Department of Neurosurgery

8/6/2019 Department of Neurosurgery

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AN OVERVIEW OF

VISAKHAPATNAM STEEL PLANT

Visakhapatnam Steel Plant, the first coastal-based steel plan t ofIndia is located 16km south east of destiny i.e., Visakhapatnam.

Bestowed with technologies, VSP has an installed capacity of 3 million

tones per annum of liquid steel 2.56 million tones of saleable steel. At

VSP there is emphasis on total automation, seamless integration andefficient up gradation, which result in wide range of long and structural

products to meet stringent demands of discerning customers within India

and abroad.

VSP products meet exalting International quality standards such

as JIS, DIN, BIS, BS, etc.VSP has the distinction to be the first

integrated steel plant in India to become a fully ISO-9001 certified

company. The certificate covers systems of all operational, maintenance,services units. Besides purchase systems, Training and marketing

functions spreading over 4 regional marketing offices and 22 stockyards

located all over the country.

VSP by successfully installing & operating efficiently Rs.460crore worth of pollution control and environment control equipments

and converting the barren landscape by planting more than 3 million

plants has made steel plant township and the surrounding areas into aheaven of lush greenery. This has made Steel Township a greater,

cleaner and cooler place, which can boast of 3 to 4 degrees lesser

temperature even in the peak summer as compared to Visakhapatnam

city.


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VSP exports pig iron & steel products to Srilanka, Myanmar,

Nepal, Middle East, USA & South East (Pig Iron). RINL-VSP was

awarded Star Trading House status during 1997-2000. Having

established a fairly dependable export market, VSP plans to make a

continuous presence in the export market.

Having a total manpower of about 17250 VSP has envisaged a

labour productivity of not less than 230 tones per man-year of liquid

steel, which is the best in the country and comparable with the

international levels.

BACKGROUND:

With a view to give impetus to industrial growth and to meet the

inspirations of the people from south India, Government of India

decided to establish Integral steel plants in public sectors at

Visakhapatnam(AP) and Hospet (Karnataka) besides a special steel

plant at Salem(Tamilnadu). The announcement was made in the

parliament on 17th April 1970 by the prime minister of India late Smt.

Indira Gandhi.

A site was selected near balacheruvu creek near Visakhapatnam

city by a committee set up for the purpose, keeping in view the

topographical features, greater availability of land proximity to a future

port. The foundation stone for the plant was laid down by late Smt.

Indira Gandhi on 20-01-1971.

Seeds were thus sown for the construction of a modern

sophisticated Steel Plant having 3.4 million tones annual capacity. Anagreement was between Governments of India and erstwhile and Soviet

Union on June 12th 1979 for setting an integrated Steel Plant to produce

structural and long products on the basis of detailed project prepared by

Dr. M.N. Dastur Company was submitted in Nov.1980 to Govt. of India.


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The construction of plant started on 2nd feb.1982.Govt of India on

18th feb.1982 formed a new company called Rashtriya Ispat Nigam

Limited (RINL) and transferred the responsibility of constructing,

commissioning and operating the plant at Visakhapatnam from Steel

Authority of India ltd. to RINL.

Due to poor resource availability, the plant construction could not

keep pace with the plans, which led to appreciable revision of the plant

cost. In the view of the critical fund situation, and need to check further

increase in the plant costs, a rationalized concept was approved which

was to cost Rs.6849 crores on 4th quarter of 1988.

The rationalized concept was based on obtaining the maximumoutput from the equipments already installed, planned/ordered for

procurement and achieving higher levels of operational efficiency and

labour productivity. Thus, the plant capacity was limited to 3 million

tones of liquid steel per annum.

The availability of resources were continued to be lower than

what was planned and this further delayed the competition of the

construction of the plant. Finally all the units were constructed andcommissioned by July 1992 at a cost of Rs.8529crores. The plant was

formally dedicated to the nation on 1st august 1992 by the prime minister

of India Sri P.V Narsimha Rao.

VSP has already crossed many milestones in the fields of

production, productivity and exports. Coke rate of order 543 Kg/ton of

Hot metal, average converter life of 649 heats an average of 11.5 heats

per sequence in continuous bloom caster. Specific energy consumptionof 7.51G kal/ton of liquid steel, a specific refractory consumption of

15.2 kg and labour productivity of 192 ton/man years are some of the

peaks achieved(during the year 1999-2000) in pursuit of excellence.


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AIR SEPERATION PLANT

Air separation plant is one of the major auxiliary units and is

adjusted to meet the maximum daily demand of gaseous Oxygen,

gaseous Nitrogen and gaseous Argon. The plant has the provision for the

production of liquid Nitrogen and liquid Oxygen for storage and

utilization during the period of shutdown of the plant. The plant has

three air separation units, which produce 500 tones/day of

Oxygen(supplied by M/S B.H.P.V).

MAJOR CONSUMERS:

Total requirements of Oxygen, Nitrogen and Argon all over theplant for three million tones stage is 24.248 Nm3/hr and 32 Nm3/hr

respectively. Out of this Steel Melting Shop(SMS) requires 97.3% of

Oxygen for LD converters blowing and LD vessel heating. 65.47% of

Nitrogen produced is consumed by Blast Furnace concasting department

requirement of Argon for homogenization of steel is 93.75%.The basic principle is separation of main constituents of air i.e.

Oxygen(Boiling Point of -182.8 degrees centigrade at 1atm pressure)

and Nitrogen(Boililg Point of 195.7 degrees centigrade at 1 atm

pressure) that is carried out by liquefying the air and separating by

utilizing the boiling point difference for distillation.

BRIEF PROCESS:

Air is sucked from the atmosphere through a pulse type filter

where the dust is removed and then compressed in an air compressor to

7.4KSCA(kg per square cm absolute). This air is precooled in air water

tower to 10 degrees centigrade and sent to purification unit for removal

of moisture, carbon dioxide and other hydrocarbons.


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The purified air passes through the main heat exchanger where it is

cooled to its dew point, currently with the outgoing product i.e. Oxygen,

Nitrogen and waste Nitrogen from the rectification column. A part of air

is taken at an intermediate point and expanded in an expansion turbine to

provide necessary cold to compensate the thermal losses of the system.

The air from the exchangers will be sent to distillation system, which

separates air into Oxygen, Nitrogen and Argon.

For the production of Argon, a gaseous flow is picked at a suitable

point in the upper column of the distillation system(where Argon

contents are maximum) and sent to crude Argon rectification column to

produce crude Oxygen containing 2-3% Oxygen and small amount of

Nitrogen as impurities. Oxygen is separated in a warm Argon

purification unit where Oxygen is reacted with hydrogen in the presence

of a palladium catalyst. Hydrogen required will be taken from water

electrolysis plant(capacity 30 Nm3/hr). Nitrogen is separated by

distillation in pure Argon column.

TABLE:

Gaseous Mode Mixed Mode

Gas Nm3/hr Purity Gas(Nm3/hr) Liquid

(Nm3/hr)

Oxygen 148000 99.5% 12750 875

Nitrogen 296000 99.9% 25500 1000

Argon 100 99.9% -------- 100


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STORAGE AND DISTRIBUTION:

Gaseous Oxygen and Nitrogen from cold box is compressed to

40KSCA, 10KSCA respectively by centrifugal compressors and

supplied directly to the consumers by pipelines. The liquid Oxygen and

Nitrogen will be stored in storage tanks and pumped to 40KSCA by

centrifugal pumps and vaporized by water bath type with steam injection

and supplied to consumers at the time of emergency. Liquid Argon from

cold box is collected in the liquid Argon tanks and cold converters. From

cold converters liquid Argon is vaporized in atmospheric vaporizers and

supplied to con casting department at 7 KSCA.

CYLINDER FILLING STATION:

Liquid Oxygen, Nitrogen and Argon will be pumped by

reciprocating pumps to a pressure of 165KSCA, vaporized, filled and

delivery into cylinders through manifolds of 4, 2, 2 respectively.

GASEOUS STORAGE SYSTEM:

Gaseous Oxygen from the storage will be stored in 8 numbers ifbuffer vessels near SMS (Steel Melt Shop) of 100m3 water volume at

40KSCA. This pressure is reduced to 18KSCG and supplied to SMS.

Gaseous Oxygen is stored near ASP in 3 numbers of 100m3

water volume buffer vessels and pressure is reduced to 12-18KSCG and

supplied for autogenic needs all over the plant.

Gaseous Nitrogen is stored in 6 numbers of buffer vessels of

125m3 water volume of 40KSCG, 2 numbers buffer vessels of 100 m3water volume at 40KSCG for emergency needs of Blast Furnace.

In addition, Nitrogen storage tanks are provided at

desulphurization plant and SMS gas cleaning plant.


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REQUIREMENTS:

ELECTRICITY:

Electric power requirements of ASP are set by LBSS-2. Total power requirement of ASP at 3 million tones stage is 64MW

approximately. Total connected load is 123.7MVA.

COOLING WATER:

There is a closed cycle cooling water system in ASP wherecooling water at 36 degree centigrade is drawn from pump house-14,

which is used as a cooling medium for gas and oil coolers of

compressors and expansion turbine and air pre-cooling system. The hot

water at 45 degree centigrade is returned back to cooling tower for

cooling at 36 degree centigrade.

CHILLED WATER:

Chilled water is taken from chilled water plant and is used ascooling medium in air-conditioning and ventilation systems.

STEAM:

Steam is available near the battle limits at 5-12KSCA(MTN)

for regeneration of absorbers, vaporization of liquids, deriming of

heaters etc.


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PUMP HOUSE:4 pumps of each 3500m3/hr capacity and discharge pressure of

3.5 kg/cm2 are provided to pump the cooled from cooling water for

ASP.

COOLING TOWER:

There are 5 cells of cooling towers and total water flow rate is

12000 m3/hr warm water from different units will be coming back at 2.5

kg/cm2 and cooled in cooling water tower.

DERIMING HEATERS:

2 deriming heaters are provided for warming up of the plant atthe time of shut down and defrosting at the time of leakage if any.

INTRODUCTION TO AIR COMPRESSORS


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The compressors may be classified as follows:

(A) According to design and principle of operation:

There are two basic types:1. Positive Displacement compressors.

2. Non-positive or steady flow compressors.

Positive displacement compressors are further classified as

reciprocating compressors and rotary compressor. In positive

displacement compressors the fluid is prevented by a solid boundary.

Non-positive compressors are the rotary compressors of centrifugal

and axial flow design. In these compressors the fluid is not contained by

solid boundaries but is continuously in a steady flow through the

machine undergoing changes in pressure primarily by means of dynamic

effects.

(A) According to the number of stages:

These are further classified as

1. Single stage compressor : delivery pressure upto 5 bar.

2. Double stage compressor : delivery pressure from 5 to 35 bar.

3. Three stage compressor : delivery pressure from 35 to 85 bar.

4. Fourth stage compressor : delivery pressure above 85 bar.

(A) According to the pressure limits:

Compressors are also classified as per the delivery pressure:


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1.Low pressure compressor:delivery pressure upto 1 bar

2.Medium pressure compressor:delivery pressure from 1 to 8 bars

3. High pressure compressor:delivery pressure from 8 to 10 bars

4.Super high pressure compressor:delivery pressure above 10 bars.

(B) According to the capacity:

Compressors are also classified according to the volume of air

delivered per unit time. They are:

1.Low capacity compressor : volume delivery 0.15m3/s pr less.

2.Medium capacity compressor : volume delivery 0.15 to 5 m3/s.

3.High capacity compressor : volume delivery above 5 m3/s.

(C) According to power drives:

1. Direct drives.

2. Belt drives.

3. Chain drives.

(D) According to nature of installation:

1. Portable

2. Semi-fixed

3. Fixed

(A) According to moving parts:


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1. Reciprocating

2. Centrifugal

3. Rotary

(A) According to number of power cylinders:

1. Single cylinder

2. Multi cylinder

(A) According to the method of cooling:

1. Air cooled

2. Water cooled

(A) According to number of air cylinders:

1. Simplex

2. Duplex

3. Triplex

CENTRIFUGAL COMPRESSOR:

Centrifugal compressor is a non positive or steady flow rotary

compressor. A centrifugal compressor consists of an impeller rotating at

high speed (20000-30000rpm). The impeller consists of a disc on which

radial blades are attached. The air enters the impeller eye and flows


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radially outward with increasing pressure and temperature. In impeller a

static pressure of air increases from eye to the tip in order to provide the

centripetal force on the air. From the impeller the air enters a diffuser,

which provides a gradually increasing area to convert velocity energy to

pressure energy.

In Single stage centrifugal compressors a pressure ratio of 4:1

can be obtained. Pressure in multi stage compression can go upto 10 bar.

The impeller may be a single sided or double sided. In double sided

impeller suction takes place from both sides.

The figure shows the schematic diagram of centrifugal

compressor.

Components of a simple centrifugal compressor

A simple centrifugal compressor has the following four components: inlet, impeller/rotor,

diffuser, and collector. If you look carefully at Figure_3.1 you will be able to identify each

of these 4 components of the flow path. With respect to the figure, the flow (working

gas) enters the centrifugal impeller axially from right to left. As a result of the impeller

rotating clockwise when looking downstream into the compressor, the flow will pass

through the volute's discharge cone moving away from the figure's viewer.


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Figure_3.1 Cut-away view of aturbo- chargershowing the centrifugal compressor (blue) on the

right end of the rotor

Inlet

The inlet to a centrifugal compressor is typically a simple pipe. It may include features

such as a valve, stationary vanes/airfoils (used to help swirl the flow) and both pressure

and temperature instrumentation. All of these additional devices have important uses in

the control of the centrifugal compressor.

Centrifugal impeller

The key component that makes a compressor centrifugal is the centrifugal impeller. It is

the impeller's rotating set of vanes (or blades) that gradually raises the energy of the

working gas. This is identical to an axial compressor with the exception that the gases

can reach higher velocities and energy levels through the impeller's increasing radius. In

many modern high-efficiency centrifugal compressors the gas exiting the impeller is

traveling near the speed of sound.

Impellers are designed in many configurations including "open" (visible blades),

"covered or shrouded", "with splitters" (every other inducer removed) and "w/o splitters"

(all full blades). Figure 3.1 show open impellers with splitters. Most modern high

efficiency impellers use "backsweep" in the blade shape.

Eulers pump and turbine equation plays an important role in understanding impeller

performance.

Diffuser
http://en.wikipedia.org/wiki/Turbo-chargerhttp://en.wikipedia.org/wiki/Turbo-chargerhttp://en.wikipedia.org/wiki/File:Turbocharger.jpghttp://en.wikipedia.org/wiki/Turbo-charger


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The next key component to the simple centrifugal compressor is the

diffuser. Downstream of the impeller in the flow path, it is the diffuser's responsibility to

convert the kinetic energy (high velocity) of the gas into pressure by gradually slowing

(diffusing) the gas velocity. Diffusers can be vaneless, vaned or an alternating

combination. High efficiency vaned diffusers are also designed over a wide range of

solidities from less than 1 to over 4. Hybrid versions of vaned diffusers include: wedge,

channel, pipe and pipe diffusers. There are turbocharger applications that benefit by

incorporating no diffuser.

Bernoulli's fluid dynamic principal plays and important role in understanding diffuser

performance.

Collector

The collector of a centrifugal compressor can take many shapes and forms. When thediffuser discharges into a large empty chamber the centrifugal compressors collector

may be referred to as a Plenum. When the diffuser discharges into a device that looks

somewhat like a snail shell, bull's horn or a French horn, the collector is likely to be

referred to as a volute or scroll. As the name implies, a collectors purpose is to gather

the flow from the diffuser discharge annulus and deliver this flow to a downstream pipe.

Either the collector or the pipe may also contain valves and instrumentation to control

the compressor. For example, a turbocharger blow-off valve.

OXYGEN COMPRESSOR

INTRODUCTION:
http://en.wikipedia.org/wiki/Bernoulli's_principlehttp://en.wikipedia.org/wiki/Bernoulli's_principle


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To ensure uninterrupted supply of Oxygen to the consumers

there are six numbers of oxygen compressors in air separation plant.

These oxygen compressors are supplied by M/S. SULZER,

SWITZERLAND & erected and commissioned by M/S. BHPV Ltd.

DESCRIPTION:

Oxygen compressor is a large centrifugal compressor, which

operates on the combination of the following systems.

Power supply:

Power is supplied by main motor manufactured by BHEL ofrated power 3200Kw and of supply voltage of 11000 +/- 10%.

Bearing sealing system/pneumatic valves:

This is system provided for easy supply of air 6 atm and 300C

to all pneumatic operated valves and to seal the bearing pedestal.

Cooling water systems:

Cooling water of 3.5 atm and 360C is supplied to cool down

the lube oil, cool down the air of the driving motor and to cool

down the Oxygen after the individual compressor stages.

Lubricating oil systems:

This system is included to lubricate the bearing of the driving

motor, gear and compressor. This lubricating oil system includes

oil tank, oil mist fan, main oil pump, oil coolers & oil filters.

LP & HP compressor:

This compressor train consists of two compressors namely

LP & HP compressors. LP compressor is a two stage compressorand HP compressor is a three stage compressor. These are

manufactured by SULZER company.

Gear box:


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Gear box is used between the motor and the LP compressor

to transfer the motion from one position to the other. It increases

the speed of the rotor from the power given by the shaft of the

motor. It is manufactured by MAAG.

TECHNICAL SPECIFICATIONS:

LP COMPRESSOR:

Manufacturer : SULZER ESCHER WYSS.

Type : RZ 35 2 + 2

OPERATING CONDITIONS:

100% 10% UNITS

FLOW 15000 16500 Nm3/hr

SUCTION

PRESSURE

1.5 1.5 Atm

SUCTION

TEMPERATURE

25 25 0C

DISCHARGE

PRESSURE

40 40 Atm

DISCHARGE

TEMPERATURE

42 42 0C

POWER ATMOTOR

2650 2845 kws


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OIL MIST FAN:

Manufacturer : LUESCIHER

Air flow capacity : 3 m3/min.

Pressure difference : 70 mm WC

OIL TANK:

Manufacturer : SULZER ESCHER WYSS

capacity : 2700lt.

MAIN OIL PUMP:

Manufacturer : ALL WEITER

Type : SNG*210-40

Capacity : 5 atm

Speed : -3315 rpm

AUXILLARY OIL PUMP:

Manufacturer : ALL WEITER

Type : SNH 210 R 4647 WI

Capacity : 412 lit/min

Pressure : 4 atm

TWIN OIL COOLER:

Manufacturer : CALORIFIER

Heat exchanger each element : 120 w

Oil temp in & : 630C


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Out : 500C

Water temp in & : 360C

Out : 41.20C

Oil flow : 333 lit/min

TURBO GEAR:

Manufacturer : MAAG

Type : GN*60

Speed : 1500/16080 rpm

Power : 3200 Kw

TOOTHED COUPLING:

Manufacturer : RENK

Type : ZNX100

Oil Filling : 2.7 litres

MAIN MOTOR:

Manufacturer : BHEL

Rated power : 3200 Kw

Rated current : 219.6 amps

COOLING WATER SYSTEM:

Cooling water temperature inlet : 360C

Outlet : 450CCooling water pressure inlet : 3.5atm


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Outlet : 2.5 atm

Water requirement : 550 lt/min.

MAINTAINANCE OF IMPELLERS

INSPECTION OF IMPELLERS:


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It is advisable to careful check the impellers at the opportunityof any overhaul. The operator is recommended to inform themanufacturer about the check results with indication of the applied testmethods.

1. Sources of Damage:Depending on the operating conditions and on the nature of

the compressed gas, the impeller can be affected in the course oftime, by the following:

Aspired dust, if no, or only insufficient intake filters are installed,or when the filter are badly maintained.

Aspired humidity, originating from coolers or cleaners.

Surface corrosion, caused by: Corrosive liquids aspired together with the handled gas. Condensate, containing chemical pollutants from the ambient

air.

1. General Examination:

Before shutting down the compressor, the vibrations should

be judged. Vibrations can occur by a detoriation of the rotorbalance, caused by unsymmetrical deposition of dirt or by damagesas mentioned before.

Before cleaning the impellers, their surfaces are to bechecked against signs of uneven dirt deposits, which could point tofaults in the impeller surface. Suspicious areas are to be marked andafter cleaning thoroughly investigated.

After cleaning, a chalk mark should be made on one bladeof every impeller. By starting from the chalk marked blade, anaccurate sight check of the whole impeller must be made. Checkalso the shape of the blades at the impeller inlets and compare the

blade thickness with the original dimension.


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On small rotors, the accessibility to the impellers is bad. Itis recommended to carry out the sight by the help of a small mirror,fastened to a stick and electric lighting.

2. Special Checks:

Cast or Welded ImpellersThe following components are to be examined thoroughly:

Blade inlet edges Blade roots along the impeller discs Inlet ring

If a rupture is suspected, the area in question must beground slightly and re-checked. For better recognition of a

possible crack, it is recommended to apply the visiblepenetrate( if the required liquids are available). The besttest method is the magnetic powder test, which isrecommended to apply if a specialist is on site.

Riveted Impellers

The impellers are to be checked against missed rivet heads

or cut-off rivet shafts. Projecting rivets are to be knocked witha light hammer so as to check whether the rivets are broken ornot.

Special care should be taken to the transition pointsbetween blades and rivets. These points are especiallyendangered by electro chemical attacks, caused by corrosiveliquid penetrating into the space between the holes and rivets.Lying in the said space, the concentration of the liquid can

even increase and cause a supplementary source of danger.

The discs are to be checked against incipient fracture inthe surroundings of the rivet holes. In case of doubts, the aforementioned visible penetrant or magnetic powder tests should

be carried out.


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1. Inspection Report:

Faults and damages reveled during inspection shouldreported and if necessary augmented by sketches or photographs. Ifthe checks do not show any problems a corresponding note should

be written.The methods applied when remedying faults should be

described likewise in the report. Inspection for the application of thecack test(penetrant process)

Surface to be inspected must be free from oil, grease, rust

and paint. Apply the red-colored spray penetrant and allow a contact

time of 10-20 minutes. Carefully clean surface, first by wiping with the cloth, then

with liquid dissolvent. The red penetrant will remain behindin eventual cracks, pores and laps.

Ensure that last traces of surplus penetrant have beenremoved and that the surface of the component is dry.

Shake the can of the Developer liquid thoroughly and spray

a thin even film onto the component. Allow developer filmto dry after evaporation, a white porous coat will remain,which sucks the red colored penetrant from the cracks, sothat cracks can be recognized on the white background.

The requirements for maximum performance precludethe use of any method of application other than spraying

brush application is not recommended.

MAINTAINANCE OF VOLUTE CASING

INTRODUCTION:


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Volute casing maintenance is a very important part of theoverhaul of an oxygen compressor plant. Volute casing is the space inthe compressor, which comes in contact with the oxygen gas itself. Any

kind of contamination leads to great losses in the performance and mayalso cause accident. However volute casing is the only place, which getsless contaminated compare to other components.

CLEANING OF VOLUTE CASING:

The method adopted for cleaning volute casing is usuallymechanical cleaning which consists of brushing, sweeping, blowing,scraping, chaining, sand blasting, agitating or otherwise physicallyremoving contaminants from equipment.

Ultrasonic method is also employed for cleaning the volutecasing. This method employs special equipment to agitate the cleaningfluid, usually a solvent, at high frequency to dislodge particles and breakup films.

INSPECTION OF VOLUTE CASING:

Volute casing is very important before correction of thecompressor because any contamination with greases or oils will lead toaccidents.

Two methods are adopted for inspection Direct visual inspection Ultraviolet light inspection

Direct visual inspection:

This method is adopted to verify the cleanliness of casing.Look at or in the casing under bright white light to detect the presence of


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visible grease or oil films and particulate matter such as filings, rest ormill scale.

Ultraviolet light inspection:

It is used in addition to direct visual inspection to detect

common oils or greases. Inspection in darkness subdued light usingultraviolet light of 3200-3800mm wavelengths. If a bluish whiteflorescent screen is present readen the item. This method is also adopted

because most hydrocarbon oils and greases show florescence underviolet light even though they may be invisible under bright light.

CONCLUSION:

Documents

Department of Neurosurgery