Chapter: One

Introduction

1

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

2

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.

3

Chapter: Two

Company Overview

4

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

5

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 :sales@milnarspumps.com, milnars@bdmail.com

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

8

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

14

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

15

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.

17

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.

18

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

22

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

23

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.

29

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.

31

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.

32

.

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

33

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

37

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.

40

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

44

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.

45

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

46

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.

47

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.

49

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

52

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

54

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.

55

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.

56

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

58

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

63

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

65

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.

66

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

70

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

71

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

74

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)

75

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:

76

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

80

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

82

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.

83

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

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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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Annual Meeting of ASME, Washington D.C- Nov 15-20, 1981.

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2. Learning about NPSH Margin –

http://www.pumps.org/public/pump_resources/discussion/NPSH_Standard/

pump_NPSH_margin.htm

3. Pump shaft radial thrust alternative calculations (in Imperial dimensions) 13-2.

http://www.mcnallyinstitute.com

4. Bearings in Centrifugal Pumps – SKF Application Handbook.

5. Pump Controls – A dollars and sense approach by Kevin Tory, Manager, applications

and training, Cutler-Hammer, Eaton Corporation, Milwaukee, Wisconsin- FHS (Fluid

Handling Systems) – March 1999.

6. Adjustable Frequency Drives and Saving Energy – Part One – The Basics, The Affinity

Laws and Pump Applications – By, M. R. Branda – Cutler-Hammer

http://www.drivesmag.com

7. Centrifugal Pumps: Trouble shooting minimum flow and temperature rise

http://www.iglou.com/pitt/minimum.htm

8. Centrifugal Pump Specification and Selection – A System’s Approach, StanT.

Shiels 5th International Pump Users Symposium Pump; –1988.

9. Centrifugal Pumps – Which Suction Specific Speeds are acceptable? J.L. Hallam-

Hydrocarbon Processing – April 1982.

10. Centrifugal Pumps Inspection and Testing – Vinod P. Patel, James R. Bro 12th

International Pump Users Symposium; 1995.

11. RA Mueller Inc – Pump Handbook http://www.ramueller.com/handbook.htm

12. R.S Khurmi, A Text Book Of Hydraulics, Fluid Mechanics And Hydraulic Machines-

Nineteenth Edition,2014- S. Chand & Company Ltd. Ramnagar, New Delhi-110055.

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