iubat practicum report bsme main part
TRANSCRIPT
Chapter: One
Introduction
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1.1 GeneralInternship is the process of on-the-job training, which particularly beneficial for students with major in
technical courses. International University of Business Agriculture and Technology (IUBAT) provide
that glorious opportunity to their students of having an internship within their bachelor program. For
these purpose industry people are invited to IUBAT to talk about their companies and experiences,
often some technical courses are entirely conducted by them. The four month internship program is
another, possibly most effective, way of achieving industry orientation. Internship helps the students to
link-up their academic experience with industry practices. I have tried my best to combine the both
together. The company I was sent for internship is Milnars Pumps Ltd. It is one of the leading pump
Manufacture companies in Bangladesh.
1.2.1. Objectives
The main objective of the report is to show the total working procedure of manufacturing process and
testing of centrifugal and submersible pumps the related other aspects of the concept Milnars Pumps
Ltd.
1.2.2. The specific objective of this report includes
To study centrifugal pumps practically.
To study metal casting process, pattern allowance, core making and heat treatment process of
centrifugal.
To study the different type of metal casting furnace.
To study different type of machine operation of centrifugal pump.
To study testing of centrifugal & submersible pumps.
To study different types of pump assemblies.
To suggest probable solution of the identified problem.
1.3 Scope
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The internship report is concentrating on to instate and to shine the feasibility into the existing industry
and the sources are referred text and internet. It is containing in-depth study from Milnars Pumps Ltd
source considering the existing structure of the report. In this report I have only focused on the
manufacturing process of centrifugal pumps of the company, not on the overall product of the industry.
1.4 Methodology
A qualitative research method has been used to carry out this study of practicum in Milnars Pumps Ltd.
They introduced us industrial foundry work in there factory. I introduce with Induction furnace, pattern and
core making, various type of machine operations. There use sand mold casting and casting materials are
cast iron, mild steel, bronze. The information of this report has been collected from the following sources
1.5 Limitations
During Practicum in Milnars Pumps Ltd, I have got a lots of information and they are very much
cooperative and they help us a lot. This report has been prepared for only the Centrifugal Pump &
Submersible Pump. Nothing is described about the other pumps like turbine pump, reciprocating
pump, rotary pump. i focused on the manufacturing process only.
Project time was insufficient.
There was some safety problem.
Updated tools is not sufficient.
Technical term is not sufficient.
Special tools is not sufficient& some spares parts have no available.
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Chapter: Two
Company Overview
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2.1 Introduction
Milnars Pumps Limited (MPL) has a history of over four decades. It was originally founded in 1961 in
the name of KSB Pumps Company Limited as an affiliate of KSB Germany at time when the country
was just on the verge of making a breakthrough in agricultural production of food through small
localized mechanical Irrigation system. Its factory was established at Tongi, 20 Km north of Dhaka
City on an area covering about 3.50 acres. After 1972 independence of Bangladesh, the parent
company KSB Ag of Germany took direct control of the management and renamed it as KSB Pumps
Company (Bangladesh) Limited. Later in 1980, after obtaining majority of share from KSB, its
operation started under the name MILNARS PUMPS LTD. Under the new management presently,
MPL is wholly owned by AFTAB GROUP. Aftab Group is one of the leading multidisciplinary
Industrial and business house of Bangladesh. AftabGroup is involved in Banking,
Engineering/manufacturing, agro-industrial productions, garments, textile and multifarious trading
activities in Bangladesh and real-estate business in USA. The company has its own foundry in its
premises at Tongi Works. Backed-up with an on-job solid experience of more than four decades, the
MPL products are the result of forward looking techniques, modern machining and accurate &
precision tooling under the inspiring and dedicated professionalism of its 12 highly qualified engineers
and 175 skilled work personnel. Very recently, the company underwent extensive and exhaustive
program. Under the program, Induction Furnace has been installed with well-equipped laboratory for
casting of quality stainless steel (SS), other alloy steel and sherardized graphite iron (SG) products.
This modern plant is the only and first of its kind in Bangladesh and can meet the demand of casting of
different type of products of different qualitative specification required in pump valve and other
machine part/component manufacturing. MPL pumps and its other products are manufactured
according to DIN standard and to highest design meeting international quality. Every product has to
undergo comprehensive inspection and tests in company’s most modern test bed in 2002. MPL
obtained ISO9001:2000 certification for Quality Management System, as the first and only Pump and
casting industry in Bangladesh. MPL current product lines what we believe to be among the best and
finest available in this part of the world. Hundreds and thousands of MPL pumps can be seen at work
all over Bangladesh in surface and ground water irrigation projects, Hydro projects, And municipal
water supplies as well as in various industrial enterprises.
2.1.1Company Location
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Head Office
Uttara Bank Bhaban(5th Floor)
90, Motijheel Commercial Area, Dhaka-1000
Bnagladesh, G.P.O Box No. 428
Fax : 880-2-9559431, 9563319
E-mail :[email protected], [email protected]
Web : www.milnarspumps.com
Phone : 9563526,9563436,9567203
Factory Location
Aftab Complex, Cherag Ali 89-90,Tongi I/A.
Gazipur-1704
Fax : 9815549
Phone : 9802385
2.1.2 VisionThe company’s vision is to make progress possible through excellence in technology, integrity and
unsurpassed customer services. The company principles evolve around the idea of providing high 6
quality customer services with reliability and innovative practices through persistent teamwork of
responsible employees. The management of MPL strongly appreciates the diversity in the vast amount
of knowledge and experience their people bring with them to the company. They also acknowledge the
professional specialization of each company personnel and believe that there is always something one
can teach and learn from others; hence they actively encourage everyone to work collaboratively
together.
2.1.3 Mission
We manufacture and market a selected range of standard and engineered pumps and castings of world
class quality. Our efforts are directed to have delighted customers in the water, sewage, oil, energy,
and industry and building services sectors. In line with the Group strategy, we are committed to
develop into a center of excellence in water application pumps and be a strong regional player. We
want to market valves, complete system solutions and foundry products including patterns for captive,
automotive and other industries. We will develop a world class human resource with highly motivated
and empowered employees.
2.1.4 Social commitment
MPL places particular value on social welfare and environmental protection. Working under the name
of MPL Care, our Corporate Social Responsibility program is focused to provide a sustainable
infrastructure and basic amenities to underprivileged students at schools in the rural areas of Pakistan.
Our commitment towards our Country shines through the efforts we put in our business and our
corporate social responsibility.
2.1.5MPL Code of Conduct
The Code of Conduct constitutes the basis of compliance activities at MPL. It describes the key legal
and business policy principles that we use in our relationships with customers, suppliers and other
business partners as well as our internal cooperation. It also determines our conduct on financial
markets and in the various countries in which we work. The Code aims to support employees in their
day-to-day work
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2.1.6 Management structure
Figure 1: Management structure
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General ManagerAsistant Manager ProjectAsistant Manager FoundrySupervisorManager PalaningSr. Foremen(Quality Control)Inspector (Quality Control)Draft manStore officerStore clerkSub Asst. EngineerPlaning AssistantJr. Store officerStore clerkAsistant Manager ProductionProduction CodinatorForemen ProductionForemen MaintainsAsistant Manager PersonalTime KeeperProduction Engineer
2.2 Company product profile and their detail
2.2.1 Product Profile:
a. ETA 40-20
b. ETA 150-26
1. Submersible Pump: 2 Models
a. Sub-B7B
b. Sub-B12B
2. Turbine Pump
3. High Pressure Multistage Pump: 2 Models
a. MOVI-30
b. MOVI-40
4. Domestic Pump
5. Sluice Valve
6. N/Return Valve
7. Jaw Plate9
2.2.2 Product Details of MPL
a. Centrifugal pump
Materials of construction
Volute casing, Impeller, Suction cover, Bearing stool etc. are made of Cast Iron(Bronze or SS for
special requirement)Shaft made from cold drawn carbon steel(SS for special requirement)
Specifications
Size NW 40 to 250 mm
Capacity Q Up to 550 m³/hr
Total Head H Up to 100 meter
Discharge Pressure P Up to 8.50 bar
Temperature T -10 to 130° C
Speed N Up to 2900 rpm
Applications
Organic and Inorganic Liquids.
Drugs and Pharmaceuticals
Refineries, Fertilizer Plant, Petrochemical and Chemical.
Process Industries.
Dyes and Intermediates.
Agricultural undertakings.
General water supply duties for Municipal.
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b. Sluice Valves
Materials of construction
The selection of the correct material of construction for valves body from the wide choice
available is government by the pressure, the temperature and the nature of the fluid flowing
through the valves.
Standard execution
Body, dome, wedge gate, Stuffing box and hand wheel are of Cast Iron.
Face ring in body and on the gate are of Bronze, an alloy of high wearing qualities material
naturally developed for use in valves and fittings.
Spindle of forged bronze upto valve size NW 100 and stainless steel for NW 125, 150 & 200.
c. High pressure multistage pump
Specifications
Size NW 32 40
Capacity Q upto 42 m³/hr (0.41 cusec)
Total Head H upto 400 M (1300 ft)
Discharge Pressure P upto 40 Bar (570 psi)
Temperature T -10° To +140 °C
Speed N upto 2900 Rpm
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Applications
Irrigation, water, General water supply, Fountains, Pressure Boosting, Pumping of Boiler Feed water,
Cooling water and Hot water Circulation, Pumping of Condensates, firefighting etc.
d. Deep well Turbine Pump
Water Lubricated, vertical, Single stage or Multi stage Turbine Pump
Specifications
Well Diameter D 8″ to 20″
Delivery size NW 3″ to 8″
Bowl size A 5.5″ to 11.5″
Capacity upto 300 m³/hr
Total Head H upto 100 meter
Applications
Agricultural undertakings.
General water supply duties for Municipal.
Refineries, Fertilizer Plant, Petrochemical and Chemical.
e. Submersible Pump
Specifications
Well Diameter D 6″ To 14″
Delivery size NW 50 to 250 mm
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Capacity Q Up to3
0m³/hr
Total Head H Up to 450 meter
Speed N Up to 2900 rpm
Voltage V 360 to 440 v
Motor rating HP Up to 250
Applications
Pressure boosting.
Industrial water Supply for Trade and Industry.
Process Industries.
f. Reflex Valve
Specifications
Reflux Valve is a one way shut-off device. Flap opens in one direction automatically permitting the
flow, while reversal of flow is prevented as flap door closes under the action of gravity and back
pressure.
Applications
Agricultural undertakings.
Irrigation & drainage.
Pressure boosting.
Industrial water Supply for Trade and Industry.
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g. Domestics Pumps
Applications
Used for domestic water lifting purpose.
[Any of the above products can be made from any special material as per customer’s requirement.
Also manufacture Parts and products of special alloy steel and Iron as required by customer]
2.5 Production Capacity of Milnars Pumps Ltd.
Milnars Pumps Ltd. is involved in the assembly and manufacturing of pumps which are essentially
devices for lifting and movement or transfer of water or any other fluid. The company’s present yearly
production capacity is 20,000 Centrifugal pumps, 1,500 Deep Well Turbine Pumps, Submersible
Pumps, High Pressure Industrial Pumps and Domestic pumps of various design and capacities, MPL
also manufactures Sluice and Non-Return valves from diameter 37 mm to 200 mm sizes.
2.6 Commitment to Customer
Our success is based upon our customer focus. We listen to and connect with customer. We anticipate
their needs and make it easy for them to do business with us. We keep promises. We offer internal and
external customer value and quality services to enrich lives and enhance business success. We treat
them with dignity and respect.
2.7 Certificate and Award and Social Activities
In 2002, MPL obtained ISO9001:2000 certification for Quality Management System, as the first and
only Pump and casting industry in Bangladesh. MPL’s current product lines what we believe to be
among the best and finest available in this part of the world. Hundreds and thousands of MPL pumps
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can be seen at work all over Bangladesh in surface and ground water irrigation project, BWDB Hydro
projects, And Municipal Water Supplies as well as in various industrial enterprises.
2.8 Organizational activities analysis
2.8.1 Marketing Mix
The marketing mix is probably the most famous marketing team. Its elements are the basic, technical
components of a marketing plan. Overall sales activities are run by two departments one is Direct
Sales and other is Dealer Sales. The department runs under the very able guidance of Mr. Kader Khan
GM, Sales, whose service background and experience of man management has been a key factor for
the success of the department.
1. Products:
Centrifugal pump.
Sluice Valves.
Movi.
Deep well.
Turbine pump.
Submersible pump.
Reflux valve.
Domestic pumps.
1. Place: Country wide.
2. Price: Competitive.
3. Promotion: Competitive.
2.8.2 Analysis of products of MPL:
Strengths
A firm’s strengths are its resources and capabilities that can be used as a basis for developing a
competitive advantage.
Patents
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Strong brand names.
Cost advantages.
Specialist marketing expertise.
A new, innovative product or service and location of business.
Weaknesses
The absence of certain strengths may be viewed as a weakness. For example, each of the following
may be considered weaknesses.
Poor reputation among customers.
Lack of access to the best natural resources
Lack of access to key distribution channels
Undifferentiated products or services
Opportunities
The external environmental analysis may reveal certain new opportunities for profit and
growth.
An unfulfilled customer need.
Arrival of new technologies.
Removal of international trade barriers.
A developing market such as the internet.
Market vacated by an ineffective competitor.
Shifts in consumer tastes away from the firm’s products.
Emergence of substitute products.
Price wars with competitors.
Competitor has new, innovative product or service.
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Chapter: Three
Pump Terminology
NPSHr– NPSH required – is a function of the pump design and is the lowest value of NPSH at which
the pump can be guaranteed to operate without significant Cavitation. There is no absolute criterion for
determining what this minimum allowable NPSH should be, but pump manufacturers normally select
an arbitrary drop in total dynamic head (differential head) of 3% as the normal value for determining
NPSHr.
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NPSH – Net positive suction head – total head at pump suction branch over and above the vapour
pressure of the liquid being pumped.
NPSHa— NPSH available – is a function of the system in which the pump operates and is equal to the
absolute pressure head on the liquid surface plus the static liquid level above the pump centreline
(negative for a suction lift) minus the absolute liquid vapour pressure head at pumping temperature
minus the suction friction head losses.
Cavitation – Process in which small bubbles are formed and implode violently; occurs when
NPSHa<NPSHr.
Density (specific weight of a fluid)– Weight per unit volume, often expressed as pounds per cubic
foot or grams per cubic centimeter.
Flooded Suction – Liquid flows to pump inlet from an elevated source by means of gravity.
Flow – A measure of the liquid volume capacity of a pump. Given in gallons per minute (GPM), liters
per second and cubic meters per hour.
Head – A measure of pressure, expressed in meters for centrifugal pumps. Indicates the height of a
column of water being moved by the pump(without friction losses).
Pressure – The force exerted on the walls of a tank, pipe, etc. by a liquid. Normally measured in
pounds per square inch(psi) or kilopascals (kpa).
Prime – Charge of liquid required to begin pumping action when liquid source is lower than pump.
Held in pump by a foot valve on the intake line or by a valve or chamber within the pump.
Self/Dry Priming – Pumps that draw liquid up from below pump inlet (suction lift), as opposed to
pumps requiring flooded suction.
Specific Gravity – The ratio of the weight of a given volume of liquid to pure water. Pumping heavy
liquids (specific gravity greater than 1.0) will require more drive kilowatts.
Static Discharge Head – Maximum vertical distance (in meters) from pump to point of discharge with
no flow.
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Strainer – A device installed in the inlet of a pump to prevent foreign particles from damaging the
internal parts.
Sump – A well or pit in which liquids collect below floor level; sometimes refers to an oil or water
reservoir.
Total Head – Sum of discharge head, suction lift, and friction loss.
Viscosity – The “thickness” of a liquid or its ability to flow. Most liquids decrease in viscosity and
flow more easily as they get warmer.
Valves Bypass Valve – Internal to many pump heads that allow fluid to be r ecirculated if a given
pressure limit is exceeded.
Check Valve – Allows liquid to flow in one direction only. Generally used in discharge line to prevent
reverse flow.
Foot Valve – A type of check valve with a built-in strainer. Used at point of liquid intake to retain
liquid in system, preventing loss of prime when liquid source is lower than pump.
Relief Valve – Used at the discharge of a positive displacement pump. An adjustable, spring loaded
valve opens when a preset pressure is reached. Used to prevent excessive pressure buildup that could
damage the pump or motor.
Pump Installation Information
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Figure 1: Different types of heads
Static Head – The hydraulic pressure at a point in a fluid when the liquid is at rest.
Friction Head – The loss in pressure or energy due to frictional losses in flow.
Discharge Head – The outlet pressure of a pump in operation.
Total Head – The total pressure difference between the inlet and outlet of a pump in operation.
Suction Head – The inlet pressure of a pump when above atmospheric pressure.
Suction Lift – The inlet pressure of a pump when below atmospheric pressure.
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Chapter: Four
The Centrifugal Pump
4.1 Definition of Centrifugal Pump
A centrifugal pump is a rotodynamic pump that uses a rotating impeller to increase the velocity of a
fluid. Centrifugal pumps are commonly used to move liquids through a piping system. The fluid enters 21
the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially
outward into a diffuser or volute chamber, from where it exits into the downstream piping system.
Centrifugal pumps are used for large discharge through smaller heads.
Figure 2: A centrifugal pump
4.2 Working Mechanism of a Centrifugal PumpA centrifugal pump works by the conversion of the rotational kinetic energy, typically
From an electric motor or turbine, to an increased static fluid pressure. This action is described by
Bernoulli's principle. The rotation of the pump impeller imparts kinetic energy to the fluid as it is
drawn in from the impeller eye (centre) and is forced outward through the impeller vanes to the
periphery. As the fluid exits the impeller, the fluid kinetic energy (velocity) is then converted to (static)
pressure due to the change in area the fluid experiences in the volute section. Typically the volute
shape of the pump casing (increasing in volume), or the diffuser vanes (which serve to slow the fluid,
converting to kinetic energy in to flow work) are responsible for the energy conversion. The energy
conversion results in an increased pressure on the downstream side of the pump, causing flow.
Cavitation is the problems in the pump. It is defined as the phenomenon of formation of
vapor bubbles of a flowing liquid in a region where the pressure of the liquid falls below its
vapor pressure. Cavitation is usually divided into two classes of behavior: inertial (or transient)
Cavitation and non-inertial Cavitation. Inertial Cavitation is the process where a void or bubble in a
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liquid rapidly collapses, producing a shock wave. Such Cavitation often occurs in pumps, propellers,
impellers, and in the vascular tissues of plants. Non-inertial Cavitation is the process in which a bubble
in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic
field. Such Cavitation is often employed in ultrasonic cleaning baths and can also be observed in
pumps, propellers etc.
Figure 3: Main components of a centrifugal pump
4.3 Different Types of Centrifugal Pump
Centrifugal Pumps are classified into three general categories:
a. Axial Flow Pumps
Axial-flow pumps differ from radial-flow in that the fluid enters and exits along the same direction
parallel to the rotating shaft. The fluid is not accelerated but instead "lifted" by the action of the
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impeller. They may be likened to a propeller spinning in a length of tube. Axial-flow pumps operate at
much lower pressures and higher flow rates than radial-flow pumps.
b. Radial Flow Pumps
Often simply referred to as centrifugal pumps. The fluid enters along the axial plane, is
accelerated by the impeller and exits at right angles to the shaft (radially). Radial-flow
pumps operate at higher pressures and lower flow rates than axial and mixed-flow pumps.
Mixed-flow pumps function as a compromise between radial and axial-flow pumps. The
fluid experiences both radial acceleration and lift and exits the impeller somewhere between
0 and 90 degrees from the axial direction. As a consequence mixed-flow pumps operate at
higher pressures than axial-flow pumps while delivering higher discharges than radial-flow
pumps. The exit angle of the flow dictates the pressure head-discharge characteristic in
relation to radial and mixed-flow.
c. Mixed Flow Pumps
Mixed-flow pumps function as a compromise between radial and axial-flow pumps. The fluid
experiences both radial acceleration and lift and exits the impeller somewhere between 0 and 90
degrees from the axial direction. As a consequence mixed-flow pumps operate at higher pressures than
axial-flow pumps while delivering higher discharges than radial-flow pumps. The exit angle of the
flow dictates the pressure head-discharge characteristic in relation to radial and mixed-flow.
4.4 Different Parts of Centrifugal Pump:
1. Impeller. 2. Volute.
3. Discharge Nozzle. 4. Casing.
5. Bearings. 6. Seal.
7. Suction Nozzle. 8. Shaft.
9. Oil Ring.
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Figure 4: Different parts of a centrifugal pump
Impellers
The impeller of the centrifugal pump converts the mechanical rotation to the velocity of the liquid. The
impeller acts as the spinning wheel in the pump.
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 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 asp lined, 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 25
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.
The casting process, as mentioned above, is the primary method of impeller manufacture. Smaller size
impellers for clean water maybe cast in brass or bronze due to small section thickness of shrouds and
blades. Recently, plastic has also been introduced as casting material.
Figure 5: Impeller
Volute CasingThe volute of a centrifugal pump is the casing that receives the fluid being pumped by the impeller,
slowing down the fluid's rate of flow. A volute is a curved funnel that increases in area as it
approaches the discharge port. The volute converts kinetic energy into pressure by reducing speed
while increasing pressure, helping to balance the hydraulic pressure on the shaft of the pump. The
name "volute" is inspired by the resemblance of this kind of casing to the scroll-like part near the top
of an Ionic order column in classical, called a volute.
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Figure 6: Volute Casing
Discharge NozzleA discharge nozzle being located at the discharge opening of a flexible container being deformed by
external pressure to discharge the content. Liquid channel in the nozzle is open at all times from the
inlet on the container body side to the discharge opening and a part thereof is constituted of a gap
passage defined by a plurality of faces. The gap passage has such dimensions that the content liquid
stagnates under normal pressure due to its viscosity or surface tension and does not flow through the
gas passage easily and the content can be discharged by pressing the container body. The discharge
nozzle is provided with a function for preventing the content in the fluid channel thereof and the outer
air from flowing back into the container body when the pressing force is released.
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Figure 7: Discharge Nozzle
Break Bearing StoolBreak bearing Stool is made by cast iron. B.B Stool mainly uses for contains ball bearings, oil seal,
Lubricating oil and pump shaft. The electric motors rotating motion is past form B.B stool by pump
shaft. B.B stool fixed with base with buffer for avoid vibration. Its size depends on volute casing.
Figure 8: Break bearing stool28
Shaft SleeveA shaft sleeve is shaped like a cylindrical hollow metal tube which is mounted over the shaft, this
offers the right amount of protection during the packing. Pump shaft, most of the times, offer apt
protection from corrosion, erosion. If we talk about the standard function of the shaft sleeve, it would
be to protect the shaft from packing wear at stuffing box.
The application of the shaft sleeve is commonly in single stage pumps. The placement of both the
sealing gland and the impeller is not direct on the shaft. The sleeve is strategically placed amid the
impeller’s bore. As far as this type of assembly is concerned, sleeve remains the wearable part and the
best part is that you don’t have to spend more as compared to the shaft. The key task of the impeller
sleeves is to offer the right amount of protection to the shaft from damage. Various different functions,
which are performed by the sleeve, are given some specific names, in order to specify their function.
There is a prevention for sleeve rotation via a key; most of the times it is the impeller’s key. It is
through the sleeve that the impeller’s axial thrust is transferred to the external shaft nut. For a pump
with larger head, having an axial load on the sleeve is practical. The key advantages of the design
comprise of easiness and assembly & maintenance is hassle free. Right amount of space is offered for
a cartridge type mechanical seals and large seal chamber.
There are manufacturers which prefer the sleeve, where the sleeve’s impeller end is weaved with a
thread that matches on the shaft. Especially, for this type a key is of no use and both left & right hand
threads are being replaced. This helps in tightening the frictional hold of the packing while being on
the sleeve. For the pumps having hanging impellers, varied forms of sleeves are being put into use.
There are mechanical seals which possess a cartridge design, it may be tested for the leakage before
the pump is being actually installed. In the earlier days, a hook type sleeve used to be quite popular.
The cartridge type mechanical seals has become more and more popular, owing to which the hook type
sleeves are less preferred.
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Figure 9: Pump Shaft Sleeve
Wear ringsWear rings are sacrificial components installed on the casing and impeller to inhibit fluid from
recalculating back to suction from the discharge. They provide a renewable restriction between a
closed impeller and the casing. Wear rings are often installed on both the front and back of the
impeller. When wear rings are installed on the back of the impeller, another set of rings is installed in
the back cover.
Figure 10: Wear ring
Stuffing boxes
The stuffing box is a chamber or a housing that serves to seal the shaft where it passes through the
pump casing.
In a stuffing box, 4–6 suitable packing rings are placed and a gland (end plate) for squeezing and
pressing them down the shaft.30
The narrow passage, between the shaft and the packing housed in the stuffing box, provides a
restrictive path to the liquid, which is at a high pressure within the pump casing.
The restrictive path causes a pressure drop, prevents leakage resulting in considerable friction between
the shaft and the packing, and causes the former to heat up. It is thus good practice to tighten the gland
just enough to allow for a minimal leak through the packing. This slight leakage of the liquid acts as a
lubricant as well as a coolant. Obviously, this cannot be allowed for hazardous and toxic liquids, but
then gland packings are also not used in such applications. When pumps are handling dirty or high-
pressure liquid, lantern rings are used. These are rings with holes drilled along its circumference.
A lantern ring substitutes one of the packing rings in the stuffing box and is situated at the pump end or
midway between the packings.
Ball Bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between
the bearing races.
The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It
achieves this by using at least two races to contain the balls and transmit the loads through the balls. In
most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub
or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are
rolling they have a much lower coefficient of friction than if two flat surfaces were sliding against each
other.
Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element
bearings due to the smaller contact area between the balls and races. However, they can tolerate some
misalignment of the inner and outer races.
Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element
bearings due to the smaller contact area between the balls and races. However, they can tolerate some
misalignment of the inner and outer races.
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Figure 11: A ball bearing
GasketA gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to
prevent leakage from or into the joined objects while under compression.
Gaskets allow "less-than-perfect" mating surfaces on machine parts where they can fill irregularities.
Gaskets are commonly produced by cutting from sheet materials.
Gaskets for specific applications, such as high pressure steam systems, may contain asbestos.
However, due to health hazards associated with asbestos exposure, non-asbestos gasket materials are
used when practical.
It is usually desirable that the gasket be made from a material that is to some degree yielding such that
it is able to deform and tightly fill the space it is designed for, including any slight irregularities. A few
gaskets require an application of sealant directly to the gasket surface to function properly.
Some (piping) gaskets are made entirely of metal and rely on a seating surface to accomplish the seal;
the metal's own spring characteristics are utilized (up to but not passing, the material's yield strength).
This is typical of some "ring joints" (RTJ) or some other metal gasket systems. These joints are known
as R-con and E-con compressive type joints.
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.
Figure 12: Gaskets
Gland
A gland is a general type of stuffing box, used to seal a rotating or reciprocating shaft against a fluid.
The most common example is in the head of a tap (faucet) where the gland is usually packed with
string which has been soaked in tallow or similar grease. The gland nut allows the packing material to
be compressed to form a watertight seal and prevent water leaking up the shaft when the tap is turned
on. The gland at the rotating shaft of a centrifugal pump may be packed in a similar way and graphite
grease used to accommodate continuous operation. The linear seal around the piston rod of a double
acting steam piston is also known as a gland, particularly in marine applications. Likewise the shaft of
a hand pump or wind pump is sealed with a gland where the shaft exits the borehole.
Other types of sealed connections without moving parts are also sometimes called glands; for example,
a cable gland or fitting that connects a flexible electrical conduit to an enclosure, machine or bulkhead
facilitates assembly and prevents liquid or gas ingress
Couplings
Couplings for pumps usually fall in the category of general-purpose couplings. General-purpose
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couplings are standardized and are less sophisticated in design. The cost of such coupling is also on the
lower side.
In these couplings, the flexible element can be easily inspected and replaced. The alignment demands
are not very stringent.
4.5 Pump efficiencyWhen we speak of the efficiency of any machine, we are simply referring to how well it can convert
one form of energy to another. If one unit of energy is supplied to a machine and its output, in the
same units of measure, is one-half unit, its efficiency is 50 percent. As simple as this may seem, it can
still get a bit complex because the units used by our English system of measurement can be quite
different for each form of energy. Fortunately, the use of constants brings equivalency to these
otherwise diverse quantities. A common example of such a machine is the heat engine, which uses
energy in the form of heat to produce mechanical energy. This family includes many members, but the
internal combustion engine is one with which we are all familiar. Although this machine is an integral
part of our everyday lives, its effectiveness in converting energy is far less than we might expect.
The efficiency of the typical automobile engine is around 20 percent. To put it another way, 80 percent
of the heat energy in a gallon of gasoline does no useful work. Although gas mileage has increased
somewhat over the years, that increase has as much to do with increased mechanical efficiency as
increased engine efficiency itself. Diesel engines do a better job but still max out around 40 percent.
This increase is due, primarily, to its higher compression ratio and the fact that the fuel, under high
pressure, is injected directly into the cylinder.
Energy usage
The energy usage in a pumping installation is determined by the flow required, the height lifted
and the length and friction characteristics of the pipeline. The power required to drive a pump (
), is defined simply using SI units by:
34
where:
is the input power required (W)
is the fluid density (kg/m3)
is the standard acceleration of gravity (9.80665 m/s2)
is the energy Head added to the flow (m)
is the flow rate (m3/s)
is the efficiency of the pump plant as a decimal
The head added by the pump ( ) is a sum of the static lift, the head loss due to friction and any losses
due to valves or pipe bends all expressed in meters of fluid. Power is more commonly expressed as
kilowatts (103 W) or horsepower (multiply kilowatts by 0.746). The value for the pump efficiency
may be stated for the pump itself or as a combined efficiency of the pump and motor system.
The energy usage is determined by multiplying the power requirement by the length of time the pump
is operating.
4.6 Problems of centrifugal pumps
• Cavitation—the NPSH of the system is too low for the selected pump.
• Air leaks in suction piping—If liquid pumped is water or other non-explosive, and explosive
gas or dust is not present.
• Discharge system head too high.
Wear of the Impeller—can be worsened by suspended solids.
Corrosion inside the pump caused by the fluid properties.
Overheating due to low flow.
Leakage along rotating shaft.35
Lack of prime—centrifugal pumps must be filled (with the fluid to be pumped) in order to
operate surge.
4.7 Centrifugal pumps for solids control
An oilfield solids control system needs many centrifugal pumps to sit on or in mud tanks. The
types of centrifugal pumps used are sand pumps, submersible slurry pumps, shear pumps, and
charging pumps. They are defined for their different functions, but their working principle is the
same.
4.8 Magnetically coupled pumps
Small centrifugal pumps (e.g. for garden fountains) may be magnetically coupled to avoid leakage
of water into the motor. The motor drives a rotor carrying a pair of permanent magnets and these
drag round a second pair of permanent magnets attached to the pump impeller. There is no direct
connection between the motor shaft and the impeller so no gland is needed and, unless the casing
is broken, there is no risk of leakage.
4.9 PrimingPriming is the process in which the impeller of a centrifugal pump will get fully sub merged in liquid
without any air trap inside. This is especially required when there is a first start up. But it is advisable
to start the pump only after primping. If want to pump the vapors out of casing then you have to run
the pump at a speed equal to it design speed multiplied by the ratio of specific gravity of air to water.
(In case of pumping water) which is practically impossible. Liquid and slurry pumps can lose prime
and this will require the pump to be primed by adding liquid to the pump and inlet pipes to get the
pump started. Loss of "prime" is usually due to ingestion of air into the pump. The clearances and
displacement ratios in pumps used for liquids and other more viscous fluids cannot displace the air due
to its lower density.
A "self-priming" centrifugal pump overcomes the problem of air binding by mixing air with water to
create a fluid with pumping properties much like those of regular water. The pump then gets rid of the
air and moves water only, just like a standard centrifugal pump. It is important to understand that self-
priming pumps cannot operate without water in the casing. In order for a centrifugal pump, or self
36
priming, pump to attain its initial prime the casing must first be manually primed or filled with water.
Afterwards, unless it is run dry or drained, a sufficient amount of water should remain in the pump to
ensure quick priming the next time it is needed.
Reciprocating and rotary pumps are self-priming. This is an important consideration where a prime
cannot be maintained on the pump. Centrifugal pumps are not inherently self-priming, although some
manufacturers do specially design self-priming units. External priming sources, such as an educator or
vacuum pump can also be employed.
Figure 14: Priming
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Chapter Five
Manufacturing Process
of Centrifugal Pump
Manufacturing ProcessManufacturing process of a centrifugal pump is a combination work. Every parts of a centrifugal pump
produce individually maximum of its parts are made by casting process some are made by machine
operation. The operations are dividing by some section such as
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1. Foundry shop.
2. Machine shop.
3. Assembly Section.
4. Testing Section.
Figure 15: Machine shop of MPL
5.1 Foundry Shop
Foundry shop is the place where the metal casting is prepared by melting and pouring the molten metal
into moulds. A foundry is an operating plant which manufactures castings of metal, both ferrous and
non-ferrous. Metals are processed by melting, pouring, and casting. Iron is the most common base
element processed in a modern foundry. However, other metals, such as, aluminum, copper, tin, and
zinc, can be processed.
Foundry section can have the following processes:
Melting
Furnace
Mold making
Pouring
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Shakeout
Degating
Heat treating
Surface cleaning
Finishing
5.1.1 Metal casting work
Casting metal is a 6,000-year-old process still used in both manufacturing and fine art. The founder
melts metal, usually aluminum, bronze and cast iron in a crucible, pours it into a mold, then removes
the mold material or the casting once the metal has cooled and solidified. The products of the metal
founding industry are manufactured in a single step from liquid metal without intermediate operations
of mechanical working such as rolling or forging. Casting is a manufacturing process by which a liquid
material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then
allowed to solidify. The solidified part is also known as a casting, which is ejected or broken out of the
mold to complete the process.
Pattern making workA poor casting may be produced from a good pattern. But a good casting will not be made from a poor
pattern. In casting, a pattern is a replica of the object to be cast, used to prepare the cavity into which
molten material will be poured during the casting process. Patterns used in sand casting may be made
of wood, metal, plastics or other materials. Patterns are made to exacting standards of construction, so
that they can last for a reasonable length of time, according to the quality grade of the pattern being
built, and so that they will reputably provide a dimensionally acceptable casting. Under certain
circumstances an original item may be adapted to be used as a pattern.
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Figure 16: Pattern of Volute casing
Pattern allowancePattern allowances in order to produce a casting of proper size and shape depend partly on product
design, mould design, shrinkage and contraction of the metal being cast. A pattern is always made
larger than the required size of the casting considering the various allowances.
These are the allowances which are usually provided in a pattern.
1. Shrinkage allowance
2. Draft allowance
3. Distortion or camber allowance
4. Rapping or Shaking allowance
5. Finishing allowance
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Core making workCores are utilized for castings with internal cavities or passages. A core is a body usually made of sand
used to produce a cavity in or on a casting cores are placed in the mould cavity before casting to from
the interior surfaces of the casting.
Figure 17: Core making
Prepare a MoldGood castings cannot be produced without good mold. Because importance of the mold. The first step
in the sand casting process is to create the mold for the casting. In an expendable mold process, this
step must be performed for each casting. A sand mold is formed by packing sand into each half of the
mold. The sand is packed around the pattern, which is a replica of the external shape of the casting.
When the pattern is the cavity that will form the casting remains. Any internal features of the casting
that cannot be formed by the pattern are formed by separate cores which are made of sand prior to the
formation of the mold. Further details on mole-making will be described in the next section. The mold-
making time includes positioning the pattern, packing the sand, and removing the pattern the mold-
making time is a affected by the size of the part, the number of cores, and the type of sand mold. If the
mold type requires heating or baking time, the mold-making time is substantially increased. The use of
lubricant also improves the flow the metal and can improve the surface finish of the casting. The
lubricant that is used is chosen based upon the sand and molten metal temperature. 42
The sand casting may be made in are:
Green sand mold
Core sand mold
Facing sand mold
Backing sand mold
Parting sand mold
Dry sand mold
Loam sand mold
Cement bonded mold
System sand mold
Prepare a mold Cavity they use some hand tools, those are:
1. Wedge
2. Gaggers
3. Blow can
4. Bellows
5. Floor rammer
6. Adjustable clamp
7. Clamp
8. Rapping iron
9. Strike
10. Rammer
11. Bench rammers
12. Molder's shovel
13. Six-foot rule
14. Cutting pliers
15. Riddle
Rising
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In addition to acting as a reservoir, a riser mitigates the hydraulic ram effect of metal entering the mold
and vents the mold. It must be the last to solidify, and to serve efficiently must conform to the
following principles. The volume of a riser must be large enough to supply all metal needed. The
gating system must be designed to establish a temperature gradient toward the riser. The area of the
connection of the riser to the casting must be large enough not to freeze too soon. On the other hand,
the connection must not be so large that the solid riser is difficult to remove from the casting.
Induction furnaceThe principle of induction melting is that a high voltage electrical source from a primary coil induces a
low voltage, high current in the metal, or secondary coil. Induction heating is simply a method of
transferring heat energy.
Induction furnaces are ideal for melting and alloying a wide variety of metals with minimum melt
losses, however, little refining of the metal is possible. There are two main types of induction furnace
coreless and channel.
Figure 18: Induction furnace
Coreless induction furnaceThe heart of the coreless induction furnace is the coil, which consists of a hollow section of heavy
duty, high conductivity copper tubing which is wound into a helical coil. Coil shape is contained
within a steel shell and magnetic shielding is used to prevent heating of the supporting shell. To protect
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it from overheating, the coil is water-cooled, the water bing reticulated and cooled in a cooling tower.
The shell is supported on trunnions on which the furnace tills to facilitate pouring.
The crucible is formed by ramming a granular refractory between the coil and a hollow internal former
which is melted away with the first heat leaving a sintered lining.
The power cubmicle converts the voltage and frequency of main supply, ot that required for electrical
melting. Frequencies used in induction melting vary from 50 cycles per second (mains frequency) to
10,000 cycles per second (high frequency). The higher the operating frequency, the greater the
maximum amount of power that can be applied to a furnace of given capacity and the lower the
amount of turbulence induced.
When the charge material is molten, the interaction of the magnetic field and the electrical currents
flowing in the induction coil produce a stirring action within the molten metal. This stirring action
forces the molten metal to rise upwards in the centre causing the characteristic meniscus on the surface
of the metal. The degree of stirring action is influenced by the power and frequency applied as well as
the size and shape of the coil and the density and viscosity of the molten metal. The stirring action
within the bath is important as it helps with mixing of alloys and melting of turnings as well as
homogenizing of temperature throughout the furnace. Excessive stirring can increase gas pick up,
lining wear and oxidation of alloys.
The coreless induction furnace has largely replaced the crucible furnace, especially for melting of high
melting point alloys. The coreless induction furnace is commonly used to melt all grades of steels and
irons as well as many non-ferrous alloys. The furnace is ideal for remolding and alloying because of
the high degree of control over temperature and chemistry while the induction current provides good
circulation of the melt.
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Figure 19: Coreless induction furnace
Channel induction furnacesThe channel induction furnace consists of a refractory lined steel shell which contains the molten
metal. Attached to the steel shell and connected by a throat is an induction unit which forms the
melting component of the furnace. The induction unit consists of an iron core in the form of a ring
around which a primary induction coil is wound. This assembly forms a simple transformer in which
the molten metal loops comprises the secondary component. The heat generated within the loop causes
the metal to circulate into the main well of the furnace. The circulation of the molten metal effects a
useful stirring action in the melt.
Channel induction furnaces are commonly used for melting low melting point alloys and or as a
holding and superheating unit for higher melting point alloys such as cast iron. Channel induction
furnaces can be used as holders for metal melted off peak in coreless induction induction units thereby
reducing total melting costs by avoiding peak demand charges.
Figure 20: Induction furnace
5.1.2 Pouring
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In a foundry, molten metal is poured into molds. Pouring can be accomplished with gravity, or it may
be assisted with a vacuum or pressurized gas. Many modern foundries use robots or automatic pouring
machines for pouring molten metal. Traditionally, molds were poured by hand using ladles.
Figure 21: Pouring molten metal
5.1.3 Degasification
In the case of aluminum alloys, a degassing step is usually necessary to reduce the amount of hydrogen
dissolved in the liquid metal. If the hydrogen concentration in the melt is too high, the resulting casting
will be porous as the hydrogen comes out of solution as the aluminum cools and solidifies. Porosity
often seriously deteriorates the mechanical properties of the metal.
An efficient way of removing hydrogen from the melt is to bubble argon or nitrogen through the melt.
To do that, several different types of equipment are used by foundries. When the bubbles go up in the
melt, they catch the dissolved hydrogen and bring it to the top surface. There are various types of
equipment which measure the amount of hydrogen present in it. Alternatively, the density of the
aluminum sample is calculated to check amount of hydrogen dissolved in it.
In cases where porosity still remains present after the degassing process, porosity sealing can be
accomplished through a process called metal.
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5.1.4 Shakeout
The solidified metal component is then removed from its mold. Where the mold is sand based, this can
be done by shaking or tumbling. This frees the casting from the sand, which is still attached to the
metal runners and gates - which are the channels through which the molten metal traveled to reach the
component itself.
5.1.5 Degating
Degating is the removal of the heads, runners, gates, and risers from the casting. Runners, gates, and
risers may be removed using cutting torches, band saws or ceramic cutoff blades. For some metal
types, and with some gating system designs, the spruce, runners and gates can be removed by breaking
them away from the casting with a sledge hammer or specially designed knockout machinery. Risers
must usually be removed using a cutting method (see above) but some newer methods of riser removal
use knockoff machinery with special designs incorporated into the riser neck geometry that allow the
riser to break off at the right place.
The gating system required to produce castings in a mold yields leftover metal, including heads, risers
and spruce, sometimes collectively called spruce, that can exceed 50% of the metal required to pour a
full mold. Since this metal must be remelted as salvage, the yield of a particular gating configuration
becomes an important economic consideration when designing various gating schemes, to minimize
the cost of excess spruce, and thus melting costs
5.1.6 Heat Treating
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.
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Figure 22: Heat treating
5.1.7 Surface cleaning
After degating and heat treating, sand or other molding media may adhere to the casting. To remove
this surface is cleaned using a blasting process. This means a granular media will be propelled against
the surface of the casting to mechanically knock away the adhering sand. The media may be blown
with compressed air, or may be hurled using a shot wheel. The media strikes the casting surface at high
velocity to dislodge the molding media (for example, sand, slag) from the casting surface. Numerous
materials may be used as media, including steel, iron, other metal alloys, aluminum oxides, glass
beads, walnut shells, baking powder among others. The blasting media is selected to develop the color
and reflectance of the cast surface. Terms used to describe this process include cleaning, bead blasting,
and sand blasting. Shot preening may be used to further work-harden and finish the surface.
5.1.8 Finishing
After completing all of casting the final step in the process usually involves grinding, sanding, or
machining the component in order to achieve the desired dimensional accuracies, physical shape and
surface finish.
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Removing the remaining gate material, called a gate stub, is usually done using a grinder or sanding.
These processes are used because their material removal rates are slow enough to control the amount
of material. These steps are done prior to any final machining.
After grinding, any surfaces that require tight dimensional control are machined. Many castings are
machined in CNC milling centers. The reason for this is that these processes have better dimensional
capability and repeatability than many casting processes. However, it is not uncommon today for many
components to be used without machining. A few foundries provide other services before shipping
components to their customers. Painting components to prevent corrosion and improve visual appeal is
common. Some foundries will assemble their castings into complete machines or sub-assemblies.
Other foundries weld multiple castings or wrought metals together to form a finished product.
More and more the process of finishing a casting is being achieved using robotic machines which
eliminate the need for a human to physically grind or break parting lines, gating material or feeders.
The introduction of these machines has reduced injury to workers, costs of consumables whilst also
reducing the time necessary to finish a casting. It also eliminates the problem of human error so as to
increase repeatability in the quality of grinding. With a change of tooling these machines can finish a
wide variety of materials including iron, bronze and aluminum.
Figure 23: After casting
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5.2 Defects of castingA casting defect is an undesired irregularity in a metal casting process. Some defects can be tolerated
while others can be repaired, otherwise they must be eliminated. They are broken down into five main
categories: gas porosity, shrinkage defects, mold material defects, pouring metal defects,
and metallurgical defects. Logical classification of casting defects presents great difficulties because of
the wide range of contributing causes, however rough classification may be made by grouping the
defects under certain broad types of origin such as.
Blowhole is a kind of cavities defect, which is also divided into pinhole and subsurface
blowhole. Pinhole is very tiny hole. Subsurface blowhole only can be seen after machining.
Burning-on defect is also called as sand burning, which includes chemical burn-on, and metal
penetration.
Sand inclusion and slag inclusion are also called as scab or blacking scab. They are inclusion
defects. Looks like there are slag inside of metal castings.
Sand hole is a kind of shrinkage cavity defect. They are empty holes after sand blasting.
Cold lap or also called as cold shut. It is a crack with round edges. Cold lap is because of low
melting temperature or poor gating system.
Joint flash is also called as casting fin, which is a thin projection out of surface of metal
castings. Joint flash should be removed during cleaning and grinding process.
Misrun defect is a kind of incomplete casting defect, which causes the casting uncompleted.
The edge of defect is round and smooth.
Shrinkage defects include dispersed shrinkage, micro-shrinkage and porosity.
Shrinkage cavities are also called as shrinkage holes, which is a type of serious shrinkage
defect.
Shrinkage depression is also a type of shrinkage defect, which looks like depressed region on
the surface of metal castings.
Elephant skin is a type of surface defect, which cause irregular or wrinkle shapes surfaces.
Veins defect is also called as rat tail, which looks like many small water flow traces on the
surface of metal castings.
5.3 Machine operation
I found several machine in MPL machine shop. Operators use these machine for different purposes.
Casting the product need machine operation to remove runner and riser, surface finishing, turning,
facing, drilling, boring, knurling, slot cutting etc. Complete those operations use some machine those
are:51
Turning: produce straight, conical, curved, or grooved work-pieces.
Facing In machining, facing is the act of cutting a face, which is a planar surface, onto the work-piece. Within
this broadest sense there are various specific types of facing, with the two most common being facing
in the course of turning and boring work (facing planes perpendicular to the rotating axis of the work-
piece) and facing in the course of milling work (for example, face milling). Other types of machining
also cut faces (for example, planning, shaping, and grinding), although the term "facing" may not
always be employed there. Unless the work is held on a mandrel, if both ends of the work are to be
faced, it must be turned end for end after the first end is completed and the facing operation repeated.
The cutting speed should be determined from the largest diameter of the surface to be faced. Facing
may be done either from the outside inward or from the center outward. In either case, the point of the
tool must be set exactly at the height of the center of rotation. Because the cutting force tends to push
the tool away from the work, it is usually desirable to clamp the carriage to the lathe bed during each
facing cut to prevent it from moving slightly and thus producing a surface that is not flat. In the facing
of casting or other materials that have a hard surface, the depth of the first cut should be sufficient to
penetrate the hard material to avoid excessive tool wear.
Figure 24: Lathe operation
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Boring Boring is the process of enlarging a hole that has already been drilled(or cast), by means of a single-
point cutting tool , for example as in boring a gun barrel or an engine cylinder. Boring is used to
achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole. Boring can be
viewed as the internal-diameter counterpart to turning, which cuts external diameters.
There are various types of boring. The boring bar may be supported on both ends (which only works if
the existing hole is a through hole), or it may be supported at one end (which works for both through
holes and blind holes). Line boring (line boring, line-boring) implies the former. Back
boring (back boring, back-boring) is the process of reaching through an existing hole and then boring
on the "back" side of the work-piece (relative to the machine headstock).
Because of the limitations on tooling design imposed by the fact that the work-piece mostly surrounds
the tool, boring is inherently somewhat more challenging than turning, in terms of decreased tool
holding rigidity, increased clearance angle requirements (limiting the amount of support that can be
given to the cutting edge), and difficulty of inspection of the resulting surface (size, form, surface
roughness). These are the reasons why boring is viewed as an area of machining practice in its own
right, separate from turning, with its own tips, tricks, challenges, and body of expertise, despite the fact
that they are in some ways identical.
PartingParting is the operation by which one section of a work-piece is severed from the remainder by means
of a cutoff tool. Because cutting tools are quite thin and must have considerable overhang, this process
is less accurate and more difficult. The tool should be set exactly at the height of the axis of rotation,
be kept sharp, have proper clearance angles, and be fed into the work-piece at a proper and uniform
feed rate.
ThreadingThreading is the process of creating a screw thread. More screw threads are produced each year than
any other machine element. There are many methods of generating threads, including subtractive
methods deformative or transformative methods additive methods (such as 3D printing); or
combinations thereof.
There are various methods for generating screw threads. The method chosen for any one application is chosen based on constraints—time, money, degree of precision needed (or not needed), what
53
equipment is already available, what equipment purchases could be justified based on resulting unit price of the threaded part (which depends on how many parts are planned), etc.
In general, certain thread-generating processes tend to fall along certain portions of the spectrum from tool room-made parts to mass-produced parts, although there can be considerable overlap. For example, thread lapping following thread grinding would fall only on the extreme tool room end of the spectrum, while thread rolling is a large and diverse area of practice that is used for everything from micro lathe lead screws (somewhat pricey and very precise) to the cheapest deck screws (very affordable and with precision to spare).
Threads of metal fasteners are usually created on a thread rolling machine. They may also be cut with a lathe, tap or die. Rolled threads are stronger than cut threads, with increases of 10% to 20% in tensile strength and possibly more in fatigue resistance and wear resistance.
KnurlingKnurling is a manufacturing process, typically conducted on a lathe, whereby a pattern of straight,
angled or crossed lines is cut or rolled into the material
Figure 25: Lathe operations
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a. Center lathe operationgeneral operations done with the lathe are grooving, turning, cutting, sanding The and etc. if
anyone wants to operate the lathe machine then he must first know about the feeds, cutting
speed, depth of the cut and usage of tool should be considered. Each lathe operation has got its
own factors that need to be considered before doing the work. The factors should be used
properly so that one can avoid from mishandling and mishaps while performing any kind of
lathe operation. With every cut desired the speed, depth and feed of the lathe machine is
changed for precision.
Figure 26: Dead Center
A lathe centerA lathe centre, often shortened to centre, is a tool that has been ground to a point to accurately position
a work-piece on an axis. They usually have an included angle of 60°, but in heavy machining
situations an angle of 75° is used.
The primary use of a centre is to ensure concentric work is produced; this allows the work-piece to be
transferred between machining (or inspection) operations without any loss of accuracy. A part may
be turned in a lathe, sent off for hardening and tempering and then ground between centers in
a cylindrical grinder. The preservation of concentricity between the turning and grinding operations is
crucial for quality work.
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A center is also used to support longer work-pieces where the cutting forces would deflect the work
excessively, reducing the finish and accuracy of the work-piece, or creating a hazardous situation.
A centre lathe has applications anywhere that a centered work-piece may be used; this is not limited to
lathe usage but may include setups in dividing heads, cylindrical grinders, tool and cutter grinders or
other related equipment. The term between centres refers to any machining operation where the job
needs to be performed using centers
Figure 27: Lathe
A live center
Live center is constructed so that the 60° center runs in its own bearings and is used at the non-driven
or tailstock end of a machine. It allows higher turning speeds without the need for separate lubrication,
and also greater clamping pressures. CNC lathes use this type of center almost exclusively and they
may be used for general machining operations as well. Spring loaded live centers are designed to
compensate for center variations, without damage to the work-piece or center tip. This assures the
operator of uniform constant tension while machining. Some live centers also have interchangeable
shafts. This is valuable when situations require a design other than a 60° male tip.
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A drive
Center is used in the driving end of the machine (headstock). It consists of a dead center surrounded by
hardened teeth. These teeth bite into the softer work-piece allowing the work-piece to be driven
directly by the center. This allows the full diameter of the work-piece to be machined in a single
operation, these contrasts with the usual requirement where a carrier is attached to the work-piece at
the driven end. They are often used in woodworking or where softer materials are machined. Drive
Centre is also known as Grip center in some industrial circles. Another modification made to the Drive
center is that Shell End Mills are modified and used instead of hardened pins that enable better
gripping and also that used of used Shell end mills after grinding the edges. This prevents breakdown
time due to pin breakage.
b. Turret lathe
The particular sphere of the turret, and the use of the various tools and tool-holding devices, can be best explained by illustrating and describing some of the more important operations in the machining of castings of the usual forms.Some of the practical observations applicable to the handling of the work and the tools are given, and their importance should be fully realized by the novice in attempting turret-lathe work.Great care should be used to have all tools, tool-holders, attachments, fixtures, etc., securely clamped in place, so that there will be no danger of their working loose, and vibration will be eliminated as far as possible.
The tools should be ground to the correct shape, and the finishing tools should be carefully stoned with a fine-grained oil-stone so that their cutting edges will be smooth and keen. They will then do much smoother work, and the cutting edges will last much longer.
Generally there must be a roughing and a finishingcut, the same as in an ordinary lathe. In the turret lathe the two cuts are made by different tools, so as to avoid constant changes of adjustment.
Stop-gages should be carefully set so that correct dimensions may be produced when the turret slide or cross-slide, as the case may be, is run firmly against the stop, but so that there is no straining or forcing of it. Unless care is used in this respect, correct dimensions cannot be maintained.
57
Proper speeds must be used, according to the rialto be machined and the diameter of the work. The same speeds will be used as for engine lathes. When tapping or desire used, the speed, on the cut, must be very materially reduced.
In chucking comparatively thin cylindrical work, it should be held by the outside, as there is much less danger of breaking it than if it is held by the inside.
In machining heavy-rimmed balance wheels, they are frequently held by the inside of the rim so as to leave the outside and face clear for the tools.
Pulleys and similar light wheels are frequently held by the arms, which rest against suitable supports so as to avoid distortion and to leave the rims and hub free for machining operations.
In boring operations, particularly deep holes, the tool should be made with a long guiding end or pilot, which may enter a bushing in the main spindle of the machine before the tool commences to cut. This will reduce vibration and chatter, insure a true hole, and prolong the life of the tool.
When the piece of work is comparatively long-that is, projects to a considerable distance from the chuck-the outer end should be run in a center rest similar to that on an engine lathe, to hold it true and rigid, and to insure true and accurate work.
Figure 28: A Turret lathe
The turret lathe has been in use since the mid-19th century. Its development was an important one for
manufacturers. Before the turret lathe came into existence, making quality metal tools or components
was dependent on the skill of the operator. Once it started being used in manufacturing plants, it meant
that tools and other parts could be made quicker and at a lower cost
d. Milling machine operation
Milling is the machining process of using rotary cutters to remove material from a work-piece
advancing (or feeding) in a direction at an angle with the axis of the tool. It covers a wide variety of
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different operations and machines, on scales from small individual parts to large, heavy-duty gang
milling operations. It is one of the most commonly used processes in industry and machine shops
today for machining parts to precise sizes and shapes.
Milling can be done with a wide range of machine tools. The original class of machine tools for
milling was the milling machine (often called a mill). After the advent of computer numerical control
(CNC), milling machines evolved into machining centers (milling machines with automatic tool
changers, tool magazines or carousels, CNC control, coolant systems, and enclosures), generally
classified as vertical machining centers (VMCs) and horizontal machining centers (HMCs). The
integration of milling into turning environments and of turning into milling environments, begun with
live tooling for lathes and the occasional use of mills for turning operations, led to a new class of
machine tools, multitasking machines (MTMs), which are purpose-built to provide for a default
machining strategy of using any combination of milling and turning within the same work envelope.
Figure 29: Milling machine
Process
Milling is a cutting process that uses a milling cutter to remove material from the surface of a work-
piece. The milling cutter is a rotary cutting tool, often with multiple cutting points. As opposed
to drilling, where the tool is advanced along its rotation axis, the cutter in milling is usually moved
perpendicular to its axis so that cutting occurs on the circumference of the cutter. As the milling cutter
enters the work-piece, the cutting edges (flutes or teeth) of the tool repeatedly cut into and exit from
59
the material, shaving off chips (swarf) from the work-piece with each pass. The cutting action is shear
deformation; material is pushed off the work-piece in tiny clumps that hang together to a greater or
lesser extent (depending on the material) to form chips. This makes metal cutting somewhat different
(in its mechanics) from slicing softer materials with a blade.
The milling process removes material by performing many separate, small cuts. This is accomplished
by using a cutter with many teeth, spinning the cutter at high speed, or advancing the material through
the cutter slowly; most often it is some combination of these three approaches. [2] The speeds and
feeds used are varied to suit a combination of variables. The speed at which the piece advances
through the cutter is called feed rate, or just feed; it is most often measured in length of material per
full revolution of the cutter.
There are two major classes of milling process:
In face milling, the cutting action occurs primarily at the end corners of the milling cutter. Face
milling is used to cut flat surfaces (faces) into the work-piece, or to cut flat-bottomed cavities.
In peripheral milling, the cutting action occurs primarily along the circumference of the cutter,
so that the cross section of the milled surface ends up receiving the shape of the cutter. In this
case the blades of the cutter can be seen as scooping out material from the work-piece.
Peripheral milling is well suited to the cutting of deep slots, threads, and gear teeth.
Types of teeth
The teeth of milling cutters may be made for right-hand or left-hand rotation, and with either right-
hand or left-hand helix. Determine the hand of the cutter by looking at the face of the cutter when
mounted on the spindle. A right-hand cutter must rotate counterclockwise; a left-hand cutter must
rotate clockwise. The right-hand helix is shown by the flutes leading to the right; a left-hand helix is
shown by the flutes leading to the left. The direction of the helix does not affect the cutting ability of
the cutter, but take care to see that the direction of rotation is correct for the hand of the cutter.
Saw Teeth
Saw teeth similar to those shown in Figure 8-3 are either straight or helical in the smaller sizes of plain
milling cutters, metal slitting saw milling cutters, and end milling cutters. The cutting edge is usually
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given about 5 degrees primary clearance. Sometimes the teeth are provided with off-set nicks which
break up chips and make coarser feeds possible.
Helical Milling Cutters
Milling cutters are cutting tools typically used in milling machines or machining centres to
perform milling operations (and occasionally in other machine tools). They remove material by their
movement within the machine (e.g. a ball nose mill) or directly from the cutter's shape.
Metal Slitting Saw Milling Cutter
The metal slitting saw milling cutter is essentially a very thin plain milling cutter. It is ground slightly
thinner toward the center to provide side clearance. These cutters are used for cutoff operations and for
milling deep, narrow slots, and are made in widths from 1/32 to 3/16 inch.
Side Milling Cutters
Side milling cutters are essentially plain milling cutters with the addition of teeth on one or both sides.
A plain side milling cutter has teeth on both sides and on the periphery. When teeth are added to one
side only, the cutter is called a half-side milling cutter and is identified as being either a right-hand or
left-hand cutter. Side milling cutters are generally used for slotting and straddle milling.
Interlocking tooth side milling cutters and staggered tooth side milling cutters are used for cutting
relatively wide slots with accuracy. Interlocking tooth side milling cutters can be repeatedly sharpened
without changing the width of the slot they will machine.
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Figure 30: Various Types of Milling cutter
After sharpening, a washer is placed between the two cutters to compensate for the ground off metal.
The staggered tooth cutter is the most washers are placed between the two cutters to compensate for
efficient type for milling slots where the depth exceeds the width.
End Milling Cutters
An end mill is a type of milling cutter, a cutting tool used in industrial milling applications. It is
distinguished from the drill bit in its application, geometry, and manufacture. While a drill bit can only
cut in the axial direction, a milling bit can generally cut in all directions, though some cannot cut
axially.
End mills are used in milling applications such as profile milling, tracer milling, face milling, and plunging.
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Figure 31: Taper used in milling machine
T-Slot Milling Cutter
The T-slot milling cutter is used to machine T-slot grooves in worktables, fixtures, and other holding
devices. The cutter has a plain or side milling cutter mounted to the end of a narrow shank. The throat
of the T-slot is first milled with a side or end milling cutter and the headspace is then milled with the
T-slot milling cutter.
Woodruff Key slot Milling Cutters
The Woodruff key slot milling cutter is made in straight, tapered-shank, and arbor-mounted types. The
most common cutters of this type, under 1 1/2 inches in diameter, are provided with a shank. They
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have teeth on the periphery and slightly concave sides to provide clearance. These cutters are used for
milling semi cylindrical keyways in shafts.
Figure 32: Woodruff Key slot cutter
e) Shaper machine operation
ShaperA shaping machine is used to machine surfaces. It can cut curves, angles and many other shapes. It is a
popular machine in a workshop because its movement is very simple although it can produce a variety
of work.
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Figure 33: Shaper Machine
Lubricating the shaper Oil reservoir Motor Sliding surface of the tool head.
Oil pressure gauge
Table support surface Clapper pin.
Feed screw.
Oil feed box
Oil hole of ram.
.
OperationThe work-piece mounts on a rigid, box-shaped table in front of the machine. The height of the table
can be adjusted to suit this work-piece, and the table can traverse sideways underneath the
reciprocating tool, which is mounted on the ram. Table motion may be controlled manually, but is
usually advanced by an automatic feed mechanism acting on the feed screw. The ram slides back and
forth above the work. At the front end of the ram is a vertical tool slide that may be adjusted to either
side of the vertical plane along the stroke axis. This tool-slide holds the clapper box and tool post, from
which the tool can be positioned to cut a straight, flat surface on the top of the work-piece. The tool-
slide permits feeding the tool downwards to deepen a cut. This adjustability, coupled with the use of
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specialized cutters and tool holders, enable the operator to cut internal and external gear tooth profiles,
splines, dovetails, and keyways.
The ram is adjustable for stroke and, due to the geometry of the linkage, it moves faster on the return
(non-cutting) stroke than on the forward, cutting stroke
f. Grinding operation
GrindingGrinding is an abrasive machining process that uses a grinding wheel as the cutting tool.
A wide variety of machines are used for grinding:
Hand-cranked knife-sharpening stones (grindstones)
Handheld power tools such as angle grinders and die grinders
Various kinds of expensive industrial machine tools called grinding machines
Bench grinders often found in residential garages and basements
Parts of grinding Machine Base.
Work table.
Wheel head and slide.
Head stock and tail stock.
Spindle.
Application
To remove a very small amount of metal from that work-piece to bring its dimension with in very
close tolerance after all the rough finishing. To obtained batter surface finish on the surface.
Abrasive An abrasive is a hard material which can be used to cut or wear away other material. It is externally
hard and tough and when fractured, it forms sharp cutting edge and corner. Abrasive materials are sand
stone or solid quartz, emery (50-60%) crystalline Al2O3+ Iron oxide, corundum (75-95%) crystalline
Al2O3+ Iron oxide, diamonds and garnet.
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Drilling Operation
Drill MachineDrill machine is one of the simplest and accretes machine tool used in production shop and tool room.
Drilling is a process of making hole.
Drilling.
Boring.
Countersinking.
Trepanning
Rivet spanning.
Reaming.
Polishing.
Counter boring.
Spot facing.
Toping
Parts of drilling machine Base.
Column.67
Table.
Drill Head.
Electric motor.
Gear box.
Illustrate work holding methods Machine vise.
Clamping block.
Angle plate.
Parallel strips.
Tool makers clamps.
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Chapter Six
Pump Assembly Section
Pump Assembly Section
When the machining is done and all the parts are completed as fit to assemble, the following works is
done in the assembly shop:69
The assembly of the pump is carried in the vertical position. This prevents the risk of shaft or
bowl assembly to develop sag. The bowl bushing clearance is typically 9 mils and in a
horizontal position it is bound to touch after 3–4 bowl assemblies as the bowl have a spigot fits
of 2–3 mils. In a vertical position, these get distributed.
The jack-bolt in the suction piece must be used to position the end of the shaft to allow for
accurate spacing of the impellers.
Impellers fitted with collets in comparison to those held by splitting; keys, snap rings, and
others need a lot more attention. Excessive tightening of the cullet can lead to cracking of the
impeller in the hub area.
After the pump bowls have been assembled, the lift should be checked and the rotor should to
rotated by hand to check for any rubbing of internals.
If the length of the pump is large, column sections have to be assembled in a horizontal
position.
The assembled positions should be rotated 180° with installation of every additional
component. This aids in staggering the alignment clearances, fits through the length of the
columns, and helps to keep the assembly along the shaft centerline.
After the columns have been fitted, the discharge head is installed. At this stage, the shaft
extension length can be compared with the ones taken before dismantling of the pump.
Deviations of 1/16th to 1/8th are considered as normal and can be compensated with the use of
gaskets.
The shaft extension maybe supported and the shaft can be locked before dispatching it to the site. If the
jack bolt at the suction bell is left in place, it should accompany a warning tag to remove it before
installation.
Every part of a pump those are individually produce in side this factory those parts are assembled
together in this section. Centrifugal pumps are rot dynamic pumps and operate normally primed. They
are in widespread use, and are deployed primarily in the pumping of water. Their applications include
use in shipbuilding, the process industries and in water supply systems. They are compact and
relatively simple in design. The parts are shown here symmetrically.
The assembly process begins at the pump shaft, which has undergone checks for runouts, condition of
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steps/shoulders, keyways, and fits.
6.1 Bearing assembly
Always keep the cover on grease can so that no dirt can enter.
Be sure the instrument with which you take the grease from the can is clean. Avoid using a
wooden paddle, but rather use a steel blade or putty knife that can be wiped off smooth and
clean
In cases where a grease gun is used to introduce grease into bearing chamber, observe the same
caution regarding the cleanliness of the gun, especially the nozzle and the grease fittings.
The bearing should be pressed on squarely. Do not cock it on to the shaft. Be sure that the
sleeve used to press the bearing on is clean, cut square, and contacts the inner race only.
The bearing should be pressed firmly against shaft shoulder. The shoulder helps to support and
square the bearing.
In case the fits are tight, the bearings maybe heated using an induction heater with a de-
magnetizing cycle. The temperature should not increase beyond 110 ºC.
The bearings should be lubricated.
Fit the cone of bearing to shaft with large diameter against retainer. It is advisable to preheat
bearing cone. (Preheat should not exceed 210°F.) Warm an suggests using an induction heater
or oven to heat the bearings.
This assembly should then be wrapped in a plastic cover while the bearing housing is made
ready.
Prior to placing the rotor in the bearing housing, it is insured that it is spotlessly clean.
Oil is smeared on the bearing housing bores.
Shaft with the mounted bearings is tapped in the bearing housing till the outer race of the
inboard bearing rests against the step.
6.2 Seal assembly
The stationary seat is firmly clamped with the seals in the seal end plate.
Place expeller ring (flat on bench (gland seal up).
Drop neck ring into gland recess so it rests on the retaining lip.
Stand shaft sleeve on end and place through neck ring.
Assemble gland halves, insert gland clamp bolts, and fully tighten. Place gland into expeller
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ring, pushing it down to compress the packing rings. Insert gland bolts and snug nuts
sufficiently to hold shaft sleeve.
Fit shaft sleeve o-ring on shaft and slide up to labyrinth. apply anti-seize lubricant to exposed
shaft, including threads.
Insert assembled expeller ring into frame plate, tapping into position with a mallet. Locate
expeller ring with the grease inlet at top.
Fit second shaft sleeve o-ring and push into recess in the end face of the shaft sleeve.
Place expeller onto the shaft and press up to the shaft sleeve.
Assembly of gland lubricating parts is done after all other parts of pump have been assembled.
6.3 Impeller and casing assembly
Once the sleeve with rotary head is placed, the compression is achieved after installing the
impeller and locking it to the shaft with the help of the nut.
After the impeller is fixed, it is a good idea to measure the run out of the impeller wearing ring
in this installed condition. This should be within 0.05 mm.
The casing gasket is placed in the pump casing.
The casing is then bolted to the seal-housing flange, once again taking care of the match marks.
The bolts are tightened to the specified torque value.
Installation of coupling, lines, and fittings
The pump coupling half can now be mounted onto the shaft.
Shaft end should preferably be flush with the coupling half. However, if it was not so
originally, this should have been recorded and kept along similar lines.
The sealant lines, oil level gages, cooling water lines, or any other should be fitted.
After the blind flanges are removed, the pump nozzles should be completely covered by a tape.
The pump is ready for installation at site.
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73
Chapter: Seven
Pump Testing Section
Pump Testing Section
The basis of centrifugal pump testing is a direct function of its criticality to its application. For
example, an ordinary garden water pump would not require the same kind of attention as a boiler feed
water pump in a major power plant or a firewater pump in a refinery.
The criticality of any pump equipment is based on the following criteria:
Failure can affect plant safety
Essential for plant operation and where a shutdown will curtail the process
throughput
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No standby or installed spares.
Large horsepower pumps
High capital cost and expensive to repair or longer repair lead time
Perennial pumps that wreck on the slightest provocation of an off-duty operation
Finally, pump trains, where better operation could save energy or improve yields
are also likely candidates.
Once the criticality of a pump can be ascertained based on the factors mentioned, the pumps can be
classified as:
• Critical
• Essential
• General purpose.
After this categorization, the type of maintenance philosophy can be assigned. The pumps, which fall
in the category of critical machines, are usually maintained with the predictive and proactive
techniques.
The essential category pumps are assigned with preventive maintenance whereas maintenance
for the general-purpose pumps maybe less stringent.
In actual operations, a mix and match of techniques is applied with a prime intention of
maximizing runtime lengths and reducing downtime and costs.
The present day focus on continuous process plant pumps is to adopt a mix of Predictive and
Preventative Maintenance (PPM)
There are four areas that should be incorporated in a PPM program. Individually, each one will provide
information that gives an indication of the condition of the pump; collectively, they will provide a
complete picture as to the actual condition of the pump.
These include:
• Performance monitoring
• Vibration monitoring
• Oil and particle analysis
• System analysis.
7.1 Performance monitoringThe following six parameters should be monitored to understand how a pump is performing:
1. Suction pressure (Ps)
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2. Discharge pressure (Pd)
3. Flow (Q)
4. Pump speed (N)
5. Pump efficiency (η)
6. Power.
Analysis of efficiency or inefficiency can help one to determine whether the losses are
on account of:
• Hydraulic losses
• Internal recirculation
• Mechanical losses.
Direct reading thermodynamic pump efficiency monitors (such as the Yates meter) are now available
and capable of interpreting the pump’s operating efficiency in a dynamic manner by measuring and
computing the rise in temperature (albeit in mk) of the fluid as it moves from the suction to the
discharge side of the pump.
Motor efficiency obtained from the manufacturer of the electric motor and drive losses are factored in
to the software program, to then calculate the operating efficiency of the pump.
This reading could be compared with the pump’s commissioning data and drop in performance or
efficiency could be determined.
7.2 Required EquationsHead H=Suction gauge reading×0.346+Delivery gauge reading ×10.21+0.34 (m)
Discharge Q={372-V notch high/304.8}2.47×2.52 (m3/hr)
W.H.P= (Head ×Discharge×2.727/746) (kw)
I.H.P= (Watt meter reading/.746) (kg)
Efficiency ηc=W.H.P/I.H.P
7.4 Requirements
There is some terms those are very important to test properly those are:
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a. Check Valve Most centrifugal pumps cannot run dry; ensure that the pump is always full of liquid. In residential
systems, to ensure that the pump stays full of the liquid use a check valve (also called a foot valve)
at the water source end of the suction line. Certain types of centrifugal pumps do not require a check
valve as they can generate suction at the pump inlet to lift the fluid into the pump. These pumps are
called jet pumps and are fabricated by many manufacturers Gould’s being one of them.
b. Do not let a pump run at zero flow
Do not let a centrifugal pump operate for long periods of time at zero flow. In residential systems, the
pressure switch shuts the pump down when the pressure is high which means there is low or no flow.
c. Pressure Gauges
Make sure your pump has a pressure gauge on the discharge side close to the outlet of the pump this
will help you diagnose pump system problems. It is also useful to have a pressure gauge on the suction
side; the difference in pressure is proportional to the total head. The pressure gauge reading will have
to be corrected for elevation since the reference plane for total head calculation is the suction flange of
the pump.
Figure 34: A pressure Gauge
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a. Flow and pressure relationship of a pump
When the flow increases, the discharge pressure of the pump decreases, and when the flow decreases
the discharge pressure increases.
b. Suction Valves
Gate valves at the pump suction and discharge should be used as these offer no resistance to flow and
can provide a tight shut-off. Butterfly valves are often used but they do provide some resistance and
their presence in the flow stream can potentially be a source of hang-ups which would be critical at the
suction. They do close faster than gate valves but are not as leak proof.
c. Eccentric Reducer
Always use an eccentric reducer at the pump suction when a pipe size transition is required. Put the
flat on top when the fluid is coming from below or straight (see next Figure) and the flat on the bottom
when the fluid is coming from the top. This will avoid an air pocket at the pump suction and allow air
to be evacuated.
d. Use a multi-stage turbine pump for deep well
For deep wells (200-300 feet) a submersible multi-stage pump is required. They come in different sizes
(4" and 6") and fit inside your bore whole pipe.
e. Flow control
If you need to control the flow, use a valve on the discharge side of the pump; never use a valve on the
suction side for this purpose.
f. Plan ahead for flow meters
For new systems that do not have a flow meter, install flanges that are designed for an orifice plate in a
straight part of the pipe and do not install the orifice plate. In the future, whoever trouble-shoots the
78
pump will have a way to measure flow without the owner having to incur major downtime or expense.
Note: orifice plates are not suitable for slurries.
g. Avoid pockets and high points
Avoid pockets or high point where air can accumulate in the discharge piping. An ideal pipe run is one
where the piping gradually slopes up from the pump to the outlet. This will ensure that any air in the
discharge side of the pump can be evacuated to the outlet.
h. Location of control valves
Position control valves closer to the pump discharge outlet than the system outlet. This will ensure
positive pressure at the valve inlet and therefore reduce the risk of Cavitation’s. When the valve must
be located at the outlet such as the feed to a tank, bring the end of the pipe to the bottom of the tank
and put the valve close to that point to provide some pressure on the discharge side of the valve
making it easier to size the valve, extending its life and reducing the possibility of Cavitation’s.
Figure 35: Pump test branch
i. Water hammer79
Be aware of potential water hammer problems. This is particularly serious for large piping systems
such as are installed in municipal water supply distribution systems. These systems are characterized
by long gradually upward sloping and then downward sloping pipes. Solutions to this can involve
special pressure/vacuum reducing valves at the high and low points or additional tanks which provide
a buffer for pressure surges.
j. The right pipe size
The right pipe size is a compromise between cost (bigger pipes are more expensive) and excessive
friction loss (small pipes cause high friction loss and will affect the pump performance). Generally
speaking, the discharge pipe size can be the same size as the pump discharge connection, you can see
if this is reasonable by calculating the friction loss of the whole system. For the suction side, you can
also use the same size pipe as the pump suction connection, often one size bigger is used .A typical
velocity range used for sizing pipes on the discharge side of the pump is 9-12 ft/s and for the suction
side 3-6 ft/s.
A small pipe will initially cost less but the friction loss will be higher and the pump energy cost will be
greater. If you know the cost of energy and the purchase and installation cost of the pipe you can select
the pipe diameter based on a comparison of the pipe cost vs power consumption.
k. Pressure at high point of system
Calculate the level of pressure of the high point in your system. The pressure may be low enough for
the fluid to vaporize and create a vapor pocket which will be detrimental to the performance of the
system. The pressure at this point can be increased by installing a valve at some point past the high
point and by closing this valve you can adjust the pressure at the high point. Of course, you will need
to take that into account in the total head calculations of the pump.
7.5 Quality Assurance
Quality Assurance refers to administrative and procedural activities implemented in a quality system
so that requirements and goals for a product, service or activity will be fulfilled. It is the systematic
measurement, comparison with a standard, monitoring of processes and an associated feedback loop
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that confers error prevention. This can be contrasted with quality control which is focused on process
output.
Two principles included in Quality Assurance are: "Fit for purpose", the product should be suitable for
the intended purpose; and "Right first time", mistakes should be eliminated. QA includes management
of the quality of raw materials, assemblies, products and components, services related to production,
and management, production and inspection processes.
7.5.1 Statistical control
Statistical control is based on analyses of objective and subjective data. Many organizations use
statistical process control as a tool in any quality improvement effort to track quality data. Any product
can be statistically charted as long as they have a common cause variance or special cause variance to
track.
7.5.2 Total quality management
The quality of products is dependent upon that of the participating constituents some of which are
sustainable and effectively controlled while others are not. The process(es) which are managed with
QA pertain to Total Quality Management.
If the specification does not reflect the true quality requirements, the product's quality cannot be
guaranteed. For instance, the parameters for a pressure vessel should cover not only the material and
dimensions but operating, environmental, safety, reliability and maintainability requirements.
7.5.3 MPL Assured Quality
MPL is ISO 9001:2000 Quality Certified. It is confidential that the replacement parts will be
dimensionally correct and the material specified will be the material received. Over the last 40
years MPL has established a reputation in the industrial market place for providing only the
highest quality pump and rotating equipment replacement parts.
100% dimensional inspection of all parts. Documentation is recorded and filed.
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All pressure containing components are hydro tested.
All impellers and rotating elements are balanced to ISO as standard. Special balance
specifications can be achieved.
To ensure castings meet customer expectations and requirements for quality, delivery and
price, Flowserve employs a quality assurance program that involves several processes.
While many foundries purchase “master melt,” Flowserve possesses in-house capability to
blend and analyze metals. This assures consistent and optimal chemistry, corrosion resistance
and mechanical properties.
All operations are carefully controlled and documented through a series of technical
specifications to assure consistency.
Every heat is analyzed at least twice to guarantee compositional integrity.
Chapter: Eight
Problems and Solution
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8.1 LOCATION LOGIC
One of the first decisions faced by pump users is where to locate the pump. This may seem like a very simple matter, but all too often it’s where many pump problems begin. An ill-considered placement, where the pump is exposed to extreme temperature conditions, or too far from the supply vessel, can be the source of considerable trouble down the road.
Clogged or blocked suction strainer
System discharge pressure greater than pump internal relief valve setting
Starved suction
Pumps properly installed with piping fully supported prevents stress on component connections. The installation of unions will help simplify pump servicing to the supply vessel as practical, to help minimize friction loss in the suction piping.
Always take into account the environment in which your pump will be located, since extreme temperature fluctuations, particularly on pumps installed outdoors, can have a pronounced effect on metering pump performance. For example, pumps installed where temperatures fall below freezing should be equipped with a heat source to prevent chemical freezing.
It’s also important to change hydraulic oil in pump to reflect changing temperature conditions. In addition, you’ll want to sufficiently protect all components from rain, snow and ice. Failure to do so could result in a situation similar to the following:
Clean or replace (suction line was not flushed prior to making connection to pump, permitting solids or debris such as pipe sealant, tape, etc. to enter and block check valves)
Check and reset relief valve (within pump rating)
Insufficient NPSH. Shorten suction piping, increase suction piping size or suction head.
Probable Cause
Insufficient hydraulic oil
Clogged or blocked check valves, or check valves held open by solids
Remedies
Fill the pump to proper level.
Problem: A leading Gulf Coast chemical manufacturer experienced total operating failure shortly after start-up of several new metering pumps equipped with electronic capacity control actuators.
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Solution: The service technician discovered that the installation contractor had removed the pumps! actuators from factory-supplied baseplates, resulting in serious misalignment problems.
Although installed outdoors, the contractor had wired the pumps and actuators using indoor-type non- watertight electrical connectors. This allowed rain to thoroughly penetrate wiring and enter the pumps and actuators, shorting-out critical electronic components.
Alter realigning pumps and actuators, rewiring them with watertight electrical connectors, and replacing the damaged electronic parts, the pumps operated properly.
8.2 SUCTION PIPING
Nearly 85% of all metering pump operating problems can be directly attributed to suction difficulties, either because of undersized suction piping or due to blockage and/or restrictions in the suction line.
Unlike the steady flow characteristics of a centrifugal pump, a reciprocating metering pump with its pulsating flow requires piping large enough to handle the peak instantaneous flow, which is three times greater than the rated pump capacity. Thus, a metering pump rated at 60 gph produces a 188 gph peak instantaneous flow rate. (60 gph x 3.14 = 188 gph)
Problems can be avoided by keeping suction lines as short and as straight as possible. Piping should be sloped, if necessary, to eliminate vapor pockets. Although suction pipe size requirements vary greatly with each application, a good ‘rule of thumb” is
Probable Cause
Partially clogged/dirty suction strainer
Insufficient hydraulic oil
Leak in suction piping
Internal or external relief valve is relieving
Insufficient suction pressure
Worn or dirty check valves.
Liquid close to boiling point
Liquid viscosity too high
Remedies
Clean strainer
Fill to proper level
84
Repair piping
Reset valve
Raise liquid tank level
8.3 PUMP MOTOR FAILS TO START
Probable Cause
Blown fuse or tripped breaker
Open thermal overload in motor starter
Low line current
Open circuit in limit switches, timers or other control devices in pump motor starter circuit
Motor damage
Remedies
Replace fuse after correcting cause of overload
Reset after correcting cause of overload. If malfunction recurs, check heater size
Determine cause and correct
Reset
Check motor for physical damage that may hinder operation
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Recommendations &
Conclusion
86
Recommendations & Conclusion
The company is professionally managed by a team of experienced professionals who are highly
qualified. As its Quality Policy states that it is eager to adopt new and advanced technologies to
provide service to the customers with satisfaction.
With these view the following recommendations are made for Milnars Pumps Limited.
Metal waste should be reduced by operation and maintenance to get more benefit.
All the equipment should be kept orderly.
Skilled and dedicated team need to monitor all the activities.
All should aware of workers about SOP.
Proper instructions should be followed for any kind of problem.
Cost for operation and maintenance need to be reduced.
Skilled and dedicated engineers need to monitor all the activities.
Customer requirements should be ensured.
Workers satisfy should be ensured and they need to work with joy.
Maintenance schedule should be followed properly.
The practicum has been completed successfully by the grace of Allah. Practicum sends to the expected
destiny of practical life. The completion of the practicum at “Milnars Pumps Ltd” The impression that
factory is of the most modern input oriented machinery composite company in Bangladesh. Though it
was established by a many years ago.
now i can say that i have a clear concept on working principle, manufacturing as well as testing of
pumps. We should make our own sketch of the system that includes all the information on the MPL
plus elevations (max., min., in, out, equipment), path of highest total head, fluid properties, max. And
min. flow rates and anything pertinent to total head calculations. Depending on the industry that i work
in. I hope it will help me in my service life immensely. During the training period all the association
from the authority has been help and fulfill all activities for our appreciable working condition. All
staffs and officers were very sincere and devoted their duties to achieve their goal. The practicum is an
important and essential part of education as through this training i learn all the implementations of the
process which i have studied theoretically. It gives us an opportunity to compare the theoretical
knowledge with practical facts and thus develop my knowledge and skills. This training also gives me
an opportunity to enlarge my knowledge about my operation of machineries teaches us to adjust with 87
the practical life. At the end of the day I realized that training make our knowledge’s
application practically and make us confident to face any problem of our job sector.
Milnars Pumps Ltd. is a leading metal casting in our country. The company is professionally managed
by a team of experienced professionals and promoted by highly qualified and experienced personnel’s.
To support our country economy and requirement fulfill of countrymen. I observed that MPL will be
in the leading of supplying pumps in the field of agricultural undertakings, irrigation & drainage,
general water supply duties for municipal, community, industrial and pressure boosting, textile
industries, organic and inorganic corrosive liquids in chemical handling, pharmaceutical industries and
petrochemical plants. Pumping of sea water, hot water condensate, cooling water, oil circulation, oil
inshore shipping etc. at the end I was past a quality time with the stuff of MPL when i were there.
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88
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Laws and Pump Applications – By, M. R. Branda – Cutler-Hammer
http://www.drivesmag.com
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Hydrocarbon Processing – April 1982.
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International Pump Users Symposium; 1995.
11. RA Mueller Inc – Pump Handbook http://www.ramueller.com/handbook.htm
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