ANNEXURE TO TENDER FILE NO: MRPU/NRPP/CAP/7042

1. Description of the ITEM: Centrifugal Blower - 1 No

Technical Specification of Stainless Steel Centrifugal Blowers

1. Scope:

This specification establishes the technical requirements of stainless steel exhaust blower
and motor. The scope of work includes design, manufacture, assembly, inspection, shop
testing and supply of one (1no.) stainless steel blower with base frame, foundation bolts
& nuts, inlet/outlet metallic flexible bellows, counter flanges with bolts, nuts, washers &
gaskets, vibration isolators, flexible/resilient coupling, electric motors and spare parts to
BARC(F) Stores, Kalpakkam, Tamilnadu.

2. Applicable Standards & Codes:

Latest edition of the following codes and standards shall be applicable. In the event of
any conflict between any requirement in this specification and that of the applicable
codes and standards, the governing requirement shall be the more stringent of the two at
the discretion of the purchaser.
BIS: 4894 : Specification for centrifugal fans.
BIS: 1363 & 1367 : Specification for all threaded fasteners.
ISO 2372 : Vibration severity & group classification.
ISO 1940 : Balancing quality requirements.
ASME Sec. V : NDT requirements.
ASME Sec. VIII Div-1 : Code for design of pressure vessels.
ASME Sec. IX : Procedure for welding and welder’s qualifications.

3. General Description:

3.1. All materials used must conform to the applicable standards & codes and must be new &
first class in all respects. Wherever materials are not specified, they shall be properly
selected by the contractor to the best standards followed in the industry for the particular
applications subject to the approval of the purchaser.

3.2. All parts shall be free from flaws & objectionable imperfections and shall be machined
true in workmanship like manner. The units shall be built to the industries highest
standards of quality to ensure maximum mechanical & electrical reliability.

4. Operating Conditions:

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4.1 Site Condition:

(i) Dry Bulb Temperature : 35.0 Deg.C

(ii) Wet Bulb Temperature : 28.9 Deg.C
(iii) Elevation at G.L. : Sea Level

4.2 Services Available at Site:

(i) 415 V + 6%, 50 C/S + 3%, 3 Phase, 3 Wired Grounded A.C.

(ii) 240 V + 6%, 50 C/S + 3%, Single Phase A.C.

5. General Design Requirements:

5.1. The blower shall be of centrifugal type, single stage having backward inclined/curved/
radial tip blade design. The blower shall be SISW, Arrangement-8 (direct drive through
flexible/resilient coupling) with up blast discharge and clockwise direction of rotation.

5.2. The design shall be such as to select blower for optimum static & mechanical efficiency.
The blower shall have stable operation in the range of 20% to 110% of the rated capacity.

5.3. Operating/Rated speed of the blowers shall be less than 3000 rpm. The critical speed of
the blower shall be at least 1.5 times the operating speed.

5.4. The blower shall be suitable for exhaust air at 65 deg.C (Max.) and containing fumes of
nitric acid in low concentration.

5.5. The discharge and inlet of the blowers shall be circular. In case if it is rectangular,
transition piece shall be provided. It shall have suitably drilled flanges for ease of flexible
bellow connections and it shall be rounded off to next higher nominal sizes of standard
pipes and flanges meeting the standards.

6. General Construction Details:

6.1. Material Of Construction ( for blower and spare parts): The material of construction
is as specified below for different parts of the blowers. Material test certificates (physical
& chemical check) of the parts shall be submitted to the purchaser for its review.

Impeller : SS 304L
Casing : SS 304L
Casing Stiffeners/Bracings : SS 304L
Shaft : SS 316
Flexible Bellows : SS 304L / 316L
Suction/Discharge Flanges : SS 304L
Support Housing : Cast Iron
Base Frame : MS Structural Steel, Epoxy painted

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 Shaft Seal : Compatible to Service Fluid
Bearing & it’s Housing : Standard Original FAG/SKF
Hardware (nuts, bolts, washers): Stainless Steel
Gaskets : Neoprene

6.2. Component Specific Requirements:

6.2.1 Blower Casing: The housing shall be fabricated of SS 304L steel plates of minimum 6
mm thickness, accurately cut & formed and continuously welded through out for added
strength and total air tight construction. The casing shall be suitably stiffened by means
of angles/flats of SS 304L material as required. The cut off shall be so designed to give
smooth quiet & efficient performance of air from blower outlet. All bolts /studs welded to
the casing for end cover or stiffening angles support shall be welded from out side with
pad plate. Inside surface of casing shall be smooth without any projections of bolt heads
etc. The casing weldments shall be D.P. tested for root and final passes.

6.2.2 Blower Outlet Orientation: the outlet orientation should be clockwise upblast ( CW 360
as per the orientation chart provided)

6.2.3 Impellers: Impellers shall be both statically & dynamically balanced. Balancing shall be
carried out with impellers mounted on it’s own shaft while maintaining the actual
assembly conditions. The balancing grade shall be Gr.2.5 as per ISO 1940. The impeller
shall be positively locked to the shaft to prevent it from getting loosened. Locking device
shall be amply designed for full force of sudden start and stop. Blades shall be fully
welded to back plate on one side and on other side it will be partially welded and partially
plug welded to the shroud. The minimum thickness of the components are as,

Component Thickness (mm)

Back plate : 3 mm thick
Shroud : 2 mm thick
Blade : 2 mm thick

6.2.4 Shaft: Shaft of the blower shall be of material SS 316 and amply designed to take up the
various torque and bending moments of the total system. It should be well designed with
fillets & radii to take discontinuous stress at various section changes. The shaft shall be
UT tested as per ASTM A-503, 609. Raw material test for checking chemical properties
for shaft material shall be carried out. Shaft shall be DP tested after machining.

6.2.5 Bearings: The bearing of the shaft shall be of anti friction type of original SKF/FAG
make. An integral/monobloc housing for housing two bearings shall be provided.
Bearings selected shall be designed for the life of atleast 1,00,000 hours. Bearing housing
shall rest on machined surface and properly located by dowels.

6.2.6 Shaft Seal: Dry type mechanical shaft seal shall be provided for all the blowers. The seal
material shall be compatible for the service fluid, i.e., air with acidic fumes. The seal

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 shall be of reputed make proven design and shall be approved of by the purchaser.
Preferable makes are Leakproof / Sanmar / Sealoil Seals.

6.2.7 Coupling: Flexible/Resilient couplings of reputed make shall be offered for all the
blowers. The coupling shall be suitable for the operating speed specified and shall
facilitate ease of assembly & maintenance.

6.2.8 Foundation: The purchaser shall provide the concrete foundation. However, all the
vibration isolators, foundation bolts, padding & all necessary hardware will be in the
scope of the supplier. The foundation design and hardware shall be such that it ensures
minimum vibration to the blowers reckoning with local site conditions. Vibration
isolators shall be of commercially available reputed make.

6.2.9 Flexible Bellows: All blowers shall be supplied with a pair of stainless steel bellows
suitable for inlet and outlet connections with counter flanges, nuts and bolts. The material
of construction of bellows shall be SS 304L/316L. Supporting design calculations and
selection for no. of convolutions and thickness shall be furnished to the purchaser. All
blowers shall be supplied with bellows face welded to flanges.

6.2.10 Lifting Provision: Suitable lifting lugs shall be provided with each type of blower for it’s
handling during installation and maintenance as well.

6.2.11 Motors: The prime movers for blowers shall be of squirrel cage type induction motors
with rating suitable to the range of operation as specified. (Refer Annexure-II).

6.2.12 Erection & Maintenance Tools: A set of erection and maintenance tools for each
category of blower shall be supplied along with blowers.

6.3. Fabrication

6.3.1 The work shall be carried out in clean and dust free environment so as to avoid
contamination of stainless steel components.

6.3.2 To achieve the highest reliability of blower manufacturing, latest techniques such as
profile cutting for cutting of impeller shroud plates, low heat welding techniques for
welding of blades to the back plate and shroud etc. shall be employed.

6.4. Welding:

6.4.1 Welding shall be carried out by duly approved procedure and qualified welders as per the
requirements of ASME Sec. IX. Relevant documents shall be submitted to the purchaser
for its review/approval before starting fabrication.

6.4.2 All S.S. welding shall be done by GTAW process with high purity Argon purging and all

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 M.S. welding by manual metallic arc process with coated electrodes. MS to SS welding
shall be carried out by using ER 309 filler wires.

6.4.3 The weldments on impeller and casing shall be subjected to D.P. test for the first and
final pass.

7. General Inspection & Testing Requirements:

7.1. All the blowers shall be tested at supplier’s work prior to their dispatch to site as per the
specified codes/standards. The supplier shall make all the necessary testing set up
required to carryout the tests at their works. The entire test setup & testing procedures
shall be approved of by the purchaser prior to the test.

7.2. Characteristic curves, calculations & technical details shall be furnished for the above.
The blower shall be tested in all cases prior to actual test by the supplier and shall furnish
the details of the test to the purchaser for approval of carrying out of actual test.

7.3. All the blowers shall be carefully examined to determine their compliance with the
specifications with respect to dimensions, materials workmanship, marking and all other
requirements of the specifications. All the internal reports shall be submitted for
purchaser’s review prior to final inspection.

8. Inspection & Testing at Manufacturer’s Works:

8.1. Inspection: The blowers shall be subjected to inspection to cover dimensional accuracy,
material used, workmanship, make and quality of bought out items. The supplier shall
furnish material test certificates (physical & chemical) for purchaser’s review. The
supplier shall also furnish all the relevant test certificates on bought out items.

Stage inspection as per the approved QAP shall be carried out. Supplier shall
keep the purchaser informed about various stages of inspection indicated in QAP.

8.2. Run Test: This test shall be carried out at manufacturer’s work to examine vibration &
noise after assembly. Each blower unit shall be run at various speeds (around operating
speed). The amplitude & frequency of vibration shall be measured with strobes at various
locations on the blowers. Background level of noise (Db) & noise level with blower in
operation shall be recorded to determine the noise level of the blower. Each blower shall
be run continuously for six hours or till the bearing temperature stabilizes. During this
bearing temperatures, motor current, supply voltage etc. shall be monitored.

8.3. Performance Test: The performance test shall be carried out of blower as per IS: 4894.
This test shall be essentially to draw up the blower characteristics to confirm the
performance parameters namely flow capacity vs. head, flow capacity vs. power
consumption, range of stable operation etc. at rated speed. The duration of test shall be
sufficient to demonstrate that the blowers are in first class operating condition. The
performance test shall be witnessed by the purchaser.

Performance test of blowers at 20%, 60% and 110% of rated blower speed shall

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 also be carried out with manufacturer VVVF Drive.

8.4. Leak Test: All the blowers shall be air tested for leakage after complete assembly. This
test shall consist of blanking the ends of the blowers casing, pressurizing the interior to
twice the design static pressure & applying all welded joints with an approved leak
testing soap solution. No leakage shall be allowed.

9. Performance Guarantee:

Supplier shall give performance guarantee for the blower running under the specified
condition and shall replace any part in the event of failure due to design and
manufacturing faults for a minimum period of one year from the date of installation.

10. Documents to be Submitted after Award of Contract:

After receipt of purchase order and before start of fabrication, supplier shall submit
atleast 3 copies of following documents to the purchaser and shall get it approved.

• GA drawing of blower-motor assembly with dimensional details.

• Detailed inspection and QA plan for blowers, motors.
• Detailed inspection and test procedures.
• Detailed manufacturing and delivery schedule.
• Characteristic curve of blowers and motors.
• Details such as material of construction, make, type and specification of bought out
items like bearings, mechanical seal, flexible bellows, coupling etc. and design
information to support the correctness of their selection.

11. Final Documentation:

The supplier shall make a completion document (in bound volume) for each type of
blower assembly and submit 4 copies of the same to the purchaser at the time of delivery.
The document shall include the following:

• As-built drawing of blower-motor assembly.

• Approved inspection and QA plan.
• Approved inspection and test procedures.
• All relevant material test certificates.
• Final inspection and test reports.
• All relevant certificates of bought out items.
• Guarantee certificate.
• Instruction manuals to cover installation, operation, and maintenance for each type of
blower. (The Manual shall include instructions on alignment, lubrication details,
specifications of parts etc.).

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12. Cleaning, Protection and Painting:

All equipments shall be neatly finished in workmanship like manner. All exposed metal
surfaces shall be smooth and free from burrs. Finished surfaces shall be protected against
corrosion and mechanical damage. All steel and cast iron surfaces shall be thoroughly
cleaned to remove mill scales rust etc. Exterior surfaces shall be given one coat of red or
zinc chromate primer and minimum 2 coats of epoxy paint, the color of which shall be
approved by the purchaser. After cleaning all interiors all openings shall be properly
closed with blank flanges caps etc. to prevent entry of water, dirt etc.

13. Packaging & Shipment:

The blower assembly along with motor after final inspection and testing, shall be packed
properly and shipped to WIP Stores, Kalpakkam, Tamilnadu only after obtaining
shipping release from the purchaser or his authorized representative. The supplier shall be
fully responsible for protective measures to ensure the safe delivery of blower’s by this
specification to the site. All the parts shall be packed in boxes and protected to prevent all
possible damage during transportation. The supplier shall consult the representative of the
purchaser to satisfy himself that adequate measures have taken.

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 Annexure-I

Technical Requirements of Blower

1. Blower Characteristics : Centrifugal type (single stage), backward inclined/

curved/radial tip blade with SISW, Arrangement-8.

2. Operating Fluid : Gas containing nitric acid fumes

3. Operating Fluid temperature : 50 Deg. C

4. Blower Performance:

Blower Qty
Sr. Types
Description
No.
T1

1. Capacity (CMH). 175 1 No.

2. Static Pressure (mm. WC). 1000 (Model No: BSP-7.5)

5. Duty : Continuous, Heavy duty

6. Rated/Operating speed (rpm) : Below 3000 rpm

7. Range of Operation : 20 – 110 % of rated Capacity

8. Shaft Seal : Dry type Mechanical Seal (Reputed make)

9. Shaft Bearing : Original FAG/SKF make (Monobloc Housing)

10. Impeller Balancing : As per ISO 1940 Gr. 2.5

11. Vibration Level (RMS Velocity) : As per ISO 2372 (Less than 4.0 mm/sec)

12. Noise Level : Less than 95 dBA

13. Bearing Temperature : Ambient + 50 Deg.C (max.)

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 Annexure-II

Specification of LT Squirrel Cage Induction Motors

1. Scope:

This specification covers technical requirements for the design, manufacture, inspection,
testing and supply of energy efficient squirrel cage induction motors required as prime
movers for and as an integral part of centrifugal type off gas blowers as specified in this
document.

2. Applicable Standards:

Latest Version of the following standards shall be used.

IS – 12615 : Energy efficient 3 phase squirrel cage induction motor.

IS – 325 : Specifications for 3 phase Induction Motors.
IS – 1231 : Dimensions of 3 phase foot mounted induction motor.
IS – 1271 : Thermal evaluation and classification of electrical insulation.
IS- 2253 : Designation for types of construction and mounting arrangement of
rotating electrical machines.
IS – 3202 : Code of Practice for climate proofing of electrical equipment.
IS- 4029 : Guide of testing 3 phase induction motors.
IS- 4691 : Degrees of protection provided by the enclosure for rotating
electrical machinery.
IS-4722 : Rotating Electrical machines.
IS –4728 : Terminal marking and direction of rotation of rotating electrical
machinery.
IS – 4800 : Enameled copper winding wires.
IS – 12075 : Specifications for limits of vibration of the motors.
IS – 12802 : Temperature Rise Measurement of rotating Electrical machines.
IS – 12824 : CBIP Recommendation of Motors.

3. Technical Specifications :

a) Acceptable make : M/s Crompton, M/s ABB,

M/s Siemens.
b) Type of enclosure : T.E.F.C., IP 55 as per IS – 4691.
& degree of protection
c) Type of Duty : Max. Continuous.
d) No. of phases : 3 phase
e) Rated Voltage : 415 V +/- 10%
f) Frequency : 50 Hz.+/- 5%
g) Class of Insulation : F , Temperature rise limited to class B
h) Speed of Revolution : Shall be compatible with Blower.
i) Direction of Rotation : Shall be suitable for bi-directional rotation.

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 j) Earthing : Two nos. of earthing terminals of proper size shall
be provided..
k) Rotor : Squirrel Cage
l) Control of Speed : Variable Voltage Variable Frequency Drive
m) F.L. Starting current : Not exceeding 600 % of FL current ( DOL Starter )
n) Winding : Copper wound.

o) Fault Capacity of System to which motor is to be connected : 35 MVA

p) Motor is driven by VVVF drive which will introduce harmonics. Motor should be
designed to withstand temperature rise due to harmonics. Motor winding shall have 3
nos. of Thermal switches of proven performances to trip motor in case temperature
exceeds preset limit.

q) Rating of motors shall be suitable to the Blowers.

r) Terminal Box shall be of adequate size to accommodate cable one size higher than the
minimum recommended. Shall be possible to change orientation of cable box to suite
condition for entry of cable.

4. Drawings:

4.1 Drawings showing general arrangements, frame, foundation, weight etc shall be
submitted along with the technical specifications of the bid.

4.2 Approved drawings shall be obtained from the purchaser prior to the fabrication.

5. Inspection & Testing:

5.1 The supplier shall perform acceptance & routine tests for all the motors and type test
for one motor of each rating as per latest version of IS – 325 & IS – 4029 at the motor
manufacturer’s works. The test reports shall be submitted to the Purchaser for its review
before dispatch.

5.2 The supplier shall notify the purchaser the date and location for the tests giving sufficient
time for the purchaser or his authorized representative to be present. The test procedure
shall be approved by the purchaser.

(N C VALSA)
ASST.PURCHASE OFFICER

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