internship report- steel mills

SYED ZOHAIB AHMED ME-45 NED University of Engineering and Technology

INTERNSHIP REPORT Pakistan Steel Mill - Summer 2015

INDEX

1

ASGN ....................................................................................................................................................................... 3

Compressor House .................................................................................................................................................. 3

Reciprocating Type Compressor (2 Units) .......................................................................................................... 3

Centrifugal Type Compressor (4 Units) ............................................................................................................... 3

Operating parameters ................................................................................................................................... 4

Gas Cleaning ........................................................................................................................................................... 5

Scrubber ............................................................................................................................................................. 5

Venturi ................................................................................................................................................................ 5

Throttle Group .................................................................................................................................................... 5

Drop Catcher ...................................................................................................................................................... 5

Electro-Filter ....................................................................................................................................................... 5

Refrigeration Plant ................................................................................................................................................. 7

Evaporator: ......................................................................................................................................................... 8

Absorber ............................................................................................................................................................. 8

Generator ........................................................................................................................................................... 8

Pumps ................................................................................................................................................................. 8

Ventilation .............................................................................................................................................................. 9

Process ............................................................................................................................................................... 9

CO2 Shop ............................................................................................................................................................... 10

Process ............................................................................................................................................................. 10

PERS-M ................................................................................................................................................................. 11

Pumps: .............................................................................................................................................................. 11

Boilers: .............................................................................................................................................................. 11

1. Water tube boiler ................................................................................................................................ 12

2. Fire tube boiler. ................................................................................................................................... 12

Turbine: ............................................................................................................................................................ 12

Hard Bearing Balancing Machine: .................................................................................................................... 12

Impeller: ........................................................................................................................................................... 12

1. Open .................................................................................................................................................... 13

2. Semi-open............................................................................................................................................ 13

3. closed .................................................................................................................................................. 13

MRHT .................................................................................................................................................................... 14

Turning: ............................................................................................................................................................ 14

Milling: ............................................................................................................................................................. 14

Heat treatment:................................................................................................................................................ 15

a. Annealing ............................................................................................................................................ 15

INDEX

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b. Normalizing ......................................................................................................................................... 15

c. Quenching ........................................................................................................................................... 15

d. Tempering ........................................................................................................................................... 16

Surface Hardening: ........................................................................................................................................... 16

F&F ........................................................................................................................................................................ 17

Forging: ............................................................................................................................................................ 17

a. Cold Forging ........................................................................................................................................ 18

b. Hot forging .......................................................................................................................................... 18

Types of Presses: .............................................................................................................................................. 18

a. Hydraulic presses ................................................................................................................................. 18

b. Mechanical presses ............................................................................................................................. 19

Welding: ........................................................................................................................................................... 19

a. Arc welding .......................................................................................................................................... 19

b. Oxy-acetylene welding ........................................................................................................................ 19

c. Spot welding ........................................................................................................................................ 19

Closing Remarks .................................................................................................................................................... 20

ASGN Compressor House 13-july-2015 to 17-july-2015

Instructor: Mr.Akram

3

ASGN Compressor House

The compressor house at Pakistan steel mills is used to compressor atmospheric air to be used in different parts

of the plant. It is supplied using a central system of pipes that lead to different parts of the plant. The advantage

of using a central compressing house is to yield efficiency in compressing and to main a high level of standard of

quality throughout the plant. Another advantage of this is that abundant quantity of compressed air is available

at disposal and can be utilized whenever required.

The Compressor House consists of two types of compressor;

1. Reciprocating Type

2. Centrifugal Type

RECIPROCATING TYPE COMPRESSOR (2 UNITS) The reciprocating type compressor is double action

compressor i.e. it delivers compress air in both forward and

reverse stroke. The compressor units consists of two sizes of

bores;

1. 630 mm

2. 370 mm

The compressor has the capacity to provide a flow of 6000

m3/hr. of air at 7 kg/cm2. They are electrically powered and

are supplied by 6.3kV 3-phase line mains. The air is inter-cooled after every stage of compression in heat

exchangers and is end-cooled before being released in to the system using forcing gate valves. The oil used is

common engine oil because the working of the compressor is similar to that of an engine. To maintain the safety

of such valuable machine and the safety of workers working near the compressor, surge valves are installed

which release excess air out of the system.

They are used as an auxiliary, i.e. if the centrifugal compressor fails then the reciprocating compressor are used

to maintain the demand.

CENTRIFUGAL TYPE COMPRESSOR (4 UNITS) Centrifugal compressor are the main working horse of the

compressor house. They are 6 stage type, i.e. they increase

the pressure of the air in 6 successive steps. The

compressor has the capacity to provide 15000 m3/hr. of air

@ terminal pressure of 7 kg/cm2. The air intake is filtered

and cleaned in separate units. The air is cooled in

Intercoolers after every 3 stages of compression. To

reduce the temperature from 170 C0 to 70 C0.

They are prime mover for the compressor is a 3-phase 1.3

MW motor which is supplied electricity @ 11kV. The

motor runs at 3000 rpm but due to a constant mesh gear box the shaft of the compressor rotates at 10300 rpm.

The compressor is held in place using two bearings, i.e. thrust and radial bearing. Thrust bearing is used because

the compressor has the tendency to move towards the suction side. Pressure gauges are installed in the

lubrication oil lines of the bearing that indicate the restriction to the flow of oil which indicate how much the

compressor has moved. The compressor and the gear box is lubricated using turbo oil which is less viscous then

normal lubricating oil due to high speed operating conditions. The oil is fed into the system @ 210 Lt/hr. The air

ASGN Compressor House 13-july-2015 to 17-july-2015

Instructor: Mr.Akram

4

is inter-cooled after every stage of compression in heat exchangers and is end-cooled before being released in

to the system using forcing gate valves. To maintain the safety of such valuable machine and the safety of

workers working near the compressor, surge valves are installed which release excess air out of the system.

Operating parameters of this facility are as follow:

Centrifugal Type Compressor

1. Capacity 15000 m3/hr.

2. Terminal pressure 5-6 kg/cm2

3. Air temp. before cooler 170 C0

4. Air temp. after cooler 70 C0

5. Cooling water flow 200 m3/hr.

6. Pressure of supply water 1.5-3 kg/cm2

7. Pressure of water outlet 1.5-2 kg/cm2

8. Temp. of supply water 20-30 C0

9. Temp. of water outlet 30=35 C0

Reciprocating Type Compressor

1. Capacity 6000 m3/hr.

2. First stage delivery pressure 1.8-2.4 kg/cm2

3. Second stage delivery pressure 5-6 kg/cm2

4. Air temp. before cooler 170 C0

5. Air temp. after cooler 70 C0

6. Cooling water flow 30 m3/hr.

7. Pressure of supply water 1.5-3 kg/cm2

8. Temp. of supply water 25-30 C0

ASGN Gas Cleaning 13-july-2015 to 17-july-2015

Instructor: Mr. Sartaj

5

Gas Cleaning

Gas cleaning plant of Pakistan Steel Mills is used to clean the gas that comes out from the blast furnace (BF 1 &

2). The sole purpose of the facility is to utilize the by-product of the iron making process, so as to conserve

energy, increase efficiency and to protect the environment because the “Raw BF Gas” contains very toxic gases,

one of which is Carbon Monoxide (23%), which is an Odorless, Colorless gas that is very poisonous and should

be handled with extreme caution. The workers in the facility use respirators to work with such substances.

The process includes 4 stages/machine to clean the gas;

1. Scrubber

2. Venturi

3. Throttle Group

4. Drop Catcher/ Electro-Filter

SCRUBBER The Scrubber is a large cylindrical vertical vessel having a

circumference of 8 meters. It contains within itself 12 Spray

Nozzles or Showers, which spray cold water on to the gas in two

stages at a discharge pressure of 8kg/cm2. The raw gas enters

the scrubber from the bottom and exits from the top. The dust

and iron particle are then removed from the bottom of the

scrubber, using gravity and internal pressure.

VENTURI The venturi is used to suddenly drop the pressure (0.3 to 0.6

kg/cm2) and increase it velocity as it passes through the throat of the venturi. This increased velocity of the gas

is used to generate a cyclone inside the body of the venturi. The particles floating in the gas settle to bottom

due to cyclone effect within the venturi.

THROTTLE GROUP Throttle group is a system of overlapping plates that are used to regulate the pressure of the gas as it enters the

final cleaning stage. It achieves this by a creating restriction to the flow of the gas. it contains 4 pipes of diameter,

2 0f which 750mm and rest are 450 and 100 each The raw gas hits these restrictions and eventually creates are

drop in the dynamic pressure of the gas.

DROP CATCHER As the name implies, drop catcher is used to remove the moisture from the gas, because high moisture content

is not desirable in the production of iron, because it will behave as an oxidizing agent promotion oxidation in the

alloy resulting in a weaker iron-alloy. It achieves this by using a similar construction as that of the throttle group.

The gas as it moves across the edges of these blades, water moisture gets condense on to these which eventually

drop to the bottom of the drop catcher where it is excreted. The drop catch is when the gas is at high operating

pressure (1.5-2 kg/cm2).

ELECTRO-FILTER Electro-Filter uses electric filed to remove the iron particles and dust from the gas. High current is passed through

the conductor inside the EF that causes it to behave like a magnet. The ionized and magnetic iron and dust

particles get attracted to these magnet and eventually gets removed. Water is continuously being sprayed on to

these magnet to remove foreign particles and finally they are flushed after the process.

EF is only used when the plant is running at low operating pressure (0.8-1.5 kg/cm2).

The total facility contains two of such units to ensure uninterrupted operations and improve redundancy. The

Major users of the gas are BFs and TPP. The excess gas is burnt in the gas burners

The operating parameters of the facility are as follow:

ASGN Gas Cleaning 13-july-2015 to 17-july-2015

Instructor: Mr. Sartaj

6

Temperature

1. Raw BF gas 300-400 C0

2. Clean BF gas 35-40 C0

3. Natural gas burners 900-1000 C0

4. Water lines 30-35 C0

5. Scrubber Sludge 45-70 C0

Pressure

1. Raw BF gas (high) 1.5-2 kg/cm2

2. Raw BF gas (low) 0.8-1.5 kg/cm2

3. Clean BF gas .7-1.2 kg/cm2

4. Circulating Water 7.5-8 kg/cm2

5. Clean Water 6-6.5 kg/cm2

6. Venturi Throat .3-.6 kg/cm2

Water Consumption

1. Scrubber (1 line) 630 m3/hr.

2. Venturies 120 m3/hr.

3. Throttle group 80 m3/hr.

4. E Filter (Continuous) 50 m3/hr.

5. E Filter (Flushing) 180 m3/hr.

ASGN Refrigeration Plant 13-july-2015 to 17-july-2015

Instructor: Mr. Mukhtar

7

Refrigeration Plant

Pakistan Steel Mills also houses a Absorption Refrigeration plant. The main purpose of this plant is to provide

chilled water @ 7 C0 to facilitate the production of steel. Furthermore it is also used for HVACR purposes in OPCC,

Process labs and others facilities of the plant.

The Refrigeration plant is located in the vicinity of the Thermal power plant and houses;

1. Lithium Bromide Absorption Chillers 3 units (2 Operational, 1 Standby)

2. Sea water booster pumps 2 units

3. Chilled water feed pumps 3 units (1 per chiller)

The plant has the capacity to provide 432 m3/hr. of water @ 7 C0 with a heat transfer rate of 3154000 kcal/hr.

per chiller. Sea and fresh water are both used for heat dissipation purpose (845 m3/hr.)

In a water-lithium bromide vapor absorption refrigeration system, water (SG <1 – 1/ 1750 kg) is used as the

refrigerant while lithium bromide (Li Br/4280 kg) is used as the absorbent. In the absorber, the lithium bromide

absorbs the water refrigerant, creating a solution of water and lithium bromide. This solution is pumped by the

pump to the generator where the solution is heated. The water refrigerant gets vaporized and moves to the

ASGN Refrigeration Plant 13-july-2015 to 17-july-2015

Instructor: Mr. Mukhtar

8

condenser where it is cooled while the lithium bromide flows back to the absorber where it further absorbs

water coming from the evaporator.

EVAPORATOR: Water as the refrigerant enters the evaporator at a very low pressure and temperature. Since very low pressure

is maintained inside the evaporator the water exists in a partial liquid state and partial vapor state. This water

refrigerant absorbs the heat from the substance to be chilled and gets fully evaporated. It then enters the

absorber.

ABSORBER A concentrated solution of lithium bromide is available in the absorber. Since water is highly soluble in lithium

bromide, solution of water-lithium bromide is formed. This solution is pumped to the generator.

GENERATOR Heat is supplied to the refrigerant water and absorbent lithium bromide solution in the generator from the

steam or hot water. The water becomes vaporized and moves to the condenser, where it gets cooled. As water

refrigerant moves further in the refrigeration piping and though nozzles, its pressure is reduced along with the

temperature. This water refrigerant then enters the evaporator where it produces the cooling effect. This cycle

is repeated continuously. Lithium bromide on the other hand, leaves the generator and re-enters the absorber

for absorbing water refrigerant.

As seen in the image above, the condenser water is used to cool the water refrigerant in the condenser and the

water-Li Br solution in the absorber. Steam is used for heating water-Li Br solution in the generator. To change

the capacity of this water-Li Br absorption refrigeration system the concentration of Li Br can be changed.

PUMPS Two types of pumps are used in this facility;

1. Booster pump Centrifugal type 130 kW 900rpm

2. Feed pumps Centrifugal type 220kW 1700rpm

The main consumer of chilled water are OPCC, Process labs, IMD, SMD, Sintering, CO2 shop, COBP and Network

ASGN Ventilation 13-july-2015 to 17-july-2015

Instructor: Mr. Iqbal

9

Ventilation

The ventilation department of Pakistan Steel Mills comes under the supervision of ASGN, the facility is

responsible for maintaining HVAC for OPCC, Process lab.

It uses a fairly standard system for chilled water based system. The chilled water passes through a set of cooling

tubes, the warm air is cooled by these cooling coils and the moisture they carry is condensed on to these coils.

This results in reduced ambient air temperatures and humidity.

PROCESS The outside air is first filtered using an oil

(PSO T46/GG) based filter. The fins are

dumped in the oil sump carrying around

300 liters of oil. Using mechanical

assembly, the fins are constantly being

moved perpendicular to the flow of air,

the dust and other air borne particles stick

to these fins which are later removed

using mechanical scrubbing.

After that there is an arrangement of 3

cooling coils that have a heat conduction

capacity of 169000 or 173000 Kcal depending on the unit. They use water from the refrigeration plant, the supply

water feed is maintained at around 10 C0 and 2.5 kg/cm2 and exits the coils at 17 C0 and 1 kg/cm2.

After which there is an arrangement of spry nozzles which is used of spray water, in case the refrigeration plant

is out of order. The system also have the capacity to heat the air, which is seldom required in Karachi but none

the less it is present incase needed. It uses water from TPP to heat the air.

The air is forced into the system using centrifugal blower system, operating at 765 rpm, rated @ 17 kW. The

duct is 800X800 mm in dimension, which gradually reduces as altitude increases. Finally exhauster are placed on

the roof of the facility, for ventilation purposes if the HVAC system is not being operated.

ASGN CO2 Shop 13-july-2015 to 17-july-2015

Instructor: Moeed Raza/ Nazar Hussain

10

CO2 Shop

The primary purpose of this shop is to produce CO2 gas used in the process of die casting, furthermore they

produce it for fire extinguishing, gas isolation, welding and to produce dry-ice. They also refill the gas cylinder

and hydraulically test the cylinders to ensure safety.

PROCESS The process for producing CO2 using absorption in MEA (Monoethanolamine) solution usually starts with

production of flue gases. But instead of recovering CO2 from blast furnace or coke oven gas, fresh natural gas is

burnt in the boilers of the facility. The boilers have the capacity to produce 1ton/hr. of steam @ 6kg/cm2 and @

a temperature of 174.6 C0 while consuming 39 m3 /hr. of Natural gas. The steam is later used to facilitate CO2

production. Boiler feed water is first filtered and tailored to meet the specification, to achieve this Kasonite

filters and sodium sulphide filters are used to remove salts and hardness from the water after which it is stored

in a feed water tank. Reciprocating feed water pumps (16 kg/cm2) are used to deliver water into the boiler

because the internal pressure of the boiler is very high and to sustain an inward flow, higher pressures are

required.

The flue gases from the boiler is passed through a series of stations which using post-combustion CO2 capture

using MEA as an absorbent, capture high quality CO2 which is then cleaned, filtered, cooled and then compressed

and filled in cylinders, to be used by its consumers. The reagent is regenerated and fed back into the system, the

steam generated in the boiler is used in the process of making the gas during regeneration of MEA. The process

is efficient and cost effective and is a proven industrial standard to produce high grade CO2 gas.

CMD PERS-M 20-july-2015 to 24-july-2015

Instructor: Manzoor Hussain

11

PERS-M

PERS-M stands for Power Equipment Repair Shop, the sole purpose of this facility is to repair and maintain Power

equipment located throughout Pakistan Steel Mills. They are highly skilled and have great technical prospect.

They facility have the technical and spatial ability to produce and maintain complex mechanical equipment

including:

1. Pumps

2. Compressors

3. Turbines

4. Impellers

5. Boiler

6. HVAC system

7. Bearings

The facility also includes a Hard Bearing Balancing Machine, Shearing Machine, Punches, Welding Stations, Sheet

Rollers and other Manufacturing facilities.

A brief description of such equipment is given below:

PUMPS: A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action. Pumps can

be classified into three major groups according to the method they use to move the fluid: direct lift,

displacement, and gravity pumps.

Pumps operate by some mechanism (typically reciprocating or rotary), and consume energy to perform

mechanical work by moving the fluid. Pumps operate via many energy sources, including manual operation,

electricity, engines, or wind power, come in many sizes, from microscopic for use in medical applications to large

industrial pumps.

There are several types of Pumps:

1. Rotary gear pump

2. Piston pump

3. Diaphragm pump

4. Screw pump

5. Gear pump

6. Hydraulic pump

7. Rotary vane pump

8. RotoDynamic Pumps

9. Plunger Pumps

10. Radial flow pumps

11. Axial flow pumps

12. Mixed flow pumps

BOILERS: A boiler is a closed vessel in which water or other fluid is heated. The fluid does not necessarily boil. The heated

or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating,

central heating, boiler-based power generation, cooking, and sanitation. The source of heat for a boiler is

combustion of any of several fuels, such as wood, coal, oil, or natural gas. Electric steam boilers use resistance-

or immersion-type heating elements. Nuclear fission is also used as a heat source for generating steam.



12

There are mainly two types of boiler

1. Water tube boiler

2. Fire tube boiler.

In fire tube boiler, there are numbers of tubes through which hot gases are passed and water surrounds these

tubes.

Water tube boiler is reverse of the fire tube boiler. In water tube boiler the water is heated inside tubes and hot

gasses surround these tubes.

TURBINE: A turbine is a rotary mechanical device that extracts energy from a fluid

flow and converts it into useful work. A turbine is a turbomachine with at

least one moving part called a rotor assembly, which is a shaft or drum with

blades attached. Moving fluid acts on the blades so that they move and

impart rotational energy to the rotor.

HARD BEARING BALANCING MACHINE: A balancing machine is a measuring tool used for balancing rotating

machine parts such as rotors for electric motors, fans, turbines,

disc brakes, disc drives, propellers and pumps. The machine usually

consists of two rigid pedestals, with suspension and bearings on

top supporting a mounting platform. The unit under test is bolted

to the platform and is rotated either with a belt-, air-, or end-drive.

As the part is rotated, the vibration in the suspension is detected

with sensors and that information is used to determine the

amount of unbalance in the part. Along with phase information,

the machine can determine how much and where to add weights

to balance the part. In hard bearing type, balancing is done at a

frequency lower than the resonant frequency of the rotor.

IMPELLER: An impeller is a rotating component of a centrifugal pump, usually made of iron, steel, bronze, brass, aluminum

or plastic, which transfers energy from the motor that drives the pump to the fluid being pumped by accelerating

the fluid outwards from the center of rotation. The velocity achieved by the impeller transfers into pressure



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when the outward movement of the fluid is confined by the pump casing. Impellers are usually short cylinders

with an open inlet (called an eye) to accept incoming fluid, vanes to push the fluid radially, and a splined, keyed

or threaded bore to accept a drive-shaft.

The impeller made out of cast material in many cases may be called rotor, also. It is cheaper to cast the radial

impeller right in the support it is fitted on, which is put in motion by the gearbox from an electric motor,

combustion engine or by steam driven turbine. The rotor usually names both the spindle and the impeller when

they are mounted by bolts.

There are three types of impeller:

1. Open

2. Semi-open

3. closed

CMD MRHT 27-july-2015 to 31-july-2015

Instructor: Abdul Khalique

14

MRHT

MRHT stands for Mechanical Repair and Heat Treatment, as the name implies, it is used to manufacture and

repair parts of machine to keep them in working order. The shop is more like a production facility rather than a

repair shop. The staff is highly technical and machine tools provide a complete aid in manufacturing or repairing

any part so ever desired. The processes involoved in repairing any equipment may involve all or few of the

following production techniques:

1. Turning

2. Milling

3. Grinding

4. Drilling

5. Shaping

6. Cutting

7. Plaining

8. Heat treatment

9. Surface hardening

10. Brazing

11. Welding

12. Assembly

A basic detail of the above processes are mentioned below:

TURNING: Turning is a form of machining, a material removal process, which is

used to create rotational parts by cutting away unwanted material.

The turning process requires a turning machine or lathe, work piece,

fixture, and cutting tool. The work piece is a piece of pre-shaped

material that is secured to the fixture, which itself is attached to the

turning machine, and allowed to rotate at high speeds. The cutter is

typically a single-point cutting tool that is also secured in the

machine, although some operations make use of multi-point tools.

The cutting tool feeds into the rotating work piece and cuts away

material in the form of small chips to create the desired shape.

Turning is used to produce rotational, typically axi-symmetric, parts

that have many features, such as holes, grooves, threads, tapers,

various diameter steps, and even contoured surfaces. Parts that are

fabricated completely through turning often include components that are used in limited quantities, perhaps for

prototypes, such as custom designed shafts and fasteners. Turning is also commonly used as a secondary process

to add or refine features on parts that were manufactured using a different process. Due to the high tolerances

and surface finishes that turning can offer, it is ideal for adding precision rotational features to a part whose

basic shape has already been formed.

MILLING: Milling is the most common form of machining, a material removal process, which can create a variety of

features on a part by cutting away the unwanted material. The milling process requires a milling machine, work

piece, fixture, and cutter. The work piece is a piece of pre-shaped material that is secured to the fixture, which

itself is attached to a platform inside the milling machine. The cutter is a cutting tool with sharp teeth that is also



15

secured in the milling machine and rotates at high speeds. By feeding the work piece into the rotating cutter,

material is cut away from this work piece in the form of small chips to create the desired shape.

Milling is typically used to produce parts that are not axially

symmetric and have many features, such as holes, slots, pockets,

and even three dimensional surface contours. Parts that are

fabricated completely through milling often include components

that are used in limited quantities, perhaps for prototypes, such as

custom designed fasteners or brackets. Another application of

milling is the fabrication of tooling for other processes. For

example, three-dimensional molds are typically milled. Milling is

also commonly used as a secondary process to add or refine

features on parts that were manufactured using a different

process. Due to the high tolerances and surface finishes that milling

can offer, it is ideal for adding precision features to a part whose

basic shape has already been formed.

HEAT TREATMENT: Heat treating is a group of industrial and metalworking processes

used to alter the physical, and sometimes chemical, properties of a material. The most common application is

metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat

treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve a desired result

such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening,

precipitation strengthening, tempering, normalizing and quenching. It is noteworthy that while the term heat

treatment applies only to processes where the heating and cooling are done for the specific purpose of altering

properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such

as hot forming or welding.

a. Annealing Annealing is a rather generalized term. Annealing consists of heating a metal to a specific temperature

and then cooling at a rate that will produce a refined microstructure. The rate of cooling is generally

slow. Annealing is most often used to soften a metal for cold working, to improve machinability, or to

enhance properties like electrical conductivity.

b. Normalizing Normalizing is a technique used to provide uniformity in grain size and composition throughout an alloy.

The term is often used for ferrous alloys that have been austenitized and then cooled in open air.

Normalizing not only produces pearlite, but also sometimes martensitic, which gives harder and

stronger steel, but with less ductility for the same composition than full annealing.

c. Quenching Quenching is a process of cooling a metal at a rapid rate. This is most often done to produce a

martensite transformation. In ferrous alloys, this will often produce a harder metal, while non-ferrous

alloys will usually become softer than normal. To harden by quenching, a metal (usually steel or cast

iron) must be heated above the upper critical temperature and then quickly cooled. Depending on the

alloy and other considerations (such as concern for maximum hardness vs. cracking and distortion),

cooling may be done with forced air or other gases, (such as nitrogen). Liquids may be used, due to

their better thermal conductivity, such as oil, water, a polymer dissolved in water, or a brine.



16

d. Tempering Untempered martensitic steel, while very hard, is too brittle to be useful for most applications. A

method for alleviating this problem is called tempering. Most applications require that quenched parts

be tempered. Tempering consists of heating steel below the lower critical temperature, to impart some

toughness. Higher tempering temperatures are sometimes used to impart further ductility, although

some yield strength is lost.

SURFACE HARDENING: Case-hardening or surface hardening is the process of hardening the surface of a metal object while allowing the

metal deeper underneath to remain soft, thus forming a thin layer of harder metal (called the "case") at the

surface. For iron or steel with low carbon content, which has poor to no hardenability of its own, the case-

hardening process involves infusing additional carbon into the case. Case-hardening is usually done after the

part has been formed into its final shape, but can also be done to increase the hardening element content of

bars to be used in a pattern welding or similar process

Common techniques used are:

1. Nitriding

2. Cyaniding

3. Carbonitriding

4. Ferritic nitrocarburizing

5. Flame and induction hardening

CMD F&F 3-August-2015 to 7-August-2015

Instructor: Muzaffar Mehmood

17

F&F

F&F stands for Forging and Fabrication. The facility is used to produce parts that can be produced by forging

operation or from the fabrication of sheet metal. The facility is quite large and employs traditional forging

techniques to manufacture parts including:

1. Forging

a. Cold

b. Hot

2. Annealing

3. Blank preparation

4. Sheet rolling

5. Welding

a. Oxy-acetylene welding

b. Arc welding

c. Spot welding

6. Shearing

7. Arc cutting

The first three incorporates forging operations while the last four incorporates fabrication. These are primary

operations, actual part may incorporate others as well.

The details of the process are given below.

FORGING: Metal forging is a metal forming process that involves applying compressive forces to a work piece to deform it,

and create a desired geometric change to the material. The forging process is very important in industrial metal

manufacture, particularly in the extensive iron and steel manufacturing industry. A steel forge is often a source

of great output and productivity. Work stock is input to the forge, it may be rolled, it may also come directly

from cast ingots or continuous castings. The forge will then manufacture steel forgings of desired geometry and

specific material properties. These material properties are often greatly improved.

Metal forging, specifically, can strengthen

the material by sealing cracks and closing

empty spaces within the metal. The hot

forging process will highly reduce or

eliminate inclusions in the forged part by

breaking up impurities and redistributing

their material throughout the metal work.

However, controlling the bulk of impurities

in the metal should be a consideration of the

earlier casting process. Inclusions can cause

stress points in the manufactured product,

something to be avoided. Forging a metal

will also alter the metal's grain structure

with respect to the flow of the material

during its deformation, and like other forming processes, can be used to create favorable grain structure in a

material greatly increasing the strength of forged parts. For these reasons, metal forging manufacture gives

distinct advantages in the mechanical properties of work produced, over that of parts manufactured by other

processes such as only casting or machining.



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Metal forgings can be small parts, or weigh as much as

700,000 lbs. Products manufactured by forging in modern

industry include critical aircraft parts such as landing gear,

shafts for jet engines and turbines, structural components for

transportation equipment such as automobiles and railroads,

crankshafts, levers, gears, connecting rods, hand tools such as

chisels, rivets, screws, and bolts to name a few. The

manufacture of forging die and the other high costs of setting

up an operation make the production of small quantities of

forged parts expensive on a price per unit basis. Once set up,

however, operation costs for forging manufacture can be

relatively low, and many parts of the process may be

automated. These factors make manufacturing large quantities of metal forgings economically beneficial.

a. Cold Forging Cold forging deforms metal while it is below its recrystallization point. Cold forging is generally

preferred when the metal is already a soft metal, like aluminum. This process is usually less expensive

than hot forging and the end product requires little, if any, finishing work. Sometimes, when aluminum

is cold forged into a desired shape, it is heat treated to strengthen the piece. This is called "tempering."

b. Hot forging When a piece of metal is hot forged it must be heated significantly. The average temperatures

necessary for hot forging are:

1. Up to 1150 C0 for Steel

2. 360 to 520 C0 for Al-Alloys

3. 700 to 800 C0 for Cu-Alloys

During hot forging, the temperature reaches above the recrystallization point of the metal. This kind of

extreme heat is necessary in avoiding strain hardening of the metal during deformation. In order to

prevent the oxidation of certain metals, like super alloys, a type of hot forging called isothermal forging

is a good choice. In isothermal forging, the metal deformation occurs within a highly controlled

atmosphere, similar to that of a vacuum.

TYPES OF PRESSES: Presses are essential part of forging operation and may include;

a. Hydraulic presses Hydraulic presses are a powerful class of machine tools, they derive the energy

they deliver through hydraulic pressure. Fluid pressure, in a particular chamber,

can be increased or decreased by the use of pumps, and valves. Sometimes

devices and systems may be used to increase the capacity of the pumps in more

powerful presses. These presses can operate over a long distance and at a

constant speed. Hydraulic presses are generally slower relative to other press

machine types. This involves longer contact with the work, therefore the

cooling of the work can be an issue when hot forming a part with hydraulic

force. Hydraulic presses are capable of being the most powerful class of presses.

Some may be as large as buildings, and can deliver awesome pressure. The

largest hydraulic presses are capable of applying 75,000 tons, (150,000,000 lbs),

of force. The hydraulic press shown is being used to manufacture a metal forging. Extrusion is also a very

common use for such a press, although extrusion is often performed horizontally.



19

b. Mechanical presses Mechanical presses belong to a class of machine tools that encompass a wide range of different machine types.

Primarily, the mechanical press transforms the rotational force of a motor into a translational force vector that

performs the pressing action. Therefore, the energy in a mechanical press comes from the motor. These types

of presses are generally faster than hydraulic or screw presses, (actually the screw press may also be classified

as a mechanical press). Unlike some presses, in a mechanical press, the application of force varies in both speed

and magnitude throughout the distance of the stroke. When performing a manufacturing operation using a

mechanical press, the correct range of the stroke is essential.

Presses are chosen based on the characteristics of the manufacturing process.

Mechanical press machine tools are commonly used in metal forging

manufacture, and sheet metal working. The desired application of force will

dictate the type of machine required. Extrusion will often necessitate a more

consistent force over a longer distance. However, a mechanical press may often

be a good choice for impact extrusion, since a fast, quickly repeatable

application of force over a limited distance is what is needed for that type of

manufacturing process. The most powerful mechanical presses in modern

manufacturing industry will have a press capacity of about 12,000 tons,

(24,000,000 lbs).

They include:

1. Crank Press

2. Knuckle joint press

3. Eccentric press

4. Rack and pinion press

WELDING: Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing

fusion, which is distinct from lower temperature metal-joining techniques such as brazing and soldering, which

do not melt the base metal. In addition to melting the base metal, a filler material is often added to the joint to

form a pool of molten material (the weld pool) that cools to form a joint that can be as strong as the base

material. Pressure may also be used in conjunction with heat, or by itself, to produce a weld.

a. Arc welding These processes use a welding power supply to create and maintain an electric arc between

an electrode and the base material to melt metals at the welding point. They can use either direct (DC) or

alternating (AC) current, and consumable or non-consumable electrodes. The welding region is sometimes

protected by some type of inert or semi-inert gas, known as a shielding gas, and filler material is sometimes used

as well.

b. Oxy-acetylene welding Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the

U.S.) and oxy-fuel cutting are processes that use fuel gases and oxygen to weld and cut metals, In oxy-fuel

welding, a welding torch is used to weld metals. Welding metal results when two pieces are heated to a

temperature that produces a shared pool of molten metal. The molten pool is generally supplied with additional

metal called filler. Filler material depends upon the metals to be welded.

c. Spot welding The Resistance to the flow of current through the weld piece at the pressure point creates

heat. Enough current causes the weld piece to become plastic and eventually become molten. The pincer

pressure forges the molten material to fuse together. Continued pressure initially after the fusing stage forges

the weld into a "Weld Nugget". This process is also called Single Point Resistance Weldin

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Closing Remarks

Being an Internee at the Pakistan`s largest industrial complex has been a great learning opportunity for me. The

experiences I learnt here, will greatly affect my knowledge, analysis, and problem solving abilities.

I would personally like to thank all my instructors for the time they provided me, in their busy work routines and

for the help they gave me in producing this report. Moreover I would like to thank the human resources

department for considering my application and giving me chance to discover the internal working of the

mentioned organization.

I would like to keep a professional relation with Pakistan Steel Mills in the coming future, for the acquiring and

for the transfer of technical knowledge and skills.

_________________

Syed Zohaib Ahmed

BE Mechanical (Exp. Dec 2016)

+92-336-2142382

[email protected]

internship report- steel mills

Documents

reciprocating type compressor

centrifugal type compressor

compressor house

ned university of engineering

syed zohaib ahmed

refrigeration plant

co2 shop

operating parameters