals are the use of nozzles
& the pressure of gases applied to pass through nozzles so that cutting action is done easily.
Work-piece of thickness 100mm to 210mm can be cut from this type machine. For e.g. For
a mild steel job of thickness 100mm the cutting speed is 131.55mm/min.

Gases used in this type of machine are oxygen and Bharat Metal Cutting Gas
(BMCG). Oxy-acetylene is avoided due to less purity& heavier as compared to BMCG. It
is less pure which causes repeated cleaning of burner.

The gap between Nozzle & plate is 5mm. If gap is increased sensor adjust the
pressure according to it. Large diameter Nozzle is used for thick metal sheet & higher
pressure and vice versa for thin metal sheet.

4
 FIG.3 CNC PLASMA CUTTING MACHINE 2.3. OXY-FUEL
CUTTING:-

Oxy-fuel cutting is the most widely applied process for cutting mild steels and low
alloyed steels. The process covers the entire thickness range from 1 mm to 2500 mm (0.04-
100 inches), it gives an excellent cut quality and the investment costs are low. Furthermore
the process can easily be mechanized. Oxy-fuel cutting is a combustion process. An
oxygen jet burns the metal in a narrow section to make a cut and removes the combustion
products (slag) from the kerfs. The purity of the cutting oxygen is of great importance for
the cutting speed that can be achieved. A higher purity level means a higher cutting speed.
Oxy-fuel cutting are processes that use fuel gases and oxygen to either weld or cut metals.

In Oxy-fuel cutting, a cutting torch is used to heat up ferrous metal to kindling

temperature (about 980°C). A stream of pure oxygen is trained on the hot metal which
chemically combines with the iron which then flows out of the cut, or kerfs, as an
ironoxide slag. There have been examples of oxy-hydrogen cutting sets with small (scuba
sized) gas cylinders worn on the user's back in a backpack harness, for rescue work.

5
 3. BENDING
Bending is a process by which metal can be deformed by plastically deforming the
material and changing its shape. The material is stressed beyond the yield strength but
below the ultimate tensile strength. The surface area of the material does not change much.
Bending usually refers to deformation about one axis.

3.1. HYDRAULIC PRESS:-

A hydraulic press is a hydraulic mechanism for applying a large lifting or

compressive force. It is the hydraulic equivalent of a mechanical lever, and is also known
as a Bramah press after the inventor, Joseph Bramah. Hydraulic presses are the most
commonly-used and efficient form of modern press.

The hydraulic press depends on Pascal's principle: the pressure throughout closed
system is constant. At one end of the system is a piston with a small cross-sectional area
driven by a lever to increase the force. Small-diameter tubing leads to the other end of the
system. A fluid, such as oil, is displaced when either piston is pushed inward.

The small piston, for a given distance of movement, displaces a smaller amount of
volume than the large piston, which is proportional to the ratio of areas of the heads of the
pistons. Therefore, the small piston must be moved a large distance to get the large piston
to move significantly. The distance the large piston will move is the distance that the small
piston is moved divided by the ratio of the areas of the heads of the pistons.
There were two hydraulic presses at present which are:

x CNC Back Press-340 ton. x Manually

operated- 400 ton, 800 ton.
 6

FIG.4 CNC BACK PRESS MACHINE

3.2. ROLLING MACHINE:-

THREE ROLL BENDING MACHINE: Roll benders use three rolls (typically) to bend
solids, extrusions and tube and pipe to various diameters by adjusting one or two rolls. The
pyramid style roll benders have one moving roll, usually the top roll. Double pinch type
roll benders have two adjustable rolls, usually the bottom rolls, and a fixed top roll.
Large arcs, circles and spirals are typical applications for roll benders.

The roll bending machine in BHEL has following specifications:-

S.R.NO. SPECIFICATIONS DIMENSIONS

1. MAXIMUM WORKING LENGTH 8000 MM
2. MINIMUM DIAMETER OF FORMING 1300 MM
3. PLATE THICKNESS 32 MM
4. UPPER ROLL DIAMETER 7550 MM
7
 5. LOWER ROLL DIAMETER 680 MM
6. SPEED OF FORMING 5 M/MINUTE
7. SPEED OF LOWERING UPPER ROLL 60 MM/MINUTE
8. SPEED OF RAISING UPPER ROLL 120 MM/MINUTE
TABLE 4- SPECIFICATION OF THREE ROLL BENDING MACHINE

FIG.5 THREE ROLL BENDING MACHINE

4. WELDING
Welding section is the most important section of this block as all the main parts of
Steam Turbine from generator to casing or from shafts to blades requires welding to join
their surfaces. Mainly the welding methods used are Shielded Metal Arc Welding (MIG),
Carbon Di-oxide welding (MIG welding) and TIG welding etc.
8
 Air Products' shielding gases are commonly used in several welding processes,
mostly MIG and TIG welding. The selection of a suitable welding gas is essential for the
welding process. The welding gas not only protects the weld metal from the surrounding
air, it can also contribute to higher productivity and to better mechanical properties of the
weld. Air Products offers a full range of standard shielding gas mixtures for MIG welding
for all common material types.

4.1. TIG WELDING:-

TIG welding is a high-quality welding technique with a low fusion rate. The arc
burns between a tungsten electrode and the work piece; the electrode does not melt, so it
acts only as a current conductor and arc carrier.

T h e shielding gases protect the weld area from atmospheric gases, such as oxygen,
nitrogen, carbon dioxide, and water vapor. Depending on the materials being welded, these
atmospheric gases can reduce the quality of the weld or make the welding process more
difficult to use.

In this type of welding, tungsten electrode is used which is non-consumable. Filler

material used is either copper wire or wire of same material to be weld. When current
through tungsten electrode is passed, than a spark is produced, which is of a very high
intensity. Along with above a blow of argon gas is passed through holder to provide inert
atmosphere at welding.

The strength of TIG welding is more than any other type of welding. The
temperature of flame is varied by adjusting voltage/ current as per requirement. This type
of welding is used mainly for welding pipes. Defects occur mainly in this type of Welding
is porosity caused by stopping the flow of argon gas.

9
 FIG.6 TIG WELDING

4.2. MIG WELDING:-

In MIG welding, the metal electrode is used to produce spark. The current is
allowed to flow through filler metal which passes through welding holder & a blow of
gases is passed through holes provided on holder which provide safeguard to welding area
from atmospheric gases. Voltage can be adjusted according the speed of filler material,
feeding is adjusted as per requirement.

FIG.7 MIG WELDING

10
4.2.1. CARBON DIOXIDE WELDING:- In this type of welding, copper coated wire is
made in contact with metal to be weld and then high current is allowed to flow through
wire which causes spark of very high intensity . Then carbon dioxide & argon gas is blown
to welding area which helps in maintaining the inert atmosphere nearby welding area and
free from oxygen. Composition of carbon dioxide & argon gas is 80:20(%).Temperature is
maintained at 3600 to 4000ºC.

The strength of Welding with CO2-gas welding is much better as compared to metal
Arc. So for mass production and high productivity with greater quality this welding method
is used. Main defect of carbon dioxide welding is porosity.

FIG.8 CO2WELDING MACHINE 4.3. GOUGING:-

Thermal gouging is an essential part of welding fabrication. Used for rapid removal
of unwanted metal, the material is locally heated and molten metal ejected usually by
blowing it away. Normal oxygen fuel gas or arc processes can be used to produce rapid
melting and metal removal.

Manual metal arc Gouging is a process in which a process a electrical arc is

generated to melt the material. Other techniques like special electrodes or a jet of

11
compressed air are used to blow away the molten material. No specific high purity or
compressed gases are needed in these processes.

FIG.9 GOUGING CARBON ELECTRODE

5. INSPECTION
Usually in BHEL Nondestructive testing (NDT) is performed. It is defined as
comprising those test methods which are used to examine an object, material or system
without impairing its future usefulness. The term is generally applied to non medical
investigations of material integrity. The main NDT processes at the fabrication block are
as follows:-

5.1. VISUAL INSPECTION

It is the simplest, cheapest and most widely used method amongst the entire NDT’s.
A simple visual test reveals gross surface defects easily and quickly. However for
detection of final defects, device/equipments having high degree of precision and
illumination are required.

5.2. RADIOGRAPHY

In this test the X-rays and gamma rays are used to detect deep seated internal
defects. The short wavelengths of X-ray permitted to penetrate through the opaque

12
 material. Gamma rays are the electro-magnetic radiations that are emitted from an
unstable nucleus.

5.3. PENETRATE TESTING

Penetrate solution is applied to the surface of a pre-cleaned component. The liquid

is pulled into surface-breaking defects by capillary action. A developer is applied
to pull the trapped penetrate back to the surface where it is spread out and forms an
indication. The indication is much easier to see than the actual defect.

5.4. ULTRASONIC FAULT DETECTOR

In this process job is painted with oil and then high frequency sound waves is passed
through the job. Then the echo is recorded on detector. If the echo is recorded with
disturbance earlier than the other end then the job is defective.

FIG.10 DEFECT DETECTED BY ULTRA SONIC FAULT DETECTOR

13
 6. MACHINING
Machining can be defined as the process of removing material from a work piece
in the form of chips .The term metal cutting is used when the material is metallic. Most
machining has very low set-up cost compared to forming, molding, and casting processes.
However, machining is much more expensive for high volumes. Machining is necessary
where tight tolerances on dimensions and finishes are required.

6.1. VERTICAL BORING MACHINE

In this machine there is one Ram Head On Cross Rail, Jaw Chucks, and
Automatic Lifting & Lowering of Cross Rail. There is Lubrication System on all Sliding
Ways to avoid frictional losses. A Centralized Control Station with Interlocked Electrical
Control Pane is provided. A Set of Service tools is also provided. Some Special
Accessories are also provided with this machine like as follows:-

a) Additional Ram Head On Cross Rail.

b) Turret Head On Cross Rail.
c) Threading Head On Cross Rail.
d) Side Ram Head.
e) Slotting Attachment On Cross Rail

FIG.11 VERTICAL BORING MACHINE

14
6.2. PLANNER MACHINE

A planner is a type of metal working machine tool that is analogous to a shaper,

but larger, and with the entire work piece moving beneath the cutter, instead of the cutter
moving above a stationary work piece. The work table is moved back and forth on the bed
beneath the cutting head either by mechanical means, such as a rack and pinion gear, or by
a hydraulic cylinder. The carriage is heavy duty and long to gives balanced bearing to the
bed even at the end of the stroke. The bed is of heavy duty box type construction. It is
ribbed throughout the length and breadth giving vibration free movement under the heaviest
cut. Table is heavily ribbed and proportionally dimensioned heavy duty close grained cast
iron box type construction. It has 'v' slides matching the 'v' grooves on the bed and is hand
scrapped to give oil film lubrication. Cross slide has a box type construction carrying the
tool slide which can be operated by hand as well as by automatic feed. Gearbox consists of
Machine Cut gears running in anti friction bearings with oil immersed. Tool post is a cast-
iron close grained construction. Tool holders machined out of steed blocks. Uprights are
Heavy duty cast iron construction bolted to the sides of the bed .ribbed inside to avoid
vibration. Operations that can be performed by it:-

a) Vertical planning.
b) Horizontal planning.
c) Angular Planning.
d) Slot Cutting.

15
 FIG.12 PLANNER MACHINE

6.3. MANIPULATOR MACHINE

Parts that cannot be welded easily by ordinary welding, especially internal curved
parts are welded using manipulators. In manipulator machine parts to be welded is fixed
with the help of fixture attached to the table of the manipulator machine. Table can be rotate
through 0º-360º and tilting of table is 0º-135º

6.3.1 PURPOSE:- Metal parts which are heavier in weight and difficult to change their
position can be weld by the use of manipulator machine which can change the position of
parts according to our requirement. Guide blade carriage blade is weld by the use of
manipulator machine. Carriage or ring is mounted on the table with the help of fixture and
then guide blade carrier blade is weld to the inner ring to both side of curved surface by
tilting the table

6.3.2 MACHINE SPECIFICATION

a) Gross weight = 7600 kg.

b) Size =393*383*180 cm3.

16
 c) Table diameter = 3500mm (without extension), 4500mm (with
extension).
d) Rotation of table = 00 to 3600 (clockwise or anti clock)
e) Tilting of table = 00 to 1350.
f) Table rotation speed = 0.012-0.5 rpm.

FIG.13 MANIPULATOR HOLDING GBC (GUIDE BLADE CARRIER)

6.4. COPY MILLING MACHINE

This machine is designed for milling profiles or relief contours (three-dimensional

milling) on articles made of various materials by means of a cutting tool (milling cutter),
which reproduces on the article the surface or contour of a master device—for example, a
master cam in the shape of a flat template, a three-dimensional model, or a contour drawing.
The master device is mechanically, pneumatically, or hydraulically connected to a
servomechanism, which directs the cutting tool.

17
 The servomechanism acts on an amplifying device on the one hand and, on the other
hand, on an actuating device. Hydraulic, electromagnetic, or electro-optical relays are used
in the amplifying devices of such machines. The actuating member may be a screw, a slide
valve, an electromagnetic coupling, a solenoid, a differential, or some other device, and it
may be driven by an electric motor or a hydraulic power cylinder.

FIG.14 COPY MILLING MACHINE

6.5 CENTRE LATHE WITH THREE AND FOUR JAWS:

A metal lathe is generic description for a rigid machine tool designed to remove
material from a work piece, through the action of a cutting tool. They were originally
designed to machine metals; however, with the advent of plastics and other materials, and
with their inherent versatility, they are used in a wide range of applications, and a broad
range of materials.

A center lathe is a dual head machine where the work remains fixed and the heads
move towards the work piece and machine a center drill hole into each end. The resulting

18
work piece may then be used "between centers" in another operation. The usage of the term
metal lathe may also be considered somewhat outdated these days, plastics and other
composite materials are in wide use and with appropriate modifications, the same principles
and techniques may be applied to their machining as that used for metal.

A center lathe or engine lathe may be considered the basis for the metal lathe and
is the type most often used by the general machinist or hobbyist. The center lathe may be
considered a useful starting point. The engine lathe is the name applied to a traditional 20th
century lathe. It is assumed that the 'engine' was added to the description to separate them
from the 'foot lathes' (lathes turned by pedals) or other hand rotated pieces of machinery.
Early engine lathes were generally 'cone heads', in that the spindle usually had attached to
it a multi-step pulley designed to accept a flat belt.

FIG.15 LATHE MACHINE

19
 7. SHOT BLASTING

7.1. PURPOSE

Used for hardening the root of the low pressure rotor turbine blade in fatigue load.
Shot blasting is carried out to introduce compressive stress to depth of blade. In blades,
fatigue strength and improvement in resistance to stress omission is checked along with
corrosion removal.

Blasting process consists of bombarding exposed surface of fir tree root with steam
of hardened spherical metallic dots from robotics controlled nozzle by applied air pressure.

7.2. SCOPE

Shot blasting of steam turbine blade roots with cast steel shots type S280 to S390
in blasting intensity of range 0.3 to 0.35.

7.3. SHOT DIRECTION

Notch radii should be blasted in average normal direction. This blasts that steel
shots have to hit the radius in perpendicular direction since blasting is most effective under
this condition. Nozzle has to be point to centre of root curve.

7.4. SETTING PARAMETER: The setting parameters for machine are:-

a) Air pressure
b) Shot size
c) Nozzle diameter
d) Shot flow
e) Distance between blasted surface and nozzle.
f) Blasting time
g) Reservoir pressure

20
 FIG.16 SHOT BLASTING MACHINE

8.1 PREPARATION, BAY -1

It has the following sections:

a) Marking cutting and straightening section.

b) Gas cutting section including CNC flame cutting section & CNC Plasma cutting
section.
c) Press section (400T and 800T, Brake press).
d) Shearing M/c section.

21
8.2 ASSEMBLY AND WELDING SECTION, BAY -2

It has the following sections:

a) Assembly and welding section for large size units up to 75 tons.

b) Heat treatment section.
c) Shot blasting and cleaning section.

8.3 BAY -3

It has the following sections:

a) Assembly and welding sections of small size units unto 10 tons

b) Pipe sections.

8.4 BAY -4

It has the following sections:

a) MACHINE SECTION: It is designed for machining parts and units during

fabrication stage. This section supplies small parts and units of Steam turbine,
generators, hydro-turbine etc. The unique machines viz. CNC multi spindle drilling
machines and Horizontal ram borer are installed to help in machining of various
components like drilling of tube plates of different types apart from machining of
big assemblies such as front wall, casing, water boxes etc.
b) DIAPHRAGM SECTION: Welded diaphragms of steam turbines are assembled,
welded and stress relieved in this section.

22
c) COOLERS SECTION: In this section tubes of coolers are cut to the required size,
then turned and thereafter winding and soldering of spirals on tubes is carried out by
automatic machines. These are then assembled to form coolers which are then
assembled and hydraulically tested.
 24

9. MANUFACTURING PROCESSES

Manufacturing starts with Preparation of individual parts before assembly, in Bay -1.

a) The metal is first marked and cut by the following machines:-

- Guillotine Shearing machine for cutting and trimming steel sheets and plates up to

25mm thick with straight contours.

- Stationary and portable Oxy-acetylene cutting machines for cutting machines

for cutting parts out of steel plates.

- A unique Flame cutting machine is used for cutting steel plates by CNC

programming.

- CNC Plasma cutting M/c for cutting S.S & higher alloys.

- Combination punch, shear and bar cutters, circular saws and bar shears are used for

cutting angles, shapes, flats and rods.

b) Straightening Rollers are used for straightening plates and large sized blanks and a

160 ton friction press for straightening small sized blanks. A roll bending machine is

used for straightening and bending rolled beams and angles.

c) Hydraulic bending press of 800 ton and 400 ton and a 250 ton friction press are

used for cold and hot bending from rolled sheets and shapes. Parts to bend are pre

heated in a 700 KW electric furnace, when ever needed.

d) Finished parts are inspected at the working place.

After Preparation is complete the next step is Assembly and Welding in Bay -2 and 3 is as
follows:

24
 a) Components of units are assembled and tack welded for subsequent welding as per
drawing and instructions on process cards.
b) Manual arc welding is employed in restricted and inaccessible places or where semi-
automatic or automatic welding is not possible or has not been established.
c) Semi-Automatic submerged arc welding, GTAW and Argon Carbon-dioxide
Shielded arc welding are also used for increased productivity and better quality.

All assembly work is carried out on bed plates. Small size structures are welded with
the help of manipulators. Welding of high pressure cylinders of steam turbines is carried
out after preliminary heating up to 250° C. Heat treatment is carried out in electric furnaces
of bogie hearth, bell and pit types after welding is completed. In multi layer welding, the
roots of seams are gouged and then cleaned by mechanical means.

All assembly and welding sections have connections for compressed air, oxygen &
acetylene as well Argon carbon-dioxide mixture and water for semi automatic welding.
Weld quality inspection is adopted in accordance with the relevant specifications.
Inspection of weld quality and flaw detection is carried out by means of X-ray machines,
gamma-grapy machines of cobalt and iridium isotopes and ultrasonic flaw detectors.

Pressure vessels that are boilers, heaters, condensers and coolers undergo hydraulic
tests on special test beds meant for hydraulic testing. Kerosene leakage test is also done in
case of thin walled vessels.

Process being followed in pipe section is mentioned below:

a) Pipes with diameter of 10-60 mm and 38-108 mm are cut on pipe cuttingmachines
and oxy-acetylene cutters.
b) Cold bending of pipes is carried out on a pipe bending machine. Bending of
carbon and alloy steel pipes of 114 mm dia. and above is performed by heating
them in electric furnaces and then by hot bending.

c) Facing of pipes and beveling for welding is carried out on a horizontal boring
machine with portable type pipe chamfering machine.
d) For assembly and welding of pipes bed plates and manipulators are used.
e) Heat treatment of pipes is done in electric furnace mentioned earlier.
f) Surface cleaning is done manually or by shot blasting.
25
 Pipe assemblies are dimensionally checked and quality of welds is tested by Xray
and Gamma grapy.

Process being followed in machining section is as follows:

a) Casting, forging, rolled section and welded structures are delivered to

sections where assembly and welding are done in accordance with
specifications set forth in drawings.
b) Pre weld machining for large sized parts for steam turbines and hydro
turbines are carried out in block-3.
c) Provision is made for the application of highly productive cementedcarbide
tipped cutting tools, high speed cutting with maximum utilization with machine
tool capacity and rapid section locating and clamping fixture.
Process being followed in painting section is as follows:

a) Painting materials used and painting processes adopted, conform to

thestandards for tropical climates.
b) Owing to different operating conditions and decoration requirements of units
and parts of turbines and electrical machines, different processes for painting
are adopted.
c) Some components and units undergo only prime coating in the steel structure
section, with subsequent painting in the painting section of the machine and
assembly section.

10. CONCLUSION

Gone through rigorous one month training under the guidance of capable engineers
and workers of BHEL Haridwar in Block-2 “HEAVY FABRICATION” headed by
Senior Engineer of departmentMR.DEEPESH SINGH situated inRanipur, Haridwar,
Uttarakhand.

The training was specified under the Heavy Fabrication Department. I came to
know about the basic grinding, scaling and machining processes which were shown on
heavy to medium machines. Duty lathes were planted in the same line where the specified
work was undertaken.

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 The training brought to my knowledge the various machining and fabrication
processes done not only in the manufacturing of cams but also in other iron casted products.

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