3001 What is a pressure vessel?
Pressure vessel:
In chemical engg. various types of fluids, which are used for following purposes;

Storage

Chemical reactions taking place inside

Suppression of chemical reactions

Insulation (no transfer of heat)
Isolation from the surroundings (chemicals can be lethal)
3002 Write at least 5 basic industries which use pressure vessels.
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



Chemical industries like hydrogen manufacturing plant
Petro-chemical industries
Fertilizer industry
Nuclear power plants
Industries building submarines
3003 Classify pressure vessels based on shape and orientation.




According to geometric shapes: Cylindrical, Spherical, conical, etc
According to direction of the forces acting on the walls: Vessels subjected to internal pressure
&external pressure
According to the end head shape: Dished head, convex head, Flat head
According to its position during service: horizontal & vertical
According to type of service: Low pressure high pressure
3004 Draw a 2 or more sketches of pressure vessel showing each of the following components:
- Shell
- Head (Hemispherical, Elliptical, Torispherical, Flat)
- Cone (Straight & Knuckled)
- Nozzles (Self-reinforced, Non-integral reinforced, Non-reinforced)
- Flanges (Integral, loose)
- Supports (Saddle, Skirt, Lug-support)
Refer Deniss Moss & Brownell Young
3005 Write names of at least 5 major international PV design codes.
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
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
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









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ASME: American
ADM: German
PD5500: British
IBR: Indian
Stoomwezen: French
JIS: Japanese
BS 5500
AD Merkblätterasa
CODAP
AS 1210
CSA B51 in Canada
AS1210 in Australia
Lloyd's, Germanischer Lloyd
3006 Write at least 5 raw material product forms.
Plates
Sheets
Forgings
Bars
Beams
Pipes & Tubes
3007 Write 3 material names from each of the above material forms.
Refer II(D),
Carbon steel
Plates- SA516Cr70
SA516Cr60
Forging- SA105
Low Alloy steel
Plates-SA387Cr11 cl1
SA387Cr11 cl2
SA387Cr22Cl1
SA387Cr22 cl2
Forgings-SA336CrF11 cl1
SA336CrF11 cl2
Stainless steel.
Plates- SA240Cr304
SA240Cr3042
Forgings-SA132Cr304
SA240Cr3162
SA240Cr347
Bar: - 25Cr-22Ni-2Mo, SA 105M
Pipe: - AISI 316L, INCONEL 601, SA 234.
Tube: Fittings; Gasket: - Graphite, Plastic, and Rubber
Fasteners: - IS 1367, SA 193 GR B7, SA 194M GR.2H.
3008 What is design pressure/ design temperature?
Refer ASME code VII Div 1, UG- 20,21
It can be defined as minimum pressure used for designing the vessel, which is just greater than the
maximum operating pressure.
Operating pressure
<
Design pressure
(Absolute working pressure)
(Gauge pressure)
The pressure used in the design of a vessel. It is recommended to design a vessel and its parts for a
pressure 10% above its operating pressure. OR
A numerical value that defines the structural wind loading requirements (in pounds per square foot) for a
building and the components and cladding...
DESIGN TEMPERATURE
Similarly, design temperature is the minimum value of temperature used while designing the
vessel, which is just greater than the maximum operating temperature.
Operating temp.
<
Design temp.
The temperature that a system is designed to maintain (inside) or operate against (outside) under the
most extreme conditions
3009 What is wind/seismic load? How these are incorporated in PV design?
Refer Deniss moss, div 1
Understand how they affect the vessel.
WIND LOAD- Stresses are produced in a self-supporting vertical vessel by the action of wind. Wind
loading is a function of wind velocity, air density and shape of the tower.
SEISMIC LOAD- The seismic forces act to produce horizontal shear in vertical unguyed vessels. This
shear force in turn produces a bending moment about the base of the vessel.
3010 What is piping load?
Refer Deniss moss.
Piping load is the load acting on the walls of the pressure vessels. When a vessel, pipe, or other
component fails in a fluid transport or storage system, a thermal-hydraulic load probably exceeded
design limits.
1.
2.
3.
4.
5.
3011 Write at least 5 types of dead loads acting on PV.
Refer Brownell and Young.
Dead load acting on a vessel is determined by the weight and location of all interior attachments such as:
trays, overhead condensers, platforms, insulation, etc
Dead load due to wt. of shell
“
“
“
Insulation
“
“
“
Liquid inside the vessel
“
“
“
Internal attachments like trays
“
“
“
Minor attachments like manholes, nozzles…
3012 Write names of at least 3 commercially available softwares for PV design calculations.
- PV elite
- STAAD
- NOZPRO
3013 What is significance of corrosion allowance?
Refer Deniss moss and code.
It is the provision for possible deterioration due to the environment in which the vessel operates is
the responsibility of the designer.
The user or its designated agent shall specify corrosion allowances other than those required by the
rules of the division. Where corrosion allowances are not provided, this fact is not indicated on the data
report.
Vessels or a part of vessels subjected to thinning by corrosion, erosion or mechanical abrasion shall
have provision made for the desired life of the vessel by suitable increase in the thickness of the material
over that determined by the design formulas.
Material added for this purpose need not be of same thickness for the various parts of the vessels. No
additional thickness is provided if no corrosion is expected, owing to previous experience.
Telltale holes of 1.5mm-5mm are provided in the opposite s/f to that where deterioration is expected.
The corrosion allowance is material that can be gone and the equipment is still capable of working as
designed. You design the equipment to function correctly with that much material corroded away.
There are absolutely no standards. Every corrosion rate is different, and while there might be a standard
answer for some process that your company uses (like petroleum refining, for instance), don't mistake
that for a standard that cuts across different chemistry.
The life of the equipment will be the time it takes for the corrosion allowance to be eaten by the chemistry
at hand.
3014 What is significance of joint efficiency?
Refer Div 1, NonMandatory App-L.
Ratio of the strength of the joint compared to the strength of the base metal, this ratio is called joint
efficiency. An efficient joint is one that is just as strong as the base metal.
3015 What is hydrotest?
Div 1, UG-99
Hydrostatic Leak Testing requires that a component be completely filled with a liquid such as
water. Pressure is slowly applied to the liquid until the required pressure is reached. This pressure test is
held for the required time at which point the component is inspected visually to locate leaks.
A hydrotest is the common way in which leaks can be found in pressure vessels such as pipelines
and plumbing. Hydro testing is also a way in which a gas pressure vessel such as a gas cylinder or a
boiler is checked for leaks or flaws. Testing is very important because such containers can explode if
they fail when containing compressed gas.




i.
ii.
iii.
iv.
To be conducted on vessels after:
All fabrication is complete, except for operations, which could not be performed prior to the test.
All examinations are performed, except for to be performed after the test.
Vessels designed for int. pressure shall be subjected to hydrostatic test pressure, which at every point is
1.3times the maximum allowable working pressure to be marked on vessel multiplied by the lowest ratio
of stress value for test temperature on the vessel to the design temperature. All loading existing during
this test shall be considered.
Hydro test based on a calculated pressure may be used by agreement of user and manufacturer.
Combination units:
Pressure chambers of combination units that have been designed to operate independently shall
be hydrostatically tested as separate vessels. If the common elements of a combination unit are designed
for a larger differential pressure than the higher maximum allowable pressure to be marked on the
adjacent chamber, the hydro test shall subject the common elements to at least their design differential
pressure.
When pressure chambers of combination units have their common elements designed for the
maximum diff. Pr. That can possibly occur during startup, operation and shutdown. The differential
pressure is less than the higher pressure in adjacent chamber. The common elements can be subjected
to hydrostatic test pr., which is 1.3 times the diff. Pr. to be marked on the unit.
Test for common elements & their inspection. Care must be taken to limit the differential pr. to the pr
used for testing.
Single wall vessels & Chambers of multichamber- designed for vacuum or partial vacuum – subjected to
int. hydro test or pneumatic test. Pressure should be less than 1.3 times the difference between normal
atm. pr. and the minimum design int. absolute pr.
Inspection shall be made on all the joints and connections.
For inspection pr. not less than test pr. /1.3
Leakage might occur at the temporary test closures that are intended for weld connections. Leakages
are not allowed at time of visual inspections. Leakage from temporary seals shall be directed away to
avoid masking leaks from other joints.
The visual inspection of joints and connections for leaks at test pr./1.3 are waived provided.
A suitable gas test is applied.
Substitution of gas leak test is by agreement of manufacturer and inspector.
All welded seams, which will be hidden by assembly, are given a visual examination for
workmanship prior to assembly.
The vessels will not contain a lethal substance.
Any nonhazardous liquid at any temperature below its boiling point may be used for hydro test.
Combustible liquid having flash point less than 43 C. Metal temperature during test be 17C-48C.
Vents shall be provided at all high points of the vessel in the position it is to be tested to purge possible
air pockets while vessels is filing.
Before applying pr., test equipment is tested to see that it is tight and all low pressure filling lines and
other appurtenances that should not be subjected to test pr. are disconnected.
Vessels, except for those in lethal service, may be painted or otherwise coated either int. or ext.
3016 What is PWHT, SR?
Div 1, UW-40.
3017 What is flange rating?
ASME 16.5



1.
2.
3.
4.
5.
6.
3018 What is local load calculation? Name standards for performing these calculations.
Deniss moss.
Local loads are confined to a small portion of the vessel. They are caused due to reactions from support,
internals, attached equipment, attached piping
Radial load- inward or outward
Shear load- longitudinal or circumferential
Torsional load
Most significant findings are developed by P.P.Bijlaard of Cornell University.
Methods:
Roark technical note#806
Ring analysis
Elastic foundation method
Bijlaard analysis
WRC bulletin#107
Finite element analysis
3019 Draw sketch of skirt support base ring indicating important parts. (base ring, compression ring,..)
Brownell and Young
3020 What is NDT?
Div 1, UG- 103.
Nondestructive testing (NDT), also called nondestructive examination (NDE) and nondestructive
inspection (NDI), is testing that does not destroy the test object. NDE is vital for constructing and
maintaining all types of components and structures. To detect different defects such as cracking and
corrosion, there are different methods of testing available, such as X-ray (where cracks show up on the
film) and ultrasound (where cracks show up as an echo blip on the screen). This article is aimed mainly at
industrial NDT, but many of the methods described here can be used to test the human body. In fact
methods from the medical field have often been adapted for industrial use, as was the case with Phased
array ultrasonics and Computed radiography.
While destructive testing usually provides a more reliable assessment of the state of the test object,
destruction of the test object usually makes this type of test more costly to the test object's owner than
nondestructive testing. Destructive testing is also inappropriate in many circumstances, such as forensic
investigation. That there is a tradeoff between the cost of the test and its reliability favors a strategy in
which most test objects are inspected nondestructively; destructive testing is performed on a sampling
of test objects that is drawn randomly for the purpose of characterizing the testing reliability of the
nondestructive test.
3021 Explain meaning of RT, UT, MP, DP.
Div 1
RT
Radiographic Testing (RT), or industrial radiography, is a nondestructive testing (NDT) method of
inspecting materials for hidden flaws by using the ability of short wavelength electromagnetic radiation
(high energy photons) to penetrate various materials.
Either an X-ray machine or a radioactive source (Ir-192, Co-60, or in rare cases Cs-137) can be used
as a source of photons. Neutron radiographic testing (NR) is a variant of radiographic testing which uses
neutrons instead of photons to penetrate materials. This can see very different things from X-rays,
because neutrons can pass with ease through lead and steel but are stopped by plastics, water and oils.
Since the amount of radiation emerging from the opposite side of the material can be detected and
measured, variations in this amount (or intensity) of radiation are used to determine thickness or
composition of material. Penetrating radiations are those restricted to that part of the electromagnetic
spectrum of wavelength less than about 10 nanometres.
Inspection of welds
The beam of radiation must be directed to the middle of the section under examination and must be
normal to the material surface at that point, except in special techniques where known defects are best
revealed by a different alignment of the beam. The length of weld under examination for each exposure
shall be such that the thickness of the material at the diagnostic extremities, measured in the direction of
the incident beam, does not exceed the actual thickness at that point by more than 6%. The specimen to
be inspected is placed between the source of radiation and the detecting device, usually the film in a light
tight holder or cassette, and the radiation is allowed to penetrate the part for the required length of time
to be adequately recorded.
The result is a two-dimensional projection of the part onto the film, producing a latent image of varying
densities according to the amount of radiation reaching each area. It is known as a radiograph, as
distinct from a photograph produced by light. Because film is cumulative in its response (the exposure
increasing as it absorbs more radiation), relatively weak radiation can be detected by prolonging the
exposure until the film can record an image that will be visible after development. The radiograph is
examined as a negative, without printing as a positive as in photography. This is because, in printing,
some of the detail is always lost and no useful purpose is served.
Before commencing a radiographic examination, it is always advisable to examine the component with
one's own eyes, to eliminate any possible external defects. If the surface of a weld is too irregular, it may
be desirable to grind it to obtain a smooth finish, but this is likely to be limited to those cases in which the
surface irregularities (which will be visible on the radiograph) may make detecting internal defects
difficult.
After this visual examination, the operator will have a clear idea of the possibilities of access to the
two faces of the weld, which is important both for the setting up of the equipment and for the choice of
the most appropriate technique.
Defects such as delaminations and planar cracks are difficult to detect using radiography, which is
why penetrants are often used to enhance the contrast in the detection of such defects. Penetrants used
include silver nitrate, zinc iodide, chloroform and diiodomethane. Choice of the penetrant is determined
by the ease with which it can penetrate the cracks and also with which it can be removed. Diiodomethane
has the advantages of high opacity, ease of penetration, and ease of removal because it evaporates
relatively quickly. However, it can cause skin burns.
UT- Ultrasonic testing
Basic Principles Ultrasonic Pulse Echo equipment generates high voltage electrical pulses. These
pulses are applied to the Transducer (Probe), which converts them into mechanical vibrations (sound
energy at high frequency i.e. Ultrasonic sound energy > 20,000 cycles per second) that are transmitted
into the material being tested. The reflected sound energy either from the back surface or from
discontinuities is again converted into electrical pulses by the transducer and is displayed on the CRT
(Cathode ray tube)
APPLICATION Plates are usually tested for laminations using normal beam probes.
For special application such as Nuclear / Aerospace, plates are also tested with angle beam.
Forgings depending on their shape and size are tested using normal as well as angle beam probes.
Weld overlay is usually tested with twin crystal normal beam probes. In some special application angle
beam scanning is also carried out.
Welds such as butt / nozzle welds are tested both with normal & angle beam probes
Frequency of sound energy used in general for contact testing is up to 5 MHz, whereas in immersion
testing the frequency used may be as high as 25 MHz.
Probe angles used in general in angle beam examination are 45, 60 & 70 Deg. Some other angles such
as 35, 80 deg etc are also used for some special applications depending on the geometry of the
specimen.
In general normal beam testing is carried out using longitudinal mode, whereas shear waves are used in
case of angle beam scanning. But in some cases like angle beam examination of weld overlay,
longitudinal waves are used for better penetration.
ADVANTAGES
•Testing can be carried out with one side access.
•Any thickness on higher side can be tested (Superior
penetrating power).
•Results are immediate.
•Exact depth and locations of flaws can be estimated.
•Compact and portable equipments are available
LIMITATIONS
Highly skilled and trained personnel are required.
•Coarse grain weld material like Austenitic stainless steel & Nickel based non-ferrous welds are
difficult to test.
•Equipment cost is very high for automated testing with recording / imaging facility.
MP-- (Magnetic Particle Test)
This is a nondestructive method of inspection to determine the existence and extent of surface and
near surface cracks in ferromagnetic materials. Finely divided magnetic particles, applied to a part
during magnetization, are attracted to any magnetic-leakage fields created by discontinuities. The
magnetic particles are attracted to the discontinuous areas and outline these areas so surface and near
surface cracks can be identified.
DP- (Dye Penetrant Test)
This is a method that locates discontinuities open on the surface of a metal component. First, a
penetrating dye is allowed to infiltrate the discontinuity. Next, the excess penetrant is removed, and then
a developing agent is applied. The developing agent causes the penetrant to weep back out of the
discontinuity and register as an indication. Penetrant inspections are generally suitable for both ferrous
and non-ferrous materials, but limited to the detection of open surface discontinuities in non-porous
solids.
3022 What is PMI & why is it carried out?
Positive Material Identification.
Positive Material Identification (PMI) is one of the more specialized non-destructive testing methods. With
Positive Material Identification the alloy composition of materials can be determined. PMI is particularly
used for high-quality metals like stainless steel and high alloy metals. While engineers push the
boundaries of material capacities to their limits in the design, assurance that the proper material is used
becomes ever more important.
3023 Explain difference between furnace PWHT & LSR.
Find out how they are carried out and when are they required.
3024 What is weld edge preparation?
Brownell and Young
3025 What is QAP, Inspection plan?
-The purpose of the Quality Assurance (QA) plan is to ensure that delivered products satisfy contractual
agreements, meet or exceed quality standards, and comply with approved processes.
Program Level QA plan and special characteristics appropriate to the task are required for completion of
the Project Level QA plan(s).
3026 Draw transition detail of joining 2 pressure vessel parts of different thickness
( Find out about taper forming while welding head to shell from div 1 )
3027 What are tolerances on formed head?
Div 1, UG-81 And also UG-80
Tolerance on formed heads
 Ovality or out-of-roundness
 Shape (under or overcrowning)
Ovality : Dmax – Dmin ≤ 1%D, where D is the nominal dia
Incase of any opening from shell- if c/s passes through opening
Dmin
Dmax
Dmax –Dmin ≤ 1%D + 2%d
D
d
For longitudinal lap joints permissible difference in dia. is increased by nominal thickness of plate.
Shape:
For overcrowning – 1 ¼ %D
For under crowning- 5/8%D
Tolerances are less for under crowning because deeper the head pressure acting is less. Shallower the
head pressure is more.
For external pressure acting on the vessel mainly depends on the shape of the vessel. For a vessel to withstand
higher external pressure, its diameter should be as minimum as possible, thickness should be more & effective
length of the vessel should be low.
( also read about permissible deviation “e”)
3028 What is pipe schedule? What is wall thickness, ID and weight per meter for 4" sch XXS pipe?
Ask about pipe schedule from any designer
3029 What is ARM used for ordering of materials ? Explain major sections of ARM.
(refer my file).
ARM: - Additional Requirement of Materials.
Requirements that are to be supplement (i.e. are in additional to) the requirement of the material specification
are introduced here.
Standard ARM codes are classified as follows according to their requirement specific no. is given instead of full
description.
1. Inspection & Certification at Manufacturers.
2. Process of steel making.
3. Condition.
4. Chemical composition.
5. Non-Destructive Examination (NDE)
6. Finish
7. Test coupon to be subjected to.
8. Type of certificate.
9. Annexure & specific Arm’s for each job.
3030 Why simulation heat treatment is needed to be specified in ARM?
Find out about MTC (material test coupon)
When material undergoes a no. of cycle of heat treatment, its mechanical properties get deteriorated.
Hence to check whether these properties are within allowable limits to sustain pressure loads simulation
PWHT is specified in ARM.
3031 How impact strength value is specified?
Impact strength value is specified in material annexure (ARM).
It is specified at specific temperature.
Impact strength- the ability of a material to withstand shock loading. The work done to fracture, under
shock loading, a test specimen in a specified manner.
Find out about impact testing and method of carrying out. (Refer any book on material science which
also has testing of materials)
3032 What is hot tensile test?
Tensile test carried out at elevated temperatures. (Read about tensile test from book on materials)
3033 Explain following heat treatment terms: Normalizing, Tempering, Annealing, Accelerated cooling,
Quenching
(Refer books from R&D library).
a. NORMALISING
Normalizing; - When an annealed part is removed from the furnace and allowed to cool in air, it is called a
"normalizing" heat treatment. It is a heat-treating process that results in a relatively uniform
microstructure.
b. TEMPERING
Tempering: - It is a heat treatment technique for metals and alloys. In steels, tempering is done to
"toughen" the metal by transforming brittle martensite into bainite or a combination of ferrite and
commentate
c. QUENCHING
- Hot metal parts (gears, plates, slabs, billets, etc) are quenched using air, water, oil, or liquid polymers to
obtain certain hardness and mechanical properties requirements. Cooling at a sufficiently high rate to
avoid undesirable internal microstructure as well as to ensure uniform mechanical properties, minimize
residual stresses, and avoid warpage generally does quenching. Quenching is a complex process and
involves three distinct stages: formation of a vapor film around the parts, boiling phase involving nucleate
boiling, and convection phase. The most critical of these stages is the vapor phase as a vapor blanket
around the parts reduces the efficiency. This vapor blanket can be broken by sufficient agitation near the
parts.
Hardening and tempering (quenching and tempering)

To harden by quenching, a metal (usually steel or cast iron) must be heated into the austenitic crystal
phase and then quickly cooled. Depending on the alloy and other considerations (such as concern for
maximum hardness vs. cracking and distortion), cooling may be done with forced air or other gas (such
as nitrogen), oil, polymer dissolved in water, or brine. Upon being rapidly cooled, the portion of austenite
(dependent on alloy composition) will transform to martensite, a hard brittle crystalline structure.

Untempered martensite, while very hard and strong, is too brittle to be useful for most applications. A
method for alleviating this problem is called tempering. Most applications require that quenched parts be
tempered (heat treated at a low temperature, often three hundred degree Fahrenheit or one hundred fifty
degrees Celsius) to impart some toughness. Higher tempering temperatures (may be up to thirteen
hundred degrees Fahrenheit, depending on alloy and application) are sometimes used to impart further
ductility, although some yield strength is lost.
] Precipitation hardening

Some metals are classified as precipitation hardening metals. When a precipitation-hardening alloy is
quenched, its alloying elements will be trapped in solution, resulting in a soft metal. Aging a
"solutionized" metal will allow the alloying elements to diffuse through the microstructure and form
intermetallic particles. These intermetallic particles will nucleate and fall out of solution and act as a
reinforcing phase, thereby increasing the strength of the alloy. Alloys may age "naturally" meaning that
the precipitates form at room temperature, or they may age "artificially" when precipitates only form at
elevated temperatures. In some applications, naturally aging alloys may be stored in a freezer to prevent
hardening until after further operations - assembly of rivets, for example, may be easier with a softer
part.

Examples of precipitation hardening alloys include 2000 series, 6000 series, and 7000 series aluminium
alloy, as well as some super alloys and some stainless steels.
d. ANNEALING
Annealing is a technique used to recover cold work and relax stresses within a metal. Annealing typically
results in a soft, ductile metal. When an annealed part is allowed to cool in the furnace, it is called a "full
anneal" heat treatment. When an annealed part is removed from the furnace and allowed to cool in air, it is
called a "normalizing" heat treatment. During annealing, small grains recrystallize to form larger grains. In
precipitation hardening alloys, precipitates dissolve into the matrix, "solutionizing" the alloy.

Typical annealing processes include, "normalizing", "stress relief" annealing to recover cold work, and
full annealing.
e. ACCELERATED COOLING
Controlled forced cooling from above the austenite transformation for fine pearlite metallurgical structure.
Apparatus consist of cooling headers utilizing a liquid cooling medium such as unheated water.
3034 What is fine grain steel? How it is related to impact strength?
(Find out about ASTM no. Its relation to impact strength is something to do with brittleness.)
Higher the ASTM no., finer is the grain structure.
For ASTM no. from 1-4: grain structure is coarse, while ASTM no. 5 onwards it is fine.
3035 Write at least 5 types of gaskets.
Brownell and Young.
A gasket is a mechanical seal that fills the space between two objects, generally to prevent leakage
between the two objects while under compression. Gaskets save money by allowing less precise mating
surfaces on machine parts, which can use a gasket to fill irregularities.
Gaskets are commonly produced by cutting from sheet materials, such as gasket paper, rubber, silicone,
metal, cork, felt, Neoprene, fiberglass, or a plastic polymer. Gaskets for specific applications may
contain asbestos. It is usually desirable that the gasket be made from a material that is to some degree
compressible such that it tightly fills the space it is designed for, including any slight irregularities.
Types: flat-ring , laminated , serrated metal , corrugated , ring-joint.
3036 Draw a sketch of weld neck flange indicating following: large/small end hub, G, PCD, hub height,
gasket face, flange thickness.
3037 Classify materials based on their composition.
Refer ASME div IID
3038 Write full names & current edition of following standards: ASME B16.5, B16.9, B16.11, B16.20,
B16.47.
Refer any code starting pages, table U-3
ASME B16.5- ASME-B-16-5-1996 Pipe flanges and flanged fittings NPS 1/2 through NPS 24
B16.9 factory-made wrought butt welding fittings
ASME-B-16-11-1996 Forged fittings socket welding and threaded (Revision of ASME-B-16-11- 1991
B16.20 ASME-B-16.20-1993 Metallic gaskets for pipe flanges-ring-joint, spiral-wound, and jacketed
B 16.47 ASME-B16.47 - 1990 and Addenda B16.47a - 1991 Large diameter steel flange
3039 Explain cold, warm & hot rolling operations.
Library.
Cold rolling: It is a metal working process in which metal is deformed by passing it through rollers at a
temperature below its recrystallization temperature. Cold rolling increases the yield strength and hardness of a
metal by introducing defects into the metal's crystal structure. These defects prevent further slip and can
reduce the grain size of the metal, resulting in Hall-Petch hardening.
Cold rolling is most often used to decrease the thickness of plate and sheet metal.
Warm rolling: The objective of warm rolling is micro structural refinement, which may lead to increases in
rolling contact fatigue life. A consequence of this refinement is that the austenitizing temperature used in the
final hardening cycle should be reduced.
Hot rolling: The metallurgical process of Hot rolling, used mainly to produce sheet metal or simple cross
sections from billets describes the method of when industrial metal is passed or deformed between a set of
work rolls and the temperature of the metal is generally above its recrystallization temperature, as opposed to
cold rolling, which takes place below this temperature. Hot rolling permits large deformations of the metal to be
achieved with a low number of rolling cycles.
Because the metal is worked before crystal structures have formed, this process does not itself affect its micro
structural properties. Hot rolling is primarily concerned with manipulating material shape and geometry rather
than mechanical properties. This is achieved by heating a component or material to its upper critical
temperature and then applying controlled load, which forms the material to a desired specification or size.
Mechanical properties of the material in its final 'as-rolled' form are a function of:

Material chemistry,

Reheat temperature,

Rate of temperature decrease during deformation,

Rate of deformation,

Heat of deformation,

Total reduction,

Recovery time,

Recrystallisation time, and
Subsequent rate of cooling after deformation.
3040 Write meaning of following terms: CRS, BOM, MDR, DCRQ, NCR, Seam-number.
CRS- CRITICAL REQUIREMENT SHEET
This is made in the beginning, to provide the requirement of :
 Long lead-cycle items
 High value items-import items
BOM- BILL OF MATERIAL
MDR- MANUFACTURER’S DESIGN REPORT
MDR typesMDR1- Pressure part calculations
MDR2- Wind & seismic calculations
MDR3- Nozzle local loads
MDR4- Lifting calculations
DCRQ- DESIGN CHANGE REQUEST
1. Change in design because of desired material not available.
2. Drwg. Errors such as,
 Wrong dimensions
 Dimensions missing
 Part no. missing
NCR –NON-CONFIRMATIVE REPORT.
Suppose there is some non-reparable change in the vessel during manufacturing
Eg. Hole of 20 dia instead of 18 dia., but is still acceptable. Has to be specified in the NCR. Now it can be
accepted by the inspection party as well as customer.