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An internship report on

SNGPL Faisalabad.

Submitted to

Sir Zahid Rasheed

Adimin Officer Gr-III (D)

Submitted by

Noor Ul Ain Sabir 2008-Chem-09

Umar Abbas 2009-Chem-27

Department of Chemical Engineering University of Engineering and Technology, Lahore.

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In The Name Of ALLAH

The Most Beneficent, The Most Merciful

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Table of contents

ACKNOWLEDGEMENT ……………………………………………………………………….. 5

PREFACE ................................................................................................. 6

Internship Objectives.............................................................................. 7

1. An Introduction to (SNGPL)………….….……………………………………….…….. 8

1.1 Vision Statement ………………………………………………………….……………… 9

1.2 Mission Statement…………………………………………………………………….….. 9

1.3 Services………………………………………………………………………….……………… 9

1.4 Natural Gas……………………………………………………………………….………….. 9

Gas Sources………………………………………………….…………………………..…………. 10

2. SNGPL’s Distribution Department …….……..……………………………….…….. 11

2.1 Operations of Distribution ……………………………………………………………….. 11

2.2 Departments of SNGPL [D]……..........………………………………………………. 11

3. GENERAL…………………………………………………………………………………………... 12

3.1Gas Network…………………………………………………………………………………….. 12

3.2 Important Terms……………………………………………………………………….…….. 12

4. Working of Distribution’s Departments……………………………………………….. 14

4.1 Development…………………………………………………………………………………….. 14

4.1.1 Sizing…………………………………………………………………………………………..….. 15

4.1.2 Pre-Treatment of Pipelines before installations …………………….……….. 16

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4.1.3 Installations ………………………………………………………………………………….. 17

4.2 U.F.G.C …………………………………………………………………………………………….. 18

4.2.1 Electronic Volume Corrector ……………………………………………………….... 20

4.2.2 Types of EVC ……………………………………………………………………………...….. 20

4.3 Operation & Maintenance …………………………………………………………………. 22

4.4 Metering ………………………………………………………………………………..…………. 23

4.4.1 Methods used for Gas Measurement ……………………………………………. 24

4.4.2 Volume Measurement through Gas Meters ………………………………….. 24

4.4.3 Gas Meters ……………………………………………………………………………..……… 25

A. Positive Displacement Meters ……………………………………………… 25

B. Inferential Meters ……………………………………………………………….. 27

4.5 Metering Workshop …………………………………………………………………………. 30

4.5.1 Standardization of domestic meters …………………………………………..… 31

4.5.2 Standardization of industrial meters …………………………………………….. 31

4.6 Corrosion Control ……………………………………………………………………………. 32

4.6.1 Mission………………………………………………………………………………………….... 32

4.6.2 Types of Corrosion …………………………………………………………….………..… 32

4.6.3 Corrosion Protection ……………………………………………………………..…….. 34

COMMENTS………………………………………………………………………………………….… 35

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ACKNOWLEDGEMENT

First of all thanks to ALLAH Almighty. We have taken efforts in this project;

however, it would not have been possible without the kind support and help of

many individuals of SNGPL.

We would like to extend our sincere thanks to all of them. We are highly indebted

to HR department Lahore, and Admin Officer (Fsd) Sir Zahid Rasheed, who

permitted our training program in Faisalabad.

We would like to express our gratitude towards the members of [SNGPL (D) Fsd]

for their kind co-operation. We extend our special regards to the Heads of all the

six departments under whom we completed our training. We thank them for

providing us with necessary information regarding their respective department and

also for their kind support in completing this report.

Our thanks and appreciations also go to our Parents and University Administration

for helping us in availing this Internship program.

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PREFACE

In our six week internship at Sui Northern Gas Pipe Lines Limited (SNGPL),

Faisalabad, we were sent to Distribution Headquarters where we visited different

departments under Distribution and observed their working procedures.

We were taught a lot of new things mainly how to deal with professionals. We got

acquaintance with their professional dealing. We also learned the applications of

Chemical Engineering regarding the flow properties of Natural Gas, the main fluid

of SNGPL.

This report includes a brief introduction to the departments of [SNGPL (D)]. We

have thrown light to their objectives and responsibilities.

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Internship Objectives

To solidify the ideal concepts of

chemical Engineering

To observe and learn managerial

aspects of Professional life

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1. An introduction to SNGPL:

Sui Northern Gas Pipelines Limited (SNGPL) is the largest integrated gas

company, built in 1963.

It has 46 years of experience in operation and maintenance of high-pressure

gas transmission and distribution systems.

Serving more than 3.4 million consumers in North Central Pakistan (Punjab

and Khyber Pakhtoon khwa)

It has undertaken planning, designing and construction of pipelines, both for

itself and other organizations

The distribution activities covering1,624 main towns along with adjoining

villages in Punjab & Khyber Pakhtoon Khwa are organized through 8

regional offices.

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1.1 Vision Statement

To be the leading integrated natural gas provider

To improve the quality of life of our customers

Achieve maximum benefit for our stakeholders

Uninterrupted and environment friendly energy resource.

1.2 Mission Statement

A commitment to deliver natural gas to all door steps in their chosen areas

through continuous expansion of their network, by optimally employing

technological, human and organizational resources, best practices and high

ethical standards.

1.3 SERVICES:

Construction of transmission and distribution pipeline networks

Compressor station design / planning and installation

Project planning and permissions

Preliminary cost and design estimates

Surveying

Mapping

Station automation & control, SCADA

Construction of gas pressure reduction and custody transfer meter stations

1.4 Natural Gas:

Natural gas is found in gaseous form naturally, underground at varying depths,

comprised primarily of methane, natural gas is odorless and colorless. Prior to

distribution, a harmless odorant is added so that any leakage can be easily detected

before an unsafe situation occurs. It is also a

Cleanest burning fuel, as it emits only CO2 and water vapor.

It is lighter than air and dissipates easily into atmosphere.

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2. SNGPL’S Distribution Department:

SNGPL's Distribution department is responsible for the safe, reliable and efficient

distribution of natural gas through the utility pipes to customers,

(Domestic/Commercial/Industrial/Special Domestic). The department has

Its own development, planning and metering staff

8 regional offices

3.35M domestic consumers

52,242 Commercial consumers

5953 Industrial consumers

Consists of 67,449 KM of pipeline.

2.1 Operations of distribution

Physical connection

Lay down service lines

Pipe fitting

Coat and wrap materials

Consumer meter station

2.2 Departments of SNGPL [D]:

Here is the list of Departments we visited during our training

Development

U.F.G.C

Operation/Maintenance

Metering

Metering workshop

Corrosion

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3. GENEREL

3.1 Gas Network:

Gas well ----------> Separation ----------- > Purification ------------ > Transmission-

Lines (1000-3000 psi) ----200km----- > Compressor Station ---------- > SMS (100-

200 psi) ------------- > Distribution Lines (100-200 psi) ------------- > TBS --------- >

DRS ---------- > CMS (30-35 psi)

3.2 Important Terms:

Distribution System

A general term applied to all Company owned pipelines from the outlet of SMSs to

the outlet of CMSs and all pressure regulation stations, C.P. stations, metering

stations located on these.

Transmission and transmission pressure

The transportation of gas from the gas fields to various centers of distribution

including all pipeline operations and maintenance work connected with it. All

pressures in excess of 275 psig (maximum distribution pressure) will be termed as

Transmission pressure.

Sales Meter Station (SMS)

These are installations designed to reduce/control the pressure of gas and measure

the quantity of gas being fed into a distribution system. It is the Terminal point

of a Transmission main.

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Consumer Metering Station (CMS)

It is the installation designed to reduce/control the pressure of gas and measure the

quantity of gas being fed into a consumer’s houseline. These are Terminal points

of the Company’s distribution system

Supply Main S/M

These are gas mains installed for the purpose of transporting gas from a source of

supply (SMS or another supply main) to one or more large volume consumers or to

interconnect supply mains. Operation pressure limits are 60-150 psig.

Feeder Mains F/M

These are gas mains installed for the purpose of distribution of gas within a town.

They feed gas into various District Main Systems directly or through a District

Regulator Station (DRS). Operating pressure limits are 30-60 psig.

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4. Working of Distributions’ Departments

4.1 Development

Planning & Development department is responsible for Survey & Design,

Geographical Information System (GIS), Mapping and Contracts. AutoCAD

release 2008 software is used as drafting tool.

Planning, Survey and design of new transmission pipeline system,

distribution supply mains and augmentation of existing transmission /

distribution system.

Development of Geographical information System (GIS) maps of natural gas

distribution network and transmission pipelines.

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The jobs of Development department are given below

4.1.1 Sizing

Gas Mains are sized for the gas loads provided by the Sales Department

using standard gas Flow Formulas, and the standard pressure drops for

various categories of mains. 1”, 2”, 4”, 6”, 8”, 10”, 12”, 14”, 16” nominal

dia, will be used.

Load estimation

To estimate the load for a CMS standard measures are used:

For domestic line 1 house = 35 ft3

1 commercial (industries and CNG) = 150 ft3

if there are 100 houses in a town then the load will be estimated as;

= 3.5 mcf

Where,

Mcf = (thousand cubic feet of gas)

SNGPL defines one cu-ft as a volume of gas which occupies 1 cuft3 space at a

pressure of 14.65 psia and 60ºF “called base condition”.

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4.1.2 Pre-Treatment Before Installations of Pipe Lines

Cleaning of pipe

Prior to installations, Pipe surface should be free from all loose mill scale,

welding residue, corrosion products, dirt oil, grease, old coatings, paint,

moisture and other foreign materials.

Cleaning is done either manually by using wire brushes or by sand blasting

machine.

Priming

Pipeline primer shall be applied immediately after the cleaning of the pipe

surface just prior to the coating wrapping.

The pipe surface shall be dry at the time the primer is applied.

Primer may be applied by spray type or brush.

Welding

Welding shall be carried out on the pipe placed in a fixed horizontal

position.

Proper night cap shall be installed on the welded pipe lengths on the close of

the work at site daily.

Test of piping for tightness

All distribution lines should be tested with air at 1.5 time the maximum

operating pressure of the line i.e.

o Supply main to be tested at 250 psig (op pressure is 150 psig)

o Distribution lines to be tested at 100 psig (op pressure is 60psig)

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After successful completion of the test, the lines shall be purged with air for

removal of any foreign material.

Before introduction of gas a slug of inert gas (N2 or CO2) shall be introduced

into the pipe to avoid formation of explosive air gas mixture.

Commissioning

Before turning on gas into piping, all openings from which gas can escape should

be closed. Immediately after turning gas into piping the system shall be checked as

follows: -

Checking for leakage can be done by carefully watching the test dial of the

meter with test hand on the upstroke for a sufficient length of time when it

should NOT indicate any movement.

If the houseline test proves to be O.K. then the piping shall be purged and a

small gas burner lighted on it. If the meter dial hand does not move nor the

meter does not register flow of gas through the meter then the meter is

defective and should be replaced.

4.1.3 Installations

Home line installations are done at Low Pressure (pressure in homes is 1

or less than 1 psi)

Whereas Industrial/Commercial installations are done at High Pressure

e.g.

o Industries (40-50 psi)

o CNG stations (20-35 psi)

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4.2 U.F.G.C

U.F.G.C stands for Unaccounted for Gas Control, it is the loss of gas which can

be stated as

U.F.G = Purchased gas - sold gas

This department deals with the possible control over the losses of Natural Gas,

Which are mainly caused by:

i. Leakages

ii. Under Billing

iii. Theft

i. Leakages

Leakage is the action of unmeasured gas passing from a

Transmission/distribution system to the outside atmosphere. Leaks can occur

on pipe walls at welded, screwed or flanged connections, at couplings and at

valve stems.

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Gas leakages are detected by its odor (the smell of added odorant). Leakages

are caused when the pipe joints are damaged or there are holes on pipe

surface due to the pressure of sewerage pipes lying along or above them or

when they are corroded or eroded.

Pipe replacements or electrical welding are done to over come these

leakages.

ii. Under Billing

This type of loss is caused by error in noting down the reading of meters,

owing to the un-awareness of meter readers, or some technical error in

mechanical counter of the meter.

These losses can be minimized by arranging proper training programs for the

meter readers, and by replacing the suspected meters.

iii. Theft

Theft is the major and an increasing cause of Gas losses in many regions

of the country. The common way of gas theft is tempering of meters.

Here are listed some of the theft anomalies through which a consumer

can be suspected, these are:

Miss match between the reading of EVC (Electronic Volume Corrector) and

mechanical counter of the meter.

Non-zero fault volume (it is the volume on which T,P factors are not

accommodated by disturbing the T,P probes of EVC)

Running load of consumer is more than the reported load to company.

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Sealed wires of meters in a non-rigid of flexible state.

Miss match between last 3-digits of Seal on meter and Insert.

Lose wires passing through oil plugs of meters as these places are most

likely to use for tempering of meters.

The CMS inside the consumer premises is also suspected.

4.2.1 Electronic Volume Corrector (EVC)

Since Natural Gas is a compressible fluid its volume is a function of temperature

and pressure.

Electronic volume corrector (EVC) allows for compensation of live pressure,

temperature and super-compressibility. EVC is actually a dedicated microcomputer

that takes metered volume in the form of pulses and uses transducers to measure

gas pressure and temperature and hence corrects the metered volume. The basic

design of the EVC allows for very accurate measurements and long term

reliability. It has some inherent qualities:

Conversion error of 0.5% or better

Large, easy to read dual display eliminates need for confusing parameter

codes by displaying numeric value along with the associated description

Mechanical backup counter

Gauge pressure displayed

4.2.2 Types of EVC

Dresser (PTZ or IMC)

EL-Gas (mini elcor, elcor 1, elcor 2)

Mercury

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Dresser and EL-gas are more common, their hourly, weekly and monthly data can

be retrieved on laptops by connecting data cable to data output port of EVC and

thus analyzed for suspected consumers to check and report for gas thefts.

In addition to this, on industrial CMS’s solar panels are installed which provide

online monitoring of EVC data through GPRS.

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4.3 OPERATION & MAINTENANCE

O & M Department deals with the rectification of customer’s complaints on daily

basis.

Department has its welding section and welding teams which deals with

emergency rectification of complaints

Usually the complaints are about leakages (on or underground leakages)

Laser detectors are used to identify underground leakages

Meter replacements and disconnection of suspected meters is also done

Maintenance of valves , shifting of meters and service lines form old lines to

now lines is also dealt

Help line number is 1199

The minimum rectification limit is 24 hours.

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4.4 METERING

Metering Department is responsible for accurate measurement of gas,

operation and maintenance of all metering and regulating stations having

following major scope of work.

Operation and maintenance of instruments like Valves, Regulators, Relief

Valves, Electronic Volume Corrector, Meters etc.

Calibration of Instruments such as Pressure / Temperature Recorders,

Calorimeters, Gauges etc.

Design of metering and Regulating Stations

Schedule meter replacement

Operation and Augmentation of Distribution network

Repair of all types of meters at Central and Regional meter shops and

generation of impartial and accurate Meter Inspection Report

WHY THE GAS SHOULD BE MEASURED?

To know the volume of gas being consumed by each consumer for the

purpose of billing (revenue collection)

Standardize the measurement for each customer, everybody should be

treated equally

For the reconciliation of the system

To minimize the measurement losses

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4.4.1 Methods Used for Gas Measurement

Fixed factor measurement

A very precise regulator is installed upstream of the meter.

High Pressure Measurement

By the use of volume correctors or P/T recorders.

4.4.2 Volume Measurement through Gas Meters

For the continuous measurement, rate of flow is determined by time period

in which the volume has passed, Gas meters are used for this purpose.

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4.4.3 Gas Meters

A. Positive Displacement Meters

These meters measures the known volume of gas in the fixed chamber and

displaces this volume. The number of fixed volumes displaced is calibrated to

provide volume of gas passed through the meter on its index. These meters have

deformable chamber walls in which volume of gas fills and displaces out. Their

types are:

i. Diaphragm Meters

These are most common meters.

Within the meter there are two or more chambers

formed by movable diaphragms.

With the gas flow directed by internal valves, the

chambers alternately fill and expel gas, producing a

near continuous flow through the meter.

As the diaphragms expand and contract, levers

connected to cranks convert the linear motion of the

diaphragms into rotary motion of a crank shaft

which serves as the primary flow element.

This shaft can drive a counter mechanism or it can

produce electrical pulses for a flow computer.

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ii. Rotary Meters

Rotary meters are highly machined precision instruments

capable of handling higher volumes and pressures than

diaphragm meters.

Within the meter, there are, two figure "8" shaped lobes, the

rotors (also known as impellers or pistons), spin in precise

alignment.

With each turn, they move a specific quantity of gas through

the meter.

The rotational movement of the crank shaft serves as a primary flow element

and may produce electrical pulses for a flow computer or may drive an

odometer-like counter.

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B. Inferential Meters

These meters do not directly measure the volume of gas but uses some property of

fluid flow to inference the gas volume. Usually velocity of fluid stream is

measured through the fixed Area and volume is computed by using formula

Q = V×A

i. Turbine meters

Gas turbine meters are velocity sensing devices

A turbine meter introduces a restriction (called a nose cone) of known cross-

sectional area into the gas stream

The direction of flow through the meter is parallel to a turbine rotor axis

The speed of rotation of the turbine rotor is nominally proportional to the

rate of flow

Gas volumes are inferred from the rotations of the turbine rotor

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ii. Orifice Meters

An orifice gas meter consists of a straight length of pipe inside which a

precisely known orifice creates a pressure drop, thereby affecting the

flow.

Orifice meters infer the rate of gas flow by measuring the pressure

difference across a deliberately designed and installed flow disturbance.

The gas static pressure, density, viscosity, and temperature must be

measured or known in addition to the differential pressure for the meter to

accurately measure the fluid.

Orifice meters often do not handle a large range of flow rates.

However, they are easy to field-service and have no moving parts.

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iii. Sonic Meters

The Sonic meters are based on ultrasonic and electronic platform.

They are more complex than meters that are purely mechanical, as they

require significant signal processing and computation capabilities.

Ultrasonic meters measure the speed of gas

movement by measuring the speed at which

sound travels in the gaseous medium within

the pipe.

Ultrasonic meters are high-cost and work best

with no liquids present at all in the measured

gas.

Primarily used in high-flow, high-pressure

applications such as utility pipeline meter

stations, where the gas is always dry and lean.

Following are also the jobs of metering department

Obtaining copy of program of checking, inspecting, and flow proving of meters

installed at meter stations, from workshop and to check a record maintained for

Meter stations.

Meters.

Valves.

Filters.

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4.5 Metering workshop

The central metering workshop is situated in Lahore; however, on regional

level there are three Metering Workshops at Islamabad, Multan and

Faisalabad.

The Regional Workshop performs check over domestic and industrial meters

(16M capacity) only and on the following lines

Internal Tampering, Reparability checking

Flow Proving

Flow Chart for Checking/Repairing of Meters

Receipt of Meters

Repairing/Overhauling

Repair Card

Leakage Testing

Flow Proving

If not within Accuracy

Repairable

Meter Seal Checking

If not Repairable

Within Accuracy

Repair Area

Painting

Dispatch Area

Initiate Scrapping

Resealing & Dispatching

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There are two types of meters which are used at domestic level.

i. Remus meters

ii. G 4 meters

Repairing of Remus meter is easy, but in the case of error in a G4 meter the whole

internal body needs to be replaced.

4.5.1 Standardization of a Domestic Meter

Flow proving is employed for the standardization of new and faulty meters

Five meters in series are connected with the standard meter (calibrated)

A known flow of Air is passed through standard meter and then in series to

all the connected meters and the reading of every meter is noted down

A tolerance of +2 is acceptable between the reading of a testing and

standard meter

leakage is checked by putting all the meters in a soapy water bath, if any

kind of leakage is present then bubbles are produced in water.

4.5.2 Standardization of an Industrial Meter

In case of industrial meters we can standardized them by using flow proving

machine.

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4.6 Corrosion Control

Corrosion is the electrochemical oxidation of metals in reaction with an

oxidant such as oxygen. It can be concentrated locally to form a pit or crack or

it can expand across the whole surface.

The jobs of corrosion department is

To protect all company underground pipeline from corrosion

To ensure optimal use of utilization of pipelines

To enable continuous, safe and reliable delivery of Natural Gas

To avoid any adverse effect on environment, people and assets

4.6.1 Mission

To protect pipeline through Cathodic Protection (CP)

To prevent, detect, mitigate corrosion and assessment of pipeline integrity

by applying best engineering practices

To maintain safe and high technical standards to ensure continuous and

reliable delivery

4.6.2 Types of corrosion

Galvanic Corrosion

Pitting Corrosion

Crevice Corrosion

High temperature Corrosion

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Galvanic corrosion

Galvanic corrosion is an electrochemical process in which one metal corrodes

preferentially to another when both metals are in electrical contact and immersed

in an electrolyte.

One way is to electrically insulate the two metals from each other. Unless

they are in electrical contact, there can be no galvanic couple set up. This

can be done using plastic or another insulator to separate pipelines of

different metals.

Pitting Corrosion

Pitting corrosion, or pitting, is a form of extremely localized corrosion that leads to

the creation of small holes in the metal.

The driving power for pitting corrosion is the depassivation of a small area, which

becomes anodic while an unknown but potentially vast area becomes cathodic,

leading to very localized galvanic corrosion. The corrosion penetrates the mass of

the metal, with limited diffusion of ions

Crevice Corrosion

Crevice corrosion is a corrosion occurring in spaces to which the access of the

working fluid from the environment is limited. These spaces are generally called

crevices. Examples of crevices are gaps and contact areas between parts, under

gaskets or seals

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4.6.3 Corrosion Protection

Surface treatments

Reactive coatings

Cathodic protection

Surface treatments

Plating, painting, and the application of enamel are the most common anti-

corrosion treatments.

They work by providing a barrier of corrosion-resistant material between the

damaging environment and the structural material.

Reactive coatings

If the environment is controlled corrosion inhibitors can often be added to it. These

form an electrically insulating and/or chemically impermeable coating on exposed

metal surfaces, to suppress electrochemical reactions. Such methods obviously

make the system less sensitive to scratches or defects in the coating, since extra

inhibitors can be made available wherever metal becomes exposed.

Cathodic protection

Cathodic protection (CP) is a technique to control the corrosion of a metal surface

by making that surface the cathode of an electrochemical cell. Cathodic protection

systems are most commonly used to protect steel, water, and fuel pipelines and

tanks; steel pier piles, ships, and offshore oil platforms.

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COMMENTS

The experience at SNGPL distribution headquarters was very delightful. We were

taught managerial aspects and also learnt the engineering applications.

But we want to make a humble request to SNGPL administrations to accommodate

the students in Transmission Headquarters where they will be able to learn

practical applications of fluid flow equipments like Compressors turbine etc, their

major field of interest.

With this note we once again pay our regards to SNGPL and wish it a BEST

TOMORROW rather the better.