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BHPV Project
INTRODUCTION
Govt. Polytechnic, Visakhapatnam 1
BHPV Project
INTRODUCTION
Bharat Heavy Plate and Vessels Limited is established in 1969 by
the subsidiary of “BHARAT HEAVY ELECTRICALS LIMITED” by
the government of India in A.P. to fabricate process plant equipment for
the fertilizer, petroleum, chemical, petro-chemical and alloyed
industries.
BHPV`S beginnings were humble; it had a turnover of just 5 lakhs
in 1971 – 72 when commercial production first commenced.
Since then, BHPV has come a long way and exceeded a turnover
of 200 crores expanding its product line to include high technology
equipment and systems like multi layer vessels, turn key cryogenic
plants, storage and distribution systems, industrial boilers, waste heat
recovery systems, oil and gas processing systems etc.
Today, BHPV is the backbone of the Indian’s process industries. Be it
1. Steel or Fertilizer
2. Chemicals or Refineries
3. Petrochemicals or Oil
4. Gas processing systems
5. Nuclear/ Defense /Space
BHPV place a leading role, with a range of products comparable
to the best in the world, manufacture to its own designing or to the
specific designing of the customer consultants.
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BHPV Project
The BHPV product line is exhaustive it encompasses processes
plant equipment, cryogenic equipment and industrial boilers.
This range of equipment is manufactured in collaboration with
some of the world’s leading process equipment manufactures.
BHPV`S COLLABORATORS:
Skoda export, Czechoslovakia, for the installation of equipment
and training of personnel. L`Air Liquide
France, for cryogenic storage systems and air and gas separation
plants, Tonnage oxygen plants up to 2200 TPD capacity, nitrogen wash
plants and purge gas recovery units.
Unitech of USA, for multiple effect evaporation plants. Bignier-
schmid-laurent of France for the manufacture of large-sized cryogenic
storage tanks.
Deals of France for the manufacture of boiler feed water De-
aerators. Bharat Heavy Electricals Limited, India, for the manufacture of
industrial boilers.
ABB Lummus heat transfer, Netherlands for high pressure
(including breech lock) heat exchangers, air cool exchangers, turbine
exhaust condensers, dry cooling towers and fired heaters Hahn & clay in
the heavy industries, U.S.A. for layered high-pressure vessels. BS & B
Engineering Co., Inc., U.S.A. for oil and gas processing systems.
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BHPV Project
COLLABORATION AND ABSORPTION OF TECHNOLOGIES:
Some of the significant collaborations B.H.P.V. entered include:
M/s BSL, France in respect of Field erected Cryogenic Storage Tanks
M/s Delas, France in respect of Deaerators.
M/s ABB Lummus, Netherlands for Heat Transfer Systems.
M/s Hahn & Clay, USA for Advanced Multilayer Technology.
Case- to-case tie-ups, B.H.P.V. entered into include:
Evaporators from M/s Ecodyne Corporation, USA.
Paper & Pulp Digesters from M/s Kamyr AB, Sweden.
Gas Collection Modules from M/s KTI Corporation, USA.
Large Space Simulation Chamber from M/s HVEC, USA.
Primary Reformer from M/s Halder Topsoe, Denmark.
Waste Heat Boiler from Borsig, Germany.
Feed Water Heater from Delas, France.
Argon Recovery Unit from M/s L’Air Liquide, France etc.
Hydrocracker Reactors from M/s Neo-PIGNANI, Italy.
Vacuum Ejector Systems from M/s Korting Hanover, Germany.
LPG Handling & Storage System from M/s Noell-LGA,
Germany.
Ammonia Storage System from M/s KTI, Germany etc. By
absorbing know-how from various world-renowned collaborators,
B.H.P.V. upgraded its status from a mere fabricator of process
equipment to that of an Engineering Company of International
repute.
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BHPV Project
CLIENTS OF BHPV:
The term process industry covers fertilizer, steel, oil exploration
and refinery, chemical and petro-chemical industry. By systematically
building up its capabilities, is today catering to the entire need of the
steel plant industry. Naturally, its client list reads like a who’s who of
Indian industry.
Almost all fertilizer plants in the country including giant units of
the fertilizer corporation of India, National Fertilizers Limited,
Hindustan Fertilizers and chemicals, Rashtriya Chemicals and
Fertilizers Ltd., Indo-Gulf Chemicals and Fertilizers Ltd. Gujarat State
Fertilizers Corporation Ltd., Indian Formers Fertilizers co-operative
Ltd., Bindal Agro Chemicals Ltd., Tata Chemicals and Fertilizers Ltd.,
have repeatedly sought BHPV equipment.
BHPV has been among the foremost suppliers of process
equipment for oil refineries. Mammoth organizations like Indian Oil
Corporation, Hindustan Petroleum Corporation, Bharat Petroleum
Corporation, Madras Refinery Ltd., Cochin Refinery Ltd., have all
placed orders with BHPV for a wide range of equipment.
For the petro-chemical and chemical industries BHPV’s
contribution has been just as striking. BHPV counts Indian Petro-
chemicals Corporation Ltd., Bangaigaon Refinery and Petro-chemicals
Ltd., Maharashtra Gas Cracker Complex, Tamilnadu petro products
Ltd., Indian Drugs and Pharmaceuticals Ltd., Hindustan Antibiotics-all
leaders in their field- as its regular customers.
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BHPV Project
BHPV`s contribution extends to many industries such as
1. Oil Industry
2. Steel Industry
3. Aluminum Industry
4. Paper Industries too.
Industry leaders like the oil and natural gas commission, the Steel
Authority of India Ltd., Rashtriya Ispat Nigam, Bharat Aluminum
Company, National Aluminum Company, and Hindustan Paper
Corporation. BHPV`s esteemed client includes national dairy
development board, Bharat Heavy Electrical Ltd., National Thermal
Power Corporation, besides various heavy water projects and Nuclear
Power Corporation. In short, BHPV has earned a massive vote of
confidence from the entire spectrum of process plant.
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BHPV Project
BHPV – AN OVERVIEW:
Primary Objective: To manufacture customer built capital equipment
for the process industries such as fertilizers, petro-chemicals, petroleum
refineries, chemicals etc.
Incorporation of the Company : 1966
Technical Collaboration : M/s SKODA EXPORT, Provided by
Czechoslovakia.
Commencement of Construction : 1968
Completion of Construction : 1971
Commencement of Production : 1971
Initial Project Cost : Rs. 17.5 crores
Initial Product Mix : Heat Exchanges, Columns, and
Pressure Vessels, Technological,
Structures, piping
Installed Capacity : 23,210 M.T.
Turnover for the year 1996-97 : RS. 300 crore
RESOURCES:
Financial (As on 31st July, 2000)
Authorized Capital (Rs Crores) : 35.00 Crores
Paid up Capital (Rs Crores) : 29.30 Crores
Gross Block (Rs Crores) : 73.36 Crores (Provisional)
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BHPV Project
PRODUCTION FACILITY:
Factory Area : 197 Acres
Total Covered Area : 90,000 Sq. Meters covered area of
Production
Production Shops : 56,000 Sq. Meters
Power Requirement : 3,000 KW from APSEB
No: of Ancillary Units : 11
PRODUCTS MANUFACTURED BY BHPV:
BHPV manufactures various types of Pressure Vessels and
Columns, Air Fin Coolers, Storage Spheres, Transportation Tanks and
Deaerators, Heaters, Paper and Pulp, Heat Exchangers etc., for a host of
applications.
1. PRESSUE VESSELS AND COLUMNS:
From multi-layer construction with design pressure of 280
kg/sq.cm to simple low and medium pressure columns are
manufactured. Tall and heavy columns with lengths up to 90 meters and
weights up to 450 tons. Pressure ranges from vacuum to 55 kg/cm2.
With the back up of experience engineers and a host of heavy capacity
cranes and other equipment, BHPV undertakes site fabrication and
electron on heavy equipment of any size and weight. Pressure vessel
range includes agitator vessels, jacketed vessels & autoclaves limpet
coils.
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2. AIR FIN COOLERS:
Air fin coolers of forced draft type for refineries, petro chemicals,
and fertilizers. Complete units with fans, driving systems, structural
scheme, louvers and paneling.
3. STORAGE SPHERES:
Storage spheres of any size and thickness including low
temperature service. BHPV also undertakes erection and site stress
relieving of these spheres.
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BHPV Project
4. TRANSPORTATION TANKS:
Transportation tanks of stainless steel and carbon steel,
rail or truck mounted including low temperature applications are
manufactured here
5. DEAERATORS AND FEED WATER HEATERS:
BHPV manufactures complete feed water heater systems
including Deaerators, high-pressure heaters and low-pressure heaters.
6. PAPER & PULP:
Batch in continuous pulp digesters & multiple effect
evaporation plant. Today BHPV, with its vast manufacturing capability,
can manufacture process equipment of almost any size. In addition, it
has the requisite handling facilities and being located at Visakhapatnam
has excellent facilities for transporting all size vessels. In case of extra
large equipment that cannot be transported, BHPV undertakes site
fabrication & erection.
7. HEAT EXCHANGERS:
Heat exchangers from low pressures atmospheric lined collars to
high pressure heat exchangers with test pressure as high as 450 kg/cm2,
almost all types of tubular exchangers for practically every requirement
in chemical, fertilizers, petro-chemicals, refinery and heavy water plants
have been fabricated and supplied.
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BHPV Quality:
BHPV reputed for quality and workmen ship of its products.
BHPV quality control department consists of 4 wings.
Quality Assurance
Quality control
Physical testing and Metallographic
Non destructive testing
BHPV has received a number of international recognitions.
BHPV is reputed for quality and workmanship of its product.
BHPV has received a number of international accreditations.
Such as:
ASME U & U2 STAMPS ON
Pressure Vessels
ASME ‘S’ Stamp for Industrial Boilers
STAMI CARBON Urea Reactors
HALDOR TOPSOE Ammonia Reactor, High Pressure Heat
Exchangers
ARABIAN AMERICAN Process Plant
OIL COMPANY
As a part of Total Quality Management Program, B.H.P.V. has
acquired ISO 9001 certification during the year 1993-94 particularly to
boost up its exports and to be competitive in the international market.
Re-certification of ISO 9001 has been obtained in 1996 & 1999.
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BHPV Project
STRENGTH AND WEAKNESS:
STERENGTHS:
1. Highly skilled and dedicated work force.
2. Good industrial relations.
3. BHPV reputed for quality.
Recognisations: ASME U, U2, S and R Lloyds class-I certification
4. Well equipped shops.
5. Strong erection and commissioning set up with cranes etc.
6. Good R&D set up.
7. Large design group.
8. Unit is nearer to a major sea port.
WEAKNESSES:
1. Inadequate engineering capability.
2. Lack of systems engineering capability.
3. Project management.
4. Some worn out and out dated facilities need replacement.
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PROJECTS OF NATURAL IMPORTANCE UNDER EXECUTION
BHPV is reputed for quality and workmanship of its product.
BHPV has received a number of international accreditations.
Such as:
S. No.
Customer Project/EquipmentValue (Rs
crores)
1. BPCL, MumbaiAtmospheric Column & Vacuum Column
34.80
2 BPCL, MumbaiLAS/SS/Duplex NF Heat Exchangers
22.71
3. HFCL, NamrupFirst Distiller, Separator, Holders
1.95
4. ONGC, MumbaiReplacement of Air Cooled Exchangers of process gas Compressors at BHS Plat Form
4.79
5. CPCL, Chennai Supply of Nitrogen plant 10.10
6.SAC, Ahmadabad
5.5M dia. Thermal Vacuum System
32.15
7. IOCL, New Delhi SRU, ARU, SWS 77.05
8. IOCL, New Delhi HPN, SWS, SRU, HGU 1.86
9 BPCL, Mumbai Atmospheric & Vacuum Heater 1.18
10. CPCL, Chennai 130 TPH Boiler Package 2.27
11. FACT, Cochin Thermal Oil Heater 2.20
12. HPCL, VizagRevamping of 50 TPH Oil / Gas Fired Boilers
5.09
13.IGCAR, Kalpakam
Sodium Heater Tank & Its Accessories
0.58
14. NPCIL, MumbaiSupply of steam Condensing Equipment – 2 nos. etc.
108.00
15.Indo–Gulf Corp. Ltd.
Reformer Gas Waste Heat Boiler.
5.12
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BHPV Project
CUSTOMER & COMPETITOR PROFILE
MAJOR CUSTOMERS:
Fertilizer Industries
Petroleum Refineries
Petrochemical Complexes
Steel Plants
Chemical Industries
Power Sector
Nuclear, Defence & Space
MAJOR COMPETITORS:
- I.O.L
- INOX
- L & T
- Linda, Germany
- B.O.C, UK for Cryogenics & Systems.
- Air Products, USA & UK
- KOBE, Japan
- Nippon Sanso, Japan
- HOPM, China
- PRAXAIR, USA
- Larsen & turbo
- GR Engg For Process Plants
- Lloyd Steel
- BHEL
- BABCOCK THERMAX For Industrial Boilers.
- ACC Babcock Ltd
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BHPV Project
RESEARCH & DEVELOPMENT:
Research & Development department was established in 1975 and
is well equipped with high tech equipment to cater to Applied Research
and Product Development. R&D has developed 136 Projects so far.
Some of the products commercialized include:
Titanium Anodes
Titanium Air Bottles
Cryo Vats
Individual Quick Freezing Unit
Super Insulated Piping
Cryo Storage Tank
D.M. Water Plants
BHPV has undertaken Development of Heat Exchangers for Light
Combat Aircraft (LCA) Phase-II has been received from
Aeronautical Development Agency, Bangalore.
SOME AWARDS RECEIVED FOR EXCELLENCE IN R&D
INCLUDE:
-CIS Award for R&D achievement in 1992-93.
The “Chelikani Atchuta Rao Memorial Award” from FAPCCI
for individual achievement in R&D effort in 1996 to Mr.B.S.V.Prasad
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BHPV Project
PRESENT STRENGTHS:
Excellent Design & Engineering Capabilities Manufacturing
facility.
The State-of-the-art manufacturing facilities.
Accomplished image as a supplier of Quality Products in the
Domestic and International markets.
High degree of customer confidence
Technological tie-up arrangements
Well-trained and qualified work force and Engineers.
Sound work culture & harmonious Industrial Relations.
Extensive computerization and Projects Management Skill
Capability to supply Projects & Systems on turnkey basis.
PLANS & STRATEGIES:
To grow as an Engineering, Procurement and Construction
Company and on LSTK Contracts
To enlarge Export Business
To focus on Human Resources Development
To resort to extensive computerization And Automation for
reduction of cycle time.
Improvement of quality
Reducing costs.
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BHPV Project
To forge strategic business alliances with International
Companies to derive technological advantages and Marketing
advantages.
To strive for continuous updating of technologies to be on par
With International Companies.
To change the work culture to be compatible with current Market
demands.
INTRODUCTION OF THE PRODUCT:
Steam Generators are vital package units for almost every
industry for either steam for process or power. B.H.P.V a premier
organization for manufacture of process equipments such as pressure
vessels, heat exchangers and columns has entered into the field of steam
generation as a part of diversification in the year 1981. Prior to entering
the steam generation field B.H.P.V. has successfully manufactured and
supplied to BHEL some of the vital equipments such as drums, water
walls, power piping etc.,
B.H.P.V. CAPABILITIES:
Thermal
Product design.
Instrumentation
Fuel systems
Structural Design
Manufacturing technology
Quality Assurance
Control Procedures.
Erection
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BHPV Project
The manufacturing technology and various other standards
adopted by CE have been fully implemented in BHPV and proved its
capability as one of the leading boiler manufacturer.
EQUIPMENT FABRICATION TO SYSTEMS SUPPLY:
Systems Packages:
BHPV has acquired on one hand a vast experience in
design, manufacture, supply, installation of process equipment and has
developed an expertise in handling large turnkey systems in the areas of
cryogenic & combustion systems.
Systems Engineering:
BHPV has developed over the years a strong system
design group adequately manned by qualified and experienced engineers
both in process and mechanical design. System design group has
capability of designing various systems for the oil and gas sector,
Metallurgical industries, paper and pulp etc. BHPV has already supplied
a number of systems to ONGC, IOCL, HPCL and other oil sector
industries as well as other industries such as NALCO, Hindustan paper
corporation etc.
These include:
1. Skid mountaineer test separators
2. Gas dehydration, Packages Filter separators,
3. Desalters and Heater Treaters
4. Gas collection modules
5. Evaporation plants Vacuum ejector systems etc.,
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BHPV Project
SYSTEM RANGE:
The systems that BHPV offers to oil and gas sectors are:
1. Separators:
Horizontal 2 & 3 phase
Vertical 2 & 3 phase
Defoaming 2 & 3 phase
Micro scrubbers
Oil Skimmers
2. Heaters:
Horizontal Direct Fired (HSFH)
Liquid Bath Indirect (WBIH)
Salt Bath (SBH)
Propane Vaporizers (IHPV)
Steam generators
Low pressure (SG)
3. Oil Treaters:
Vertical Heater Treaters
Horizontal Heater Treaters (HDT)
Electro static Heater Treaters (HET)
Electro static Desalters (HED)
4. Low Temperature Separators(Joule-Thompson
(JT)):
Heated Bottom
Hydrate Inhibited
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BHPV Project
5. Glycol Dehydrators:
Contactors
Regenerators
Direct Fired
6. Oil and Gas Manifolds and Gathering Stations
7. Dry Desiccant Adsorption (DDH)
8. Desulphurization of Gas and Liquid:
Amine
Hot Potassium Carbonate
Direct Oxidation
9. Sulphr Recovery:
Claus
10. Gas Liquids Recovery Plant:
Hydrocarbon Stabilizers
Fractionators
Expander
Refrigerated
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BHPV Project
PRESSURE VESELS
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PRESSURE VESELS
Pressure vessel is a closed container containing fluid under
pressure (internal or external) more than the atmospheric pressure used
for channeling and storing fluids and for performing various unit
operations.
Mounded storage vessel comprises the storage of pressurized
gases at ambient temperatures in horizontal cylindrical vessels placed
near ground level and covered with suitable backfill. Several vessels
may be located side by side in one mound. The decision for the earth
covered type of installation is mainly justified by the safety advantages
in respect to external influence on the vessel; such has high temperature
in case of fire and dynamic pressure from near by explosion.
The design procedure of the mounded storage vessel conforms to
ASME-Boiler and Pressure vessel code, section VIII pressure vessels –
Division II . The various stresses (due to pressure, seismic, mound and
dead loads) on mounded storage vessel are calculated. Stress analysis of
mounded storage vessel is done with the help of the FEA (Finite
element analysis) package ANSYS. Induced stresses obtained from
manual calculations using fundamental formulae and induced stresses
obtained from FEA using ANSYS were compared.
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BHPV Project
1.2 HISTORY OF PRESURRE VESSELS:
Pressure vessels are a group of critical equipments of different
types of construction used in modern industries for various operations
like storage, process etc. of various fluids. These equipments can be
Atmospheric Storage Tanks
Pressurized Tanks
Process columns and Vertical Pressure Vessels
Horizontal Pressure Vessels
Heat Exchangers
Process Heaters
Boilers
Through out the world the use of process equipment has expanded
considerably. In petroleum industry, pressure vessels are used at all
stages of processing oil. At the beginning of cycle, they are used to store
crude oil. Much different types of these pressure vessels, process the
crude oil into oil and gasoline for the customer. The use of pressure
vessels in chemical industries is equally extensive.
Pressure vessels are made in all sizes and shapes. The smaller one
may be no longer than a fraction of an inch in diameter; where as large
pressure vessels may be of dia 150ft. or more in India .Some are buried
in ground or deep in oceans, most are positioned on ground or supported
on platform and some are found as storage tanks and hydraulic units in
aircrafts .The internal pressure to which process equipment is designed
is varied as size and shape.
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BHPV Project
The usual range of pressure for monoblock construction is about
15 psi to 5000 psi. Although there are many vessels designed for
pressure below and above that range .The ASME boiler and pressure
vessel code section VIII Div.II, specifies a range of internal pressure
from 15 psi at bottom to no upper limit. However at an internal pressure
above 3000 psi with ASME code section VIII Div.I, special design
consideration may be necessary.
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BHPV Project
MOUNDED STORAGE VESSEL:
For the storage of combustible liquids under atmospheric pressure
and liquefied gases under high pressure, the horizontal cylindrical steel
vessel with earth cover has been applied with in last years. Mounded
storage is applied because it provides additional safety compared to
above ground storage of gases in spheres or bullets. Its major advantage
is that a BLEVE (boiling liquid expanding vapour explosion).
Other benefits of the mound are
Protection of the vessels against:
o Heat radiation from near by fire
o Pressure wave originating from an explosion
o Impact by flying objects
o Sabotage etc.
It satisfies environmental and aesthetic requirements,
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BHPV Project
It results in reduced site area due to less strigent inter spacing
requirements
The safety distance to the site boundary can be reduced
considerably.
The design lifetime of mounded storage vessel is 25 years.
Depending upon site conditions, ground water level and operational
requirements, the vessels may be installed either at ground level or
excavation, after which they shall be backfilled. Since the vessels shall
be installed above ground as an earth mound, hence the term “mounded
storage”. Vessels in open under ground vaults and excavations are not
considered to be mounded storage vessels.
The vessels are provided with connections (e.g. manholes,
pressure relief valves and instrument connections) protruding through
the top of the mound. Only if dictated by operational requirements may
a bottom discharge in an inspectional tunnel be considered.
The vessels shall be completely covered; only the top connections
(manholes and /or dome) may protrude through the mound. If more than
one vessel is placed in a single mound then the minimum distance
between the vessels depends on the construction activities like welding,
coating, back filling and compaction of the backfill material. A distance
of 1 m is considered to be a minimum requirement.
The maximum diameter is usually determined by factors such as
design pressure, fabrication, post weld heat treatment requirements,
transport limitations, subsoil conditions and economy of design (8
meters may be regarded as a practical upper limit).
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BHPV Project
For vessels, which are founded on a sand bed, the length of the
vessel should be no more than 5 times the diameter, in order to prevent
the design shell thickness being governed by longitudinal bending of the
vessel due to possible differential settlements or constructional
tolerances of vessels and foundations.
The maximum allowable length is usually determined by the
subsoil conditions (especially if differential settlements re expected),
size of available site and economy of the design.
The above restrictions limit the maximum gross volume of a
vessel to approximately 3500 m3. There is no limitation to the minimum
size of the vessel, except for practical considerations.
COMPONENTS AND THEIR DESCRIPTION -:
1. SHELL-:
These are the cylindrical sections to contain the process fluids and
to withstand pressure and temperature of process fluids. These sections
are also to support the internal and external attachments.
2. END COVERS -:
A) Dished ends -:
Dished ends are the formed heads or closers used in the
fabrication of pressure vessels. These are the heads for closing the
cylindrical shells. The principal advantage of the dished heads is the
large reduction in the discontinuing in shape at the junction between the
cylindrical vessels and the closures, resulting in a reduction of
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discontinuity stress at or near the junction. Examples of dished ends are
torispherical, elliptical, hemi-spherical, flat dished ends etc.
i) Torispherical dished end-:
Decreasing the local stresses, which occur in the inside corners of
the head, can increase the pressure rating of torispherical dished ends.
This may be accomplished by forming the head so that the inside corner
radius is made at least equal to three times the metal thickness for code
construction. The knuckle radius should in no case shall be less than 6%
of the inside diameter, also the radius of dish may be made equal to or
less than the diameter of the head. These heads are fabricated on the
basis of using the using the outside diameter as the nominal diameter.
ii) Elliptical dished heads-:
The elliptical dished heads are formed on dies in which the
diametrical cross section is an ellipse. If the ratio of major to minor axis
is 2:1 the strength of the head is approximately equal to the strength of
the cylindrical shell having the corresponding inside and outside
diameter.
iii) Hemispherical heads -:
For a given thickness, hemispherical heads are the strongest of the
formed heads .These heads can be used to resist approximately twice the
pressure rating of an elliptical dished heads or cylindrical shell of the
same thickness and diameters. The degree of forming and
accompanying costs are greater than for any of the heads previously
described; also the available sizes formed from single plate are more
limited.
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b) Flat ends-:
Flat ends or flat heads are also used for closing the mounded
vessels. But they are limited in the application of pressure vessels. For
the same temperature and pressure, the required thickness of flat heads
is more than he dished ends. These flat heads will be either directly
welded to the shell or connected by bolting connection. These flat heads
are generally used for low pressure vessels.
3. NOZZLES-:
Nozzles are the branch connections, which are welded to the
shell. The pipe lines, which bring the fluid to and from the mounded
storage vessel, will be attached to these branch connections. Also the
nozzles are useful lf connecting o pressure gauge, relief valves, thermo
wells and other such instrument and control equipments.
4. FLANGES-:
Flanges are used for making connections for piping and nozzle
attachments. Flanges may be either forged or made of plate material.
Flanges can be divided into the following standard types for all pressure
ratings
a) Weld neck
b) Slip on
c) Lap joint
d) Screwed and
e) Blind flanges etc.
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BHPV Project
5. STIFFENING RINGS -:
A cylindrical vessel under external pressure has an induced
circumferential compressive stress equal to twice the longitudinal
compressive stress because of external effects alone. Under such
condition the vessel is apt to collapse because of elastic instability. The
collapsing strength of such vessels may be increased by the use of
uniformly spaced internal or external circumferential stiffening rings.
Stiffening rings are the circular rings welded to the vessel externally or
internally.
6. REINFORCEMENT PADS -:
All openings such as nozzles, holes, manholes and hand holes
made in the shell in which the openings is over 50mm diameter should
be reinforced by reinforcement pads .It is a circular plate with a circular
hole .Due to weakening effects on shell and because of openings made
in the shell for nozzles etc, and wherever compensations are required,
normally reinforcement pads are provided by welding another plate
around the hole to add sufficient metal to compensate for the weakening
effect of the opening.
7. MANHOLES-:
Manholes are necessary in closed vessels to permit inspection,
cleaning, repairs etc. Manholes may be located on the shell or on the
roof or at both locations. Manholes on shells have the disadvantage that
they usually cannot be opened unless the vessel is empty and therefore
not used as much as roof manholes for inspection.
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BHPV Project
HEAT EXCHANGERS
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HEAT EXCHANGERSHEAT EXCHANGERS
1. Introduction: Heat Exchangers are essential equipment of any process
plant. These are devices for exchange or transfer of heat from one fluid
to other. Plant operation economics are chiefly controlled by the
effectiveness of the utilization and recovery of heat or cold by suitable
heat transfer equipment.
2. Types of Heat Exchangers: There are No. of heat exchanger types
based on method of heat transfer and constructional features. The
process designer has to select the best suitable type that meets the
performance & operational requirements.
Following is the list of heat transfer equipment:
S.No Type of heat transfer equipment
1. Shell & tube H.E
-Fixed tube sheet exchanger
-U-Tube exchanger
-Floating heat exchanger
2. Single tube exchangers
-Double pipe exchanger
-Trombone cooler
-Coils in vessel
3. Parallel plate exchanger
-Gasketed plate exchanger
-Spiral plate exchanger
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-Lamella exchanger
-Plate evaporator
4. External heating type
-Jacketed vessel
-Steam tracing
5. Heat transfer without surfaces
-Flash evaporators
-Direct contact condensers
-Cooling towers
-Heat transfer of fluids
-Direct heating
-Submerged combustion
6. Extended surfaces
-Air cooled exchanger
-Plate fin exchanger
-Tank heating with finned tubes
-Solids heating with a bank of longitudinally finned tubes
-Air heater
SHELL AND TUBE HEAT EXCHANGERS:
From medium to high-pressure heat exchangers with a test
pressures as high as 450 kg/cm2 and temperature ranging from –650C to
–9000C. Almost all types of tubular exchangers for practically every
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requirement in chemical, fertilizer, petro-chemical, refinery and heavy
water plants have been fabricated and supplied.
BHPV has over 15 years experience in manufacturing a wide
Variety of Heat Exchangers, numbering over 2000, with its own Design,
as well as to third party designs and supplying them to almost all
process plants in the country.
HEAT EXCHANGER ENGINEERING CAPABILITY:
BHPV is the member of Heat Transfer and Fluid flow Services
(HTFS), U.K. and Heat Transfer Research Institute (HTRI), U.S.A.
The designs are based on the most reliable on competitive
specifications, from standard process heat exchangers to high
technology exchangers required in petro-chemical, fertilizer, oil refinery
and other process plants.
Shell and Tube heat exchanger designs cater for process pressures
from vacuum to 600 bars and more than 600 bars for process
temperatures from cryogenic to 13000 C or more than 1300oC in various
materials of construction
Such as
Carbon steel
Low alloyed steel, high alloyed steel
High alloyed steel
Non-ferrous materials
Titanium, Zirconium and other patented materials.
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HEAT EXCHANGER MANUFACTURING CAPABILITY:
It is based on the service conditions, and as dictated by equipment
design, BHPV can manufacture and supply Heat Exchangers as large as:
4-meter shell diameter
450-ton weigh
600-mm thick tube sheets
Shell thickness upto 100 mm-
Monowall: Plate construction Beyond 100 mm
Monowall: Forged construction Beyond 75 mm
Multi layer construction
16 METERS LONG:
BHPV has manufactured and supplied high pressure shell and
Tube Heat Exchangers incorporating the following high pressure seals:
They are:
Delta
Double Cone
Diaphragm
Lens
Lip Seal
Sealing plate package
Gray Lock
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In case of high-pressure seals with large diameter studs at flanged
joints, special studs tensioning devices are provided for uniform
tightening of studs for effective seating of the seal for leak tightness.
BHPV processes special computer programs for analysis of tube bundle
vibration. BHPV utilizes CNC drilling machine for drilling tube sheets
there by maintaining the tolerances required. Programmable tube-to-
tube plate welding facility is available for better productivity and higher
accuracy in BHPV.
BHPV AND LUMMUS HEAT TRANSFER SYSTEMS
(LHTS):
BHPV has entered into collaboration with Lummus Heat Transfer
Systems (LHTS) for transfer of technology in design, manufacture and
supply of shell and tube heat exchangers including
1. High-Pressure Breech Lock Exchangers,
2. Air-Cooled Heat Exchangers,
3. Air Cooled Turbine, Exhaust Condensers,
4. Dry Cooling Systems and
5. Fired Heaters.
LHTS is a wholly owned subsidiary of combustion engineering,
with heat require at The Hague, Netherlands.
LHTS has over 50 year experience, which helps guide BHPV
competently through complex decisions in designing the best and most
competitive heat transfer equipment.
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LHTS is the largest and most qualified engineering company in
this field and continuous to develop new technologies. Under this
collaboration agreement, BHPV can now provide total engineering
service of heat transfer systems hardware and compete against another
internal manufactures.
As a member of HTFS-UK and HTRI-USA, with the proven
manufacturing expertise in heat exchanger and now with the backup of
transfer of latest heat exchanger technology from NHTS, BHPV
emerges with high degree of technical competence to solve any problem
that the client may experience in heat transfer systems. Clients will
receive our guarantee on performance and workmanship.
HEAT EXCHANGERS WITH SPECIAL HIGH
PRESSURES BREECH LOCK CLOSURES:
There is a growing demand for heat exchangers that perform
efficiently under high temperatures and pressures. Leak tightness at
flanged joints to avoid danger of explosion is very critical in the case of
exchangers handling lethal fluids, and this calls for a high performance
sealing mechanism. It is vitally important that the exchangers are
constructed to facilitate disassembly and re-assembly because they
handle corrosive fluids and periodic inspections are necessary.
BHPV offers heat exchangers with the above critical
requirements. Under license from Lummus heat transfer systems,
Netherlands, Breech lock closure type heat exchangers with competitive
design and international quality standards are being maintained in
BHPV Visakhapatnam, India. Breech lock closure type heat exchangers
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offer an excellent sealing performance under high temperature and high-
pressure conditions.
The exchangers for that a unique channel construction and offer the
following advantages:
1. It is possible to re-tighten the internal tube sheet to the shell gasket from
outside during operation.
2. The channel forging via a special threaded ring construction absorbs the
hydro static pressure load on the channel cover not by heavy bolding.
3. The bolts in the channel cover are only sized for gasket compression
loading, This results in relatively small size bolts that can be tightened
using normal wrenches, thus eliminating the lead for hydraulic bolts
tensioning devices required on conventional bolted flanged Exchangers.
The channel cover is relatively thin.
4. The numbers of flanged joints are reduced to a minimum due to the
integral constructions of pressure parts.
5. When the internal surface of the channel is stainless steel weld overlaid,
the risk of overlay disbanding & stress-include cracking is minimized
due to the elimination of internal attachment welds, threaded holes in
the pressure forging and tension force on the weld overlay.
6. The channel cover is not needed to be cladded because of a stainless
steel diaphragm. Assembling is quick and easy and can be carried out
by unskilled labor, because:
i. No breaking or cutting of welded parts required.
ii. No gasket grinding or welding required.
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iii. No bolt tensioning equipment is required; therefore, no
complicated strain gauge measurements are required and are a
large number of tightening cycles necessary.
FIRED HEATERS:
BHPV manufactures large verticals, cylindrical types and box
type heaters for fertilizers, refineries and petro chemical units. BHPV
has entered in to a full-fledged collaboration agreement with M/S.ABB
LUMMUS HEAT TRANSFER of the Netherlands, a fully owned
subsidiary of combustion engineering Inc., USA for design,
manufacture, supply, erection and commissioning of fired heaters.
BHPV is fully geared to take up the following types of fired heaters.
They are:
Startup heaters
Recycle heaters
Charged heaters
Hot oil heaters
Crude and vacuum heaters
Steam super heaters
Coker heaters
Vis-breaker heaters
Catalytic reformer heaters
Reboilers
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After establishment as a renowned supplier of process
equipment’s, Air separation plants and boiler systems, BHPV has
entered into a full-fledged collaboration agreement with M/s. LUMMUS
HEAT TRANSFER SYSTEM (LHTS) of Netherlands, a fully owned
subsidiary of M/s. Combustion Engineering Company USA, for design,
manufacture, erection and commissioning of Fired Heaters.
The heater efficiency can be improved by using Recuperative type
air preheaters connected to existing/newly designed heaters. The designs
are based on proprietary computer programs, so that customers can have
the most reliable and cost competitive fired heaters with this backup
BHPV emerges with a high degree of technical competence to solve any
problem that a client may experience in boiler and fired heaters.
BHPV has already supplied a number of fired heaters,
which are operating successfully to the utmost satisfaction of the
customer. With the experience already gained in the manufacturing,
erection, commissioning of fired heaters. BHPV is now in a position to
take-up the total system and a turnkey bases with the backup of M/s.
LHTS.
BHPV has executed a number of contracts with its excellent
project management systems. BHPV is equipped with most modern
machinery for manufacture of various items required for fired heaters to
achieve the required quality standards commensurate with the functional
requirements.
WASTE HEAT RECOVERY STEAM GENERATORS (WHRSG):
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BHPV supplied 2x70 T/hr. Waste heat recovery steam generators
to Indian petro-Chemical Corporation Ltd., Baroda with design backs up
of Holland construction group (HCG), Netherlands.
The WHRSG are used behind 2x36 MW gas turbines of general
electric, USA enhancing cycle efficiency from a mere 25% with gas
turbines alone to about 40% in conjunction with WHRSG. With the
boom in natural gas production leading to settling up of captive as well
as grid power generation units using gas turbines. BHPV is fully greated
up to supply WHRSG units of various capacities, vital for increase of
fuel efficiency.
BHPV’S SPECIAL PROJECTS:
Large Space Simulation Chamber Project (LSSC):
Physical conditions in our space are substantially different from
these existing in the atmosphere surrounding the earth. Before sending a
satellite in to outer space. It is essential to test all its characteristics
under conditions that approach-as closely as possible-those which the
satellite has to with stand. This is done in Large Space Simulation
Chamber (LSSC).
BHPV has set up a L.S.S.C. at Bangalore for ISRO satellite center
(ISAC). The entire project was done on turnkey basis with technical
backup from high vacuum Equipment Corporation, etc. It is unique in
India very few chambers elsewhere in the world have so many features
in one chamber.
Design methods of various components:
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Which fall under ASME code is covered by other lecturers. The
designs of components that are special to heat exchangers are discussed
here. For a systematic design calculation comprehensive formats are
developed which are appended together with design data sheet prepared
by process designer.
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1. Tube Sheet:
It is the most important part of a heat exchanger. These are flat
plates which will be drilled with a multitude of holes into which tubes
are fixed by expansion or by welding. It provides a rigid support to all
the tubes and keeps the shell & tube side fluid separated. It has to
withstand the pressure, temperature & corrosive nature of both fluids as
well as any surges in operating conditions due to upset or emergency. Its
design cost for utmost caution. TEMA standard gives due consideration
for the stresses developed due to pressure & differential thermal
expansion because of tube & shell side temperature. In fixed tube sheet
heat exchanger the stresses developed in tubes, shell & tube plate are
calculated to ensure that allowable stresses are not exceeded. TEMA
standard gives rules for determining tube sheet thickness when subjected
to thermal gradient. The thermal stresses due to differential thermal
expansion is expressed as an equivalent differential expansion pressure
Which takes into account the flexibility of the tube sheet, shell & tubes.
The equivalent differential expansion pressure is combined with the
operating pressure to arrive at the tube sheet thickness. A means of
reducing the thermal stresses in fixed tube sheet heat exchanger is the
inter position of a fairly flexible element called expansion bellow in the
comparatively stiff shell. The expansion bellow permit under strained
expansion/contraction of shell. A comprehensive format for design of
fixed tube sheet is developed & appended formals for other type of tube
sheets are also appended. It may be noted that ASME code is gradually
introducing the design rules of tube sheets.
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2. Tube to Tube Sheet Joint:
The connection of the tubes of tube sheets is the most critical
element of element of a shell & tube exchangers because its reliability
depends upon the integrity of the many parallel tube to tube sheet joints.
Consequently each of the many joints must be virtually free of defects.
Tube to tube sheet joints are subjected to heavy shear stresses during
testing and operation arising out of the weight of tube bundle &
contained fluid thermal loading due to differential expansion of shell &
tubes and between tube to tube situated in different zeros of tube bundle.
The tube joints are also subjected to disorganizing forces due to
impingement of high velocity fluids on the tubes, vibration of tubes &
exchanger etc., the joints are also exposed to chemical corrosion, stress
corrosion & crevice corrosion. The tube joint must be able to with stand
all the above static, dynamic thermal stresses during all operating
conditions. It should ensure a strong and stable leak proof joint to isolate
the working fluids from one another absolutely.
3. Baffles & Support plates:
These plates serve as baffles to deflect to shell side fluid over
tubes and also as tube supports to maintain correct tube pitch and
prevent flow induced vibrations.
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MACHINERY
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Shearing Machine:
It is mainly used for to remove the excess or required part of
sheets or plates by means of shearing.
Available machinery capacities:- Maximum width is - 3150mm
Maximum thickness – 20mm
General limitations of shearing machine:
The edges of C.S and S.S shell plates of heat exchangers are to be
compulsory be machined by edge planning machine after shearing
operation irrespective of the thickness.
Rolling Machine:
Scope: Plates up to 50mm thickness maximum may be rolled. The
maximum width of plates that may be accommodated is 3000mm.
Incase of other rollers, individual capacities may be referred from the
technical specifications. Hot rolling is restricted due to machine
difficulties.
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Maximum Rolling Capacity is 60 mm in cold condition and 170 mm in
hot condition.
Stress relieving:
After complete the job some stresses induced in job. These
stresses induced due to various operations like rolling, bending, pressing
etc, This stress removing by heat treatment. Stress relieving process
mainly in furnaces.
BHPV has the largest heat treatment furnace in India, the size
being 5.5 meters width, 5.5 meters height and 36.5 meters long.
One more furnace of 200 Tones capacity and 15mts. Bogie length
has been added.
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CRANES:
The maximum crane lifting capacity is 120 tones, but loads up to
250 tones can be lifted with improvisation. Maximum Rolling Capacity
is 60 mm in cold condition and 170 mm in hot condition.
Plate edge planning Machine:
Plate edge planning machine is mainly used for to bevel or plane
the surface of the plate.
1. Maximum length of the Plate up to – 12000mm
2. Maximum thickness - 800mm
VERTICAL TURNING AND BORING MACHINE:
It is mainly consisting of rotating circular table used for turn &
bore the large type of circular parts & Dished ends, provide bevel to the
edges of circular parts.
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A number of Vertical and Horizontal Boring Machines with a
Maximum capacity of 5 Meters diameter and 200 MM Spindle dia.
Various types of Vertical turning & Boring machines are available in
BHPV.
VTB machines & its capacities
Light machine shop (LMS):
Small Vertical turning & Boring machine – Ø 850/900mm Height - 1No.
Small Vertical turning & Boring machine - Ø 1050/1100mm Ht. -1No.
Small Vertical turning & Boring machine - Ø 1250/1100mm Ht - 4Nos.
Heavy machine shop (HMS):
Medium VTB machine - Ø2500/5000Ht. – 2NOs.
Large VTB machine - Ø4000/5000Ht - 2Nos.
Large VTB machine - Ø5000/5000Ht - 2Nos.
HORIZONTAL BORING MACHINE:
It is consist of horizontal spindle mainly used for bore the pipes,
bevel the ends of the pipes, machining the flat surfaces.
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LIGHT MACHINE SHOP:
Small horizontal boring machine - Ø80mm - 2 no.
Medium horizontal boring machine - Ø125mm - 1 no.
Horizontal Boring machine - 200mm - Ø200 - 1 No.
Horizontal Boring machine - 160mm - Ø160 - 1 No.
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HYDRAULIC PRESS:
Function: It is mainly used for provide various shapes to plates like
conical, Dished, Tory conical etc,.
Mechanism: It is completely hydraulic control system. Very large forces
can be created in this system. Heavy load applied by hydraulic pressure
pump is provide flow energy to the oil. Pump adds pressure to the oil.
A hydraulic system is generally concerned moving of press male
part. Female part is fixed one.
Capacity of Press:
Deep Drawing Hydraulic Press of 1600 T capacity and a number
of Welding Rotators of capacity up to 250 tones.
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WELDING MACHINERY:
Welding equipment such as Manual Arc, Sub merged Arc, TIG,
MIG, Plasma including the latest high productive welding equipment
such as Twin Head submerged arc welding, Narrow Gap submerged arc
Welding and Bi-cathode TIG welding, Tube Finning Machine
Submerged Arc welding Machine:
CNC DRILLING MACHINE:
Single Spindle CNC Deep hole Drilling Machine with Gun
Drilling attachment and 2 Nos. CNC drilling machines, which can
employ conventional drills. Another CNC Deep hole drilling machine
has been installed recently by HMT.
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It is mainly used for to provide tube sheet holes. It is
completely computerized drilling machine. Drilling is done in three
processes.
1. Pre drilling
2. Drilling &
3. Reaming or finishing.
Above three operations are performed in single operation. Initially
the programmed is feed in the computer. With that program machine is
operated. It is very accurate and faster.
Capacities:
Component material: carbon steel, Stainless steel, Clad material.
Dimensions: Maximum diameter is-3000mm,
Thickness-600mm
Drilling capacity: 40mm dia maximum is steel
No of spindles – 2
Spindle pitch – 200 to 300mm
Spindle speed: 150 to 3000rpm.
Position tolerance: ±0.025mm over 1000mm.
Repeatability: ± 0.0125mm.
Drift on drill holes: 0.05mm in 100mm, 0.15mm in 400mm,
0.20mm in 600mm.
Overall dimensions of the machine: 19.5m X 10.5m X 7.1m.
Total connected power: 120KW.
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Total weight of the machine: 90Tonnes.
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MATERIALS
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PHYSICAL PROPERTIES
1. Ultimate tensile strength
2. Yield strength
3. Elongation
4. Strength at elevated temp.
5. Hardness
6. Impact strength
7. Creep
8. Fatigue strength
9. Ductility
10.Malleability
11.Co-efficient of thermal expansion
12.Thermal conductivity
13.Electrical resistivity
CHEMICAL PROPERTIES
1. Chemical composition
2. Addition of main alloys like Cr, Ni, etc.
3. Addition of micro alloys like Va, Ta, etc.
4. Carbon Equivalent, C.E.
C.E = C + Mn + Cr + Mo + V + Cu + Ni
CLASSIFICATION OF MATERIALS
Materials are broadly classified as
1. Carbon Steels
2. Low Alloy Steels
3. Stainless Steels
4. Clad Steels
5. Special Steels ( Properties enhanced by H.T )
a. Non – ferrous Materials
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CARBON STEELS
1. Alloy of carbon and iron
2. Largest Group and commonly used
3. Cheaper
4. Easy to fabricate
5. Ductile
6. Good Weld ability
7. Low corrosive service
8. Low or intermediate strength ( UTS = 40 to 60 kg/mm2)
9. Suitable for elevated temperature up to 400° C
10. Suitable for low temperature up to minus 60° C
11. UTS falls at high temperature
12. Some ASME Materials :
Plate - SA 516 Gr.60/70, SA 537 Cl.1, SA 285 Gr.C
Pipe - SA 106 Gr.B, SA 333 Gr. 1/6
Forging - SA 350 Gr. LF2, SA 105
LOW ALLOY STEELS
1. Alloy elements up to 9%
2. Alloying elements : Cr, Mo, Ni
3. Alloys increase strength
4. Cr, Mo improves resistance to scaling, oxidation and
graphitization at high temperature
5. Cr-Mo steels resist , sulfidation, hydrogen attack
6. Higher creep / rupture strength than C.S
7. Suitable up to 650ºC
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8. Ni - alloy steel possess good notch – toughness properties and
suitable for low temp.
9. up to minus 196ºC
10. Greater care is needed during fabrication and welding
11. Some ASME Materials :
Plate - SA 387 Gr.11/12/22 (Cr - Mo alloy)
SA 204 Gr.A/B/C, SA 302 (C-Mo alloy)
SA 203, SA 353 (Ni - alloy)
Pipe - SA 335 P1/P11
Forgings - SA 182 Gr. F11/F12
SA 336 Gr. F11/F22
Pipe fittings - SA 420 WP 11 /WP 12
STAINLESS STEEL:
1. Cr. Content more than 11 % but less than 30 %
2. Excellent resistance to corrosion
3. Good impact strength at low temp.
4. Strength and oxidizing resistance at elevated temp.
AUSTENITIC STAINLESS STEEL:
1. Alloy of Cr - Ni - Fe
2. Largest group (SS 304, SS 316, SS 321, SS 347, SS 309)
3. Good strength
4. Ductile
5. High corrosion resistant
6. High impact strength at low temp.
7. Non – Magnetic
8. Strength and hardness increase by cold working
9. Some ASME Materials:
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Plate - SA 240 Type 304 / 316 / 321 / 347
Pipe - SA 312 TP 304 / 316 / 321 / 347
Forging - SA 182 Gr. F304 / F316 / F321 / F347
FERRITIC STAINLESS STEEL:
1. Cr. Content : 16 - 30 %
2. Wear resistant
3. Oxidation resistant
4. Low ductility at low temp.
5. Suitable for less corrosive environment
6. Used for cladding / lining, column internals like trays
7. Cheaper compared to austenitic S.S
8. Magnetic
9. ASME Material : SA 240 TP 430
MARTENSITIC STAINLESS STEELS:
1. Cr. Content - 11- 16%
2. Hard enable by heat treatment
3. Magnetic
4. Least corrosive resistant of S. S grade
5. ASME Material : SA 240 TP 410
a. CLAD STEEL
6. Base : C.S or LAS
a. Clad : Corrosive resistant lining( S.S, monel etc)
7. Low cost
8. Methods of cladding : Hot rolling, explosion cladding
9. Bonding strength greater than 20 000 psi in shear
10. Hot or cold formed.
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11. Light loaded internal supports can be attached to clad
surface.
12. Some ASME Material :
SA 516 Gr.60/70 + S.S 304 Clad
SA 387 Gr.11 Cl.2 + S.S 410S Clad
SA 516 Gr.60/70 + SB 127 Clad
SPECIAL STEELS:
1. Mechanical properties enhanced by heat treatment by
quenching and tempering
2. Higher strength
3. Used for high pressure application
4. Used where weight reduction is essential
5. Very difficult to fabricate. More care needed in fabrication
& welding
6. Some are C.S materials; but most of the materials are LAS.
7. Some ASME Materials :
SA 517 Gr. A to P, SA 724 Gr.A
CAST IRON:
1. Alloy of C,Si ,Fe
2. Ductility is low
3. Can be cast to complicated shapes
4. Can take compressive loads.
5. Not permitted in pressure vessel applications.
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NON-FERROUS MATERIALS
Non – ferrous metals / alloys are used wherever following properties are
required, notwithstanding their higher cost.
1. Higher Corrosive Resistant to most of the process liquids.
2. Ability to withstand very high temperature.
3. Increased life of equipment.
4. Good thermal conductivity.
5. Improved mechanical strength.
6. High melting point.
7. Low density.
8. Some materials.
MONEL (Ni - Cu) - SB 127, 164, 165
INCONEL (Ni - Cr - Fe) - SB 163, 166, 167
ALUMINIUM
TITANIUM - SB 265, 337
CUPRO-NICKEL (Cu - Ni) - SB 151, 171
SERVICE REQUIREMENTS:
1. Ambient service
2. High temperature service
3. Low temperature service
4. Corrosive service
5. Hydrogen Induced Cracking
6. Sour service
AMBIENT SERVICE:
1. Operating conditions are at ambient conditions.
2. C.S materials are commonly used
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REQUIRED MATERIAL PROPERTIES:
1. Tensile strength at elevated temp.
2. Creep/ rupture strength at elevated temp.
3. Resistance to scaling.
4. Resistance to corrosion.
5. Coarse grained material
MATERIALS:
1. LAS are best suited for elevated temp. They have good
scaling resistance and strength.
2. S.S can also be used for elevated temp.
3. Carbon steels are not suitable for elevated temp. Above
400°C, carbon steels, materials have low creep resistance,
decarburize faster, graphitize, excessive scaling.
APPLICATIONS:
1. Reactors in petrochemical, petroleum, fertilizers industries.
2. power generation equipments
LOW TEMPERATURE SERVICE:
In low temperature service, equipments operating at temp, below 0°C
REQUIRED MATERIAL PROPERTIES:
1. Notch toughness at low temp .i.e. ability to deform plastically at
stress
concentration to resist brittle fracture at notches.
MATERIALS:
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1. C.S materials are suitable up to minus 60°C.
2. LAS materials like Ni-alloys are suitable up to (-) 196°C.
3. S.S is ideally suitable up to (-) 255°C.
APPLICATIONS
1. Liquid oxygen/liquid nitrogen storage facility.
2. Cryogenic applications
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WELDING
TECHNOLOGY
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WELDING JOINT DESIGN AND WELDING
SYMBOLS
INTRODUCTION
Mechanical components, vessels or any structures are manufactured by
assembly / joints of two or more parts due to the following reasons.
Limitation on maximum size of raw material
Complexity of shape
Combination of raw materials
Limitation on size of component parts for transportation
Ease of replacement in service.
Joints can be made mechanically using bolts, rivets, keys or using
adhesives or by welding. Choice of a specific type of joint and joining
process depends on designer’s knowledge of joining techniques,
fabrication facilities, and state of development of material forms. Today,
welding is the most commonly used method of fabrication of structural
works, pressure vessels etc.
WELDED JOINTS
Welded joint has number of merits over other conventional
fabrication processes. They are
Welded joints provide leak proof joint.
Welding is more flexible and has numerous basic cost savings
over other forms of operations.
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Welding is 3 or 4 times stronger than other fabrication processes.
Welded parts are more resistant to shock and impact forces.
Capital equipment is less for welding compared to other
manufacturing processes.
Some of the demerits of welding are
Weld ability of some materials are not good.
Dismantling of joints is difficult. Hence welding is not preferred
where dismantling is necessary during service or maintenance.
Defects like cracks, porosity in welds affect strength of welds.
Welding may results in distortion of parts being jointed.
TYPES OF WELD JOINTS :
Weld joints can be classified as follows based on position.
Butt
Tee
Lap
Corner
Edge
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Types of Weld Joints
EDGE PREPARATION:
If the metal is thin, say 3mm, then it is possible to make a full
penetration weld between abutting edges. For thick sections, full
penetration can be achieved by beveling the weld edges or by providing
backing strip. Suitable bevel detail is selected to provide minimum weld
deposition and full penetration. Partial penetration weld joint can be
used for less critical services.
Normally, edge preparation is made by gas cutting / machining
for all C.S. materials. For S.S. materials, edge preparation is done by
either machining or plasma cutting.
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TYPE OF WELDS
For design purpose, welds can be divided into three basic types,
calling for different design methods and different design stresses. They
are groove, fillet and plug welds. The weld joint must be designed to
provide strength adequate to transfer the design stresses.
GROOVE WELDS
Groove welds provide better joint and takes more load. It can be
used in butt, tee or corner welds. A square butt weld is economical to
use, provided satisfactory soundness and strength can be achieved.
However, its use is limited by the thickness of joint. For thick joints,
edge of each member must be prepared to a particular geometry to
provide accessibility for welding and ensure desired soundness and
strength. In the interest of economy, that joint design should be selected
with root opening and groove angles that require smallest amount of
weld metal and still give sufficient accessibility for sound welds.
Welds in J- and U-groove joints may be used to minimize weld
metal requirements when the savings are sufficient to justify the more
costly preparation of the edges. This will be more useful in thick
section. Single bevel and J-groove welds are more difficult to weld than
V-and U-groove welds because one edge of the groove is vertical.
Selection of detail of weld groove depend upon the welding process,
type of power used and base material properties. A careful fit-up is
required for butt joints but slight mismatch may be permissible.
The strength of a groove weld is based on cross sectional area
subject to shear, tension or compression and allowable stress for the
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weld metal. The allowable stress for groove weld is generally same as
that of base material. Joint efficiency depends on the type of weld
examination, the welding procedure and type of load. Weld
reinforcement is a source of stress concentration and potential failure
under repetitive load. Removal of weld reinforcement increases fatigue
strength of weld.
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Complete Joint Penetration:
Groove welds with complete joint penetration are suitable for all
types of loadings, provided they meet the acceptance criteria for the
application. In most cases, a single groove weld is not considered to
have complete penetration unless it was made using a suitable backing
strip or a back weld was applied. In such cases, to ensure complete joint
penetration without backing strip, the root of first weld must be back
gouged to sound metal before making a weld pass on the other side.
Partial Joint Penetration:
It has an unwelded portion at the root of the weld. The unwelded
portions of groove-welded joints constitute a stress raiser having
significance where cyclic loads are applied transversely to the joint.
However, when the loads are applied to the welds axis, a higher stress
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range is permitted. Partially penetrated joints should not be exposed to
corrosive conditions. For design purpose, the effective throat is never
greater than the depth of joint penetrations.
FILLET WELDS:
Fillet welds are used in preference to groove weld for the sake of
economy. Fillet weld do not require edge preparation and fit up is easy.
Fillet weld size is measured by the length of the leg of largest
right triangle that may be inscribed within the fillet weld cross section.
The strength of fillet weld is based on the effective throat and the length
of the weld.
Stress concentration at the root or at the toe can cause failure
under variable loads. One sided fillet weld in tee or lap joining is
generally avoided because of a very low static and fatigue strength of
this weld. Face of fillet weld may vary from convex to concave to
reduce stress concentration.
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Stress induced in fillet-welded joints is complex because of the
eccentricity of the applied load, the weld shape and notch effects. They
consist of shear, tension and compressive stresses.
Fillet welds are used to join corner, tee and lap
joints. Fillet welds are generally used for transfer of shear forces
parallel to the axis of the weld and for transfer of static forces transverse
to the axis of the weld. If the load require a fillet weld of size 16 mm or
large, groove weld should be used possibly in combination with a fillet
weld to provide a required effective throat.
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Excessive fillet weld may be a major factor contributing to
an increase in welding cost, residual stresses and distortion. Fillet welds
may be designed with unequal leg sizes to provide the required effective
throat or the welded heat balance for complete fusion with unequal base
material thicknesses.
Plug welding:
A plug weld is circular weld made either by arc or gas welding
through one member of a lap or tee joint. Plug-weld holes in thin plates
are completely filled. They are only partially filled in heavier plates (i.e.
above 10 mm)
Plug welds are often used to fix corrosion
resistant lining to the base metal of pressure vessel. They are sometimes
used as strength welds in single lap joints, reinforcing pads or non-
pressure structural attachments and then only in addition to other types
of welds.
SIZING OF PLUG WELD:
ASME Sec. VIII Div.1 allows only 30% of the total load to
be carried by plug welds if they are used. The allowable working
load on a plug weld in shear or in tension can be computed by the
following code formula.
P = 0.63 (d - ¼) 2 Sa
Where
Sa = Allowable stress in tension of base materiald = the bottom diameter of weld hole, limited
to T + ¼" < d < 2T+ ¼" T = Plate thickness being welded.
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CORNER WELDS:
Corner welds are widely used in machine design. Typical
corner joint designs are illustrated in following figures.
Fig - A: This joint is difficult to position and usually requires fixturing.
This joint requires large amount of weld metal.
Fig - B: This joint is easy to assemble, does not require backing and
needs only about half of the weld metal required to make the joint
shown in Fig-A. But the joint has lower strength because effective throat
of weld is smaller.
Fig - C: This joint can provide the same total effective throat as with the
design shown in Fig- A but with half the weld metal.
Fig - D: This is suitable for thick section with partial penetration.
However this requires edge preparation.
Fig - E : This is suitable for thick section with deeper joint penetration.
Fig - F : This is ideal for critical or cycle service where sharp corners
are avoided.
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CLASSIFICATION OF WELDS :
Based on their reaction to loads, welds are classified as
Primary welds
Secondary welds
Transverse welds
Parallel welds
Primary welds: Primary welds are those that absorb full load at the
plane of the welds. Welds of these types must have same properties as
that of base materials.
Secondary welds: Secondary welds do not carry full load of connecting
members but must absorb forces, which are in the member at the point
of weld.
Transverse welds: Transverse welds are those that transmit tension and
compression force from one member to another.
Parallel welds: Parallel welds are those that transmit shear load from
one member to another.
Design Allowable stresses for welded joint:
Selection of proper allowable working stress or safety factor for
weld is an important aspect of design. Generally allowable stress of
weld material is expressed in terms of the strength of base material and
efficiency factor, E, to compensate for possible variation in weld
quality.
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ASME Sec.VIII Div.1 Code:
The joint efficiency depends on the type of weld and the degree of
radiographic examination. For butt-welded joints, joint efficiency shall
be as follows.
Joint efficiency
Spot radiography 0.85
Full radiography 1.0
No radiography 0.7
The allowable load on fillet welds connecting non pressure parts
to vessel pressure parts is equal to the product of the weld area based on
the minimum leg dimension, the allowable stress in tension of the
material being welded, Sa, and the joint efficiency of 55 %.
ASME Sec. VIII Div.2 -Code :
Full radiography is required for all pressure shell welds. The
strength of welds so inspected is considered to be the same as the
strength of base material.
Welds subject to fluctuating stresses must be designed and
evaluated according to design values based on fatigue analysis, as
described in Code Appendix-5.
AISC Specification :
This code is used for the design of structural construction. The
permissible design stress for groove welds with full penetration can be
taken the same as for the parent material if prescribed electrodes are
used.
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Allowable stress for fillet weld throat area is given in terms of the
specified strength of weld metal, depending in the electrode used. Here
the nominal composition of the electrode must be considered by the
designer where selecting the joint efficiency for the weld.
Indian Standard IS 816:
Butt weld shall be treated, as parent metal with thickness equal to
throat thickness and stress shall not exceed those permitted in parent
metal. For fillet and plug welds, stress shall not exceed 1100 kg/cm2.
For site weld made during erection of structural members, stress
shall be limited to 80% of those given above. If wind and earthquake
are taken into consideration, permissible stress may be increased by
25%.
Weld joint design:
Weld joint design primarily depends on load requirements.
Generally the following guidelines are to be followed for better design.
1. Select the joint design that requires the least amount of weld
metal, satisfying the required strength.
2. Use square-groove, partial joint penetration weld or intermittent
weld wherever possible.
3. Use lap and fillet welds instead of groove welds if fatigue is not a
design consideration.
4. Where repetitive loads are expected, full penetration groove welds
are to be used. Surfaces should be ground smooth to eliminate
possible minute discontinuities.
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5. Use double-V or U-groove instead of single-V or U-groove welds
on thick plates to reduce the amount of weld metal and to control
distortion.
6. For corner joints in thick plates where fillet welds are not
adequate, beveling both members should be considered to reduce
the tendency for lamellar tearing.
7. Design the assembly and the joints for good accessibility for
welding.
Stress concentration factor for welds:
Stress concentration in welds is due to geometry of welded joints,
defects and imperfections in the welds, and also the different
metallurgical structures of the weld metal, the metal in the heat affected
zone and the base metal.
The effect of these factors on stresses induced by steady loads in a
ductile weld material can be ignored. However, if the weld is hard and
brittle, or under shock, or fluctuating loads, the influence of stress
concentration becomes significant.
Welding symbols:
Weld symbol convey design requirements to the shop in a concise
manner. Welding symbol include the following.
Reference line
Arrow
Basic weld symbol
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Dimensions and other data
Supplementary symbols
Finish symbols
Specification, process or other reference
All the above elements need not be used unless required clarity.
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WELDING METHODS:
Assembly of parts by various welding process may be
adopted depending on codes requirements and customer requirements.
The following points may be taken as guidelines and further details are
to be had from welding technology:
1. Manual metal are welding may be adopted generally for all materials
(C.S, L.A.S, S.S etc.) of thickness from 1.5mm to 150mm. In case of
shell welding the minimum internal dia shall be 400mm.
2. Submerged arc welding may be adopted for materials like carbon
steel, low alloy steel & stainless steel of thickness above 10mm. In
case of shells welding the minimum dia should be 650mm.
3. 3.TIG welding is generally recommended for single side welding
joints where there is no access from the other side on materials like
stainless steel, low alloy steel, carbon steel & Aluminum etc. (Ex:
Pipe joints)
4. MIG welding is generally applicable similar as above recommended
for lengthy joints where there is free access for the machine.
5. Resistant welding is applicable for thick plate sections such as
flanges segments and joining thin plates such as bubble cap trays.
This is applicable only for non-pressure parts.
6. Electro slag welding is generally used for the welding longitudinal
seams only of carbon and low alloy steel of thickness 50mm to
450mm. In case of shells welded with this process the minimum
internal diameter should be 1000mm and the minimum. Length
should be 1.5 meters.
7. In case of points 1 to 4 points pre-heating may be required for
materials having thickness more than 25mm in case of carbon steel
and all materials in case of low alloy steel. No pre heating is required
in case of stainless
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TERMS TO PROCESS EQIPMENT INDUSTRY
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VOCABULARY OF TERMS TO PROCESS
EQUIPMENT INDUSTRY
I. MATERIALS:
1. Alloy steel: A steel containing one or more alloying elements as a
result of which it develops specific characteristics.
2. Asbestos: A material fibrous, of high melting point, low thermal
conductivity and Non-inflammable. It is used for filters, gaskets, fire
proof installations etc.
3. Carbon steel: A composite material obtained by firmly binding
together a carbon or alloy steel with a surface layer of another material
or alloy.
4. Cast steel: Originally this term was applied to differentiate crucible
steel from hot worked or commented bar. At present the term is used for
steel castings.
5. Mild steel: Carbon steel containing generally between 0.15 and 0.25%
carbon.
6. Stainless Steel: An alloy steel containing about 12% or more of
Chromium with or without Nickel together with other elements and is
characterized by its high resistance to corrosion.
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II. COMPONENTS:
1. Bar: A rolled or forged product of variable length, usually, square,
rectangular, hexagonal or circular in cross section.
2. Billet: A semi finished product obtained by forging, rolling or by
continuous casting usually square and not exceeding 125X125mm in
cross section with rounded corners, and is intended for further
processing into suitable finished product by forging or rerolling.
3. Bolt: A bolt is an external threaded fastener designed for insertion
through holes in assembled parts and is normally intended to be
tightened or released by torquing a nut.
4. Bloom: A semi finished forged, rolled or cast product intended for re
rolling or forging with a cross sectional area generally more than
160cm2.
5. Bright bar or wire: Bar or wire with a bright finish obtained by cold
Drawing, Machining, Grinding etc.
6. Flat: A bar of rectangular section with edges of controlled contour,
the width being greater than the thickness (thickness 3mm & over, width
400mm & below).
7. Girder or beam: A type of section, beam, simple or built up to takes
lateral stress.
8. Ingot: Castings of suitable shape or size intended for subsequent hot
working.
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9. Line Pipe: An American term usually associated with the oil industry
and applying to pipes used for conveyance of oil or natural gas,
excluding the pipes in the well.
10. Nozzles: Pipe lines witch bring the fluid to and from the tank are
attached to short pipe connections welded into the tank shell and these
connections are called Nozzles.
11. Plate: Product of rolling an ingot or slap in a plate mill. The cross
section is rectangular and over 5mm thick and the width is very much
greater than the thickness.
12. Pipe: Generally used to apply to tabular products where the
thickness is very small compared to the diameter commonly used for
pipe lines and connections for conveying fluid from point to point.
13. Rail: A type of section, straight and long used for track purpose for
Railways, Tramways, as well as for heavy mobile machinery running on
metal wheels.
14. Rod: A semi finished hot rolled product of relatively small cross
section and very great length produced in coil form. In rounds the usual
range of size in which wire rods are produced is from 5 to 14mm.
15. Screw: A Screw is an externally threaded fastener capable of being
inserted into holes in assembled parts of mating with performed internal
thread or forming its own thread and of being tightened or released by
torquing the head.
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16. Sheet: Plate of rolling, cross section is rectangular and thickness less
than 5mm, width is about 600mm and above. Usually available in coil
form.
17. Slab: A Semi finished rolled product intended for re-rolling or
forging. The cross section is rectangular, usually with a width more than
twice the thickness.
18. Strip: Flat rolled metal with greatest thickness being approximately
0.25 inch.
19. Stud: An externally threaded fastener without head which must be
assembled with a nut on side and screwed in tapped hole on the other
side or with two nuts to perform its intended service.
20. Tube: Generally used to apply to tabular products where the
thickness is considerably more compared to the diameter and commonly
used in Heat exchangers and Boilers (for heat transfer) and in machine
and air craft industries.
PIPE FITTINGS:
1. Branch: The outlet or inlet of fitting not in line with the run but which
may make any angle.
2. Bushing: A pipe fitting for the purpose of connecting a pipe with a
fitting of a large size being a hollow plug with internal and external
threads to suit the different diameters.
3. Close Nipple: Close Nipple is the one, the length of which is about
twice the length of slandered pipe thread and is without any shoulder.
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4. Coupling: A threaded sleeve used to connect two pipes. Also a forged
round piece outside of which is welded to the shell and inside threaded
to receive pipe or plug.
5. Cross: A pipe fitting with four branches arranged in pairs, each pair
on one axis and the axes are at right angles.
6. Elbow: A fitting that makes an angle between adjacent pipes. The
angle is always 90° unless other angle is stated.
7. Manifold: A fitting with numerous branches used convey fluids
between a large pipe and a several small pipes; a header for a coil.
8. Needle valve: A valve provided with a long tapering point in place of
the ordinary valve.
9. Nipple: A tabular fitting usually threaded on both ends and under 12
inches in length.
10. Plug: A threaded piece, used to close or blind the coupling.
11. Reducer: A fitting having a larger size at one end than at the other.
12. Short Nipple: One hose length is little greater than that of two
threaded lengths or some what larger than a close nipple. It always has
some un threaded portion between the two threads.
13. Tee: A fitting either cast or wrought, that has one side out let at right
angles to the Run.
14. Union: The usual trade term for a device used to connect two pipes.
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TESTING METHODS
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TESTING METHODS:
Types of tests:
1. Destructive tests &
2. Non-Destructive tests.
Destructive tests: These tests are required to determine the strength of
materials. Several destructive tests are available to determine the various
mechanical properties.
Non-Destructive tests: These tests are employed for finished products
to determine internal defects like blow holes, slag inclusions etc., and
surface defects.
Types of Destructive tests:
1. Static test: Load is applied gradually.
a) Tension test
b) Compression test
c) Shear test
d) Hardness test
e) Creep test
2. Impact test: Specimen is subjected to shock load.
a) Charpy impact test
b) Izod test
3. Cyclic test: Load is repeatedly varies in magnitude and direction
during the test.
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Tensile test:
Tensile test is widely used to find the behavior of material
when subjected to a slowly applied tensile load.
It is conducted on Universal Testing Machine (UTM) in which
load increased gradually up to fracture and stress-strain diagram is
obtained with the aid of instrument attached to the machine.
Compression test:
This test is conducted on UTM in a similar way as tensile
test, but the direction of load is reserved. Component subjected to a
compressive force does not deform uniformly. If the material is plastic
instead of brittle, it bulges as its mid section.
Shear test:
For the direct shear tests the portion of bar is clamped in a
device while the remaining portion is subjected to shear load by means
of suitable dies.
Hardness test:
Ability of material to resist indentation or penetration is called
hardness. The majority of hardness tests force a indentor into the surface
of the metal by means of applied load.
There are three types of hardness tests
1. Brinell hardness test :
The Brinell test consists of indenting the surface of metal by a
hardened steel ball under a load. The load is applied by a lever
system is placed on stage with its ground face upwards.
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2. Vicker’s hardness test :
The test is also called as Diamond pyramid hardness test. The
test is conducted on machines with an indenter of square based
Diamond pyramid of an angle of 136° between opposite faces.
3. Rockwell hardness test :
In Rockwell hardness test, the hardness is determined by the
depth of the penetration of an indenter, rather than by surface area of
indentation.
4. Charpy Impact Test:
An impact test in which a notched test piece supported at both
ends, is broken by a blow from a striker on the face opposite to and
immediately behind the notch, the energy absorbed in fracturing the
specimen being recorded.
5. Izod impact test:
The izod impact testing machine is commonly made with a
18Kg capacity. In this case a notched specimen is held in a vice in the
form of a cantilever and a heavy pendulum is allowed to strike the
specimen from a fixed height.
NON DESTRUCTIVE TESTING METHODS:
1. Visual inspection
2. Penetrating test
3. Magnetic detection test
4. Ultrasonic test
5. Radiography test
6. Spark test
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Visual inspection:
Often defects can be discovered by the naked eye or by using a
low power magnifying lens can be rectified or repaired.
Penetrating test:
This is the method of using a sensitive fluorescent penetrate to
locate cracks or porous areas on the surface of a metal which may not be
visible to naked eye.
Magnetic detection test:
Magnetic testing is used for detecting the surface flaws in Ferro
magnetic materials and alloys. The component under test is magnetized.
Ultrasonic test:
Used to inspect soundness of materials without destruction.
This method gives the exact location of the voids or inclusions found
from photo film obtained by passing radioactive rays through the metal
falling on the film. Extremely fine voids is cannot be detected by this
method.
Radiography test:
Radiography test is used to locate the internal defects in welded
products, castings and forgings. It uses radiation of short wave length
for detecting internal flaws.
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SOME IMPORTANT TESTING METHODS:
Bent test:
A test for ductility and soundness. It is carried out by bending a
test piece at the middle, over a specified radius generally by a steadily
applied load or by blow.
Drift test:
A test for plate is carried out by boring a hole of a given diameter
near the edge of the plate and enlarging by a conical tool having a
specified taper until either the specified increase in dia takes place or
cracking occurs.
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