Fabrication and determination of critical thickness of spherical objects

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[Company name] [Company address]
[Document title]

FABRICATION AND DITERMINATION OF CRITICAL
THICKNESS ONSPHERICAL OBJECTS
By
Anurag kumar Tiwari (1002940016)
Ashwini kumar verma (1002940024)
Emam raza (1002940032)
Pankaj bernwal(1002940060)
Submitted to the Department of Mechanical Engineering in partial
full fill of the requirements for the degree of Bachelor of Technology
In Mechanical Engineering
Krishna Institute of Engineering and Technology
U.P Technical University May, 2014

TABLE OF CONTENTS
Declaration
1.
Certificate
2.
Acknowledgment
3.
Abstract
4.
List of table
5.
List of figure
6.
Chapter 1: INTRODUCTION
1.1S

DECLARATION
We hereby declare that this submission is our own work and that, to the best of our
knowledge and belief, it contains no material previously published or written by another
person nor material which to a substantial extent has been accepted for the award of any
other degree or diploma of the university or other institute of higher learning, except where
due acknowledgment has been made in the text.
Signature
Anurag kumar tiwari
(1002940016)
Ashwini kumar
verma (1002940024)
Emam raza
(1002940032)

Pankaj beranwal
(1002940061)
CERTIFICATE
This is to certify that Project Report entitled “FABRICATION AND
DETERMINATION OF CRITICAL THICKNESS OF SPHERICAL OBJECTS”
which is submitted by Anurag Tiwari, Ashwini kumar verma, Emam raza, Pankaj
baranwal in partial fulfilment of the requirement for the award of degree B. Tech. in
Department of Mechanical Engineering of U. P. Technical University, is a record of the
candidate own work carried out by him under my/our supervision. The matter
embodied in this thesis is original and has not been submitted for the award of any
other degree.
Date:
Mr NITIN
SHARMA
Assistant
Professor,
Department of Mechanical
Engineering,
K.I.E.T.,
Ghaziabad

ACKNOWLEDGEMENT
It gives us a great sense of pleasure to present the report of the B. Tech Project undertaken
during B. Tech. Final Year. We owe special debt of gratitude to Mr NITIN SHARMA,
Department of Mechanical Engineering, College, KIET Ghaziabad for his constant support
and guidance throughout the course of our work. His sincerity, thoroughness and
perseverance have been a constant source of inspiration for us. It is only his cognizant
efforts that our endeavours have seen light of the day.
We also take the opportunity to acknowledge the contribution of Dr K.L.A. Khan, Head,
Department of Mechanical Engineering, College, KIET Ghaziabad for his full support and
assistance during the development of the project.
We also do not like to miss the opportunity to acknowledge the contribution of all faculty
members of the department for their kind assistance and cooperation during the development
of our project. Last but not the least, we acknowledge our friends for their contribution in
the completion of the project.
Anurag Tiwari (1002940016)
Ashwani kumar verma (1002940024)
Emam raza(1002940032)

Pankaj barnwal (1002940060)
ABSTRACT
The critical radius effect is an interesting phenomenon of heat transfer in insulated circular
solids. Insulating a cylinder or sphere larger than the critical radius has the expected effect of
retarding heat loss. If the radius of cylinder or sphere is smaller than the critical radius,
adding insulation will actually increase heat loss. In present project a stainless steel sphere is
heated by means of a heater 300W 240V which heats uniformly the SS sphere. This SS
sphere is bounded by plaster of Paris. By heating of stainless steel sphere gets heated.
Trappings for thermocouple are given along insulation for plaster of Paris. Finally critical
radius of insulation for a sphere is determined.

Table No. Table Description Page No.

LIST OF FIGURES
Figure
No.
Figure Description Page
NO.

CHAPTER 1
INTRODUCTION:
THE critical thickness of insulation or coating is very important in many thermal
applications. It is maximum thickness of insulator over the sphere at which we obtain
maximum heat transfer rate. When radius of the insulator is increased beyond a certain limit
the heat transfer rate instead of increasing start to decrease. The critical radius of insulation
dependent on thermal conductivity of the insulation (k) and the external convection heat

transfer coefficient (h). Adding more insulation to a wall or to the attic always decreases
heat transfer since the heat transfer area is constant, and adding insulation always increases
the thermal resistance of the wall without increasing the convection resistance. The heat
transfer from the sphere may increase or decrease, depending on which (conduction or
convection) effect dominates.The applications for a spherical surface which is coated with
layers of different material or insulation, and in a radiation and convection environment, has
wide application in industry. Industrial application includes use in combustion of powdered
coal or pulverized coal covered with an ash layer, heat transfer in micro ball bearings coated
with a high hardness layer, and insulation of a melting pot. In nanoparticle thermotherapy,
convection and conduction heat transfer to nearby tissue is the dominant mechanism of heat
transfer, where maximum heat transfer is a function of external convection, coating thermal
conductivity, and coating thickness.
Energy keeps the world in motion. Without energy, everything would come to a standstill.
The global economy is dependent upon a secure, efficient supply of energy.
Over eighty percent of the energy currently being consumed however is obtained from non-
renewable resources. Energy resources are becoming increasingly scarce, whilst at the same
time the demand for energy is exploding. This means that owners, designers and operators
of large, industrial plants are challenged with the task of reducing their energy consumption
as much as possible in order to ensure the long term sustainability of their operations.
The time for making excuses for poor energy efficiency is past, because nowadays there are
a great many efficient insulation systems that enable scarce energy reserves to be put to the
best possible use. The Rockwool
Technical Insulation Process Manual illustrates these systems both theoretically and
practically.
The process manual is aimed at designers, installers and managers of industrial plants and
provides an overview of the possible modern insulation techniques for, by way of example,
chemical or petrochemical installations and power stations. Based on current standards and
regulations the manual provides accessible, practical guidelines for the implementation of
numerous insulation applications.
In addition, the right insulation keeps temperatures, for example in pipes and storage tanks,
within strict tolerances, thereby ensuring reliable process efficiency.

At the same time, adequate insulation protects the plant itself. Modern insulating materials
can thoroughly protect plant components from moisture and associated corrosion.
Installation and process maintenance costs can be reduced considerably and the effective
lifetime of industrial plants can be successfully maximised.
Furthermore, industrial insulation also provides a significant contribution to personal
protection. Optimum insulation reduces process temperatures and noise in the industrial
environment to an acceptable level, to the limits generally regarded in the industry to be
those required for a safe and comfortable working environment.
Scientists are interested in coating nanoparticles with different material films. Such coatings
have a strong effect on nanoparticle applications. It is very important to control and
understand the temperature of nanoparticles when used in thermotherapy. Nanoparticle
thermotherapy is known as magnetic nanoparticle therapy where induced localized
hyperthermia is used to kill or weaken tumour cells. The ability to manipulate the surface
properties of the nanoparticles through deposition of one or more material layers can greatly
enhance their effectiveness. The variation in coating thickness could have a big influence on
temperature distribution within a nanoparticle fluid. Different coating materials are used in
nanoparticle thermotherapy to assure a homogenous low viscosity fluid allowing good
penetration of the tumour cell with late detection by the immune system.
The use of the critical radius for radial heat conduction in thermal insulation systems has
been widely reported in the literature.
One of the early works that investigated the critical thickness using a numerical solution was
presented by Simmons. to minimize the total heat loss from the wall to the surroundings.
Recently, scientists considered the effects of a biocompatible coating layer on the magnetic
properties of super paramagnetic iron oxide nanoparticles. Similarly, it is important to
understand the effect of such coatings on the heat transfer and temperature distribution
within a nanoparticle fluid mainly used for thermotherapy applications. Thermotherapy is
used as a cancer treatment to kill or weaken tumor cells, with negligible effects on healthy
cells. Tumor cells, with a disorganized and compact vascular structure, have difficulty
dissipating heat. Therefore, hyperthermia may cause cancerous cells to undergo apoptosis
(i.e., cell selfdestruction) due to the applied heat, whereas healthy cells can more easily
maintain a normal temperature by better heat dissipation.

Metal nanoparticles efficiently generate heat in the presence of electromagnetic radiation. In
this study, the authors present the effect of a coating on heat transfer from a single spherical
particle. Sahin and Kalyon presented an analytical study on the critical radius of insulation
for a circular tube subjected to radiative and convective heat transfer. They presented three
closed form solutions for insulation in cylindrical coordinates. Lee et al. used regular
polygon top solid wedge thermal resistance to characterize the heat transfer for an insulated
regular polyhedron. Lee et al. showed that the thermal resistance of the inner convection
term and the body conduction term cannot be neglected, especially in situations with small
body sizes or large outer convection coefficients.
Following specific objectives were undertaken:
1).Understand the concept of critical thickness of insulation.
2).Graphically represent the variation of heat loss against critical radius.
3). Apply the concept of critical thickness of insulation to decide appropriate thickness.
4). Thickness of insulation for practical applications.
5). Develop setup of finding the critical thickness of spherical object.
Concept of heat transfer:
Heat transfer describes the exchange of thermal energy, between physical systems depending
on the temperature and pressure, by dissipating heat. Heat transfer always occurs from a
region of high temperature to another region of lower temperature. Determining the rates of
heat transfer to or from a system and thus the time of cooling or heating, as well as the
variation of temperature, is the subject of heat transfer.
The basic requirement for heat transfer is the presence of temperature difference. There can
be no net heat transfer between two mediums that are at the same temperature. The
temperature difference is the driving force for heat transfer, just as the voltage difference is
the driving force for electric current flow and pressure difference is the driving force for
fluid flow. The rate of heat transfer in a certain direction depends on the magnitude of the
temperature gradient (the temperature difference per unit length or the rate of change of
temperature) in that direction. The larger the temperature gradient, the higher the rate of heat

transfer.
Figure.3
2.2 Modes of Heat Transfer
The fundamental modes of heat transfer are conduction or diffusion, convection, advection
and radiation.
2.2.1 Conduction
On a microscopic scale, heat conduction occurs as hot, rapidly moving or vibrating atoms
and molecules interact with neighbouring atoms and molecules, transferring some of their
energy (heat) to these neighbouring particles. In other words, heat is transferred by
conduction when adjacent atoms vibrate against one another, or as electrons move from one
atom to another. Conduction is the most significant means of heat transfer within a solid or
between solid objects in thermal contact. Fluids—especially gases—are less
conductive. Thermal contact conductance is the study of heat conduction between solid
bodies in contact.
Steady state conduction (see Fourier's law) is a form of conduction that happens when the
temperature difference driving the conduction is constant, so that after an equilibration time,
the spatial distribution of temperatures in the conducting object does not change any

further. In steady state conduction, the amount of heat entering a section is equal to amount
of heat coming out.
Transient conduction (see Heat equation) occurs when the temperature within an object
changes as a function of time. Analysis of transient systems is more complex and often calls
for the application of approximation theories or numerical analysis by computer.
2.2.2 Convection
Convective heat transfer, or convection, is the transfer of heat from one place to another by
the movement of fluids, a process that is essentially the transfer of heat via mass transfer.
Bulk motion of fluid enhances heat transfer in many physical situations, such as (for
example) between a solid surface and the fluid. Convection is usually the dominant form of
heat transfer in liquids and gases.
Free, or natural, convection occurs when bulk fluid motions (steams and currents) are caused
by buoyancy forces that result from density variations due to variations of temperature in the
fluid. Forced convection is a term used when the streams and currents in the fluid are

induced by external means—such as fans, stirrers, and pumps—creating an artificially
induced convection current.
2.2.3 Radiation
Thermal radiations occurs through a vacuum or any transparent medium (solid or fluid). It is
the transfer of energy by means of photons in electromagnetic waves governed by the same
laws.
Thermal radiation is a direct result of the random movements of atoms and molecules in
matter. Since these atoms and molecules are composed of charged particles (protons and
electrons), their movement results in the emission of electromagnetic radiation, which
carries energy away from the surface.

Figure of radiation
The Stefan-Boltzmann equation, which describes the rate of transfer of radiant energy, is as
follows for an object in a vacuum:
For radiation transfer between two objects, the equation is as follows:
Where
Q = heat transfer rate in W
T = is the absolute temperature (in Kelvin or Rankin)
€ = emissivity (unity for a black body)
σ = is the Stefan-Boltzmann constant.

2.3 Fourier’s Law of Heat Conduction
The law of heat conduction, also known as Fourier's law, states that the time rate of heat
transfer through a material is proportional to the negative gradient in the temperature and to
the area, at right angles to that gradient, through which the heat flows.
Where,
Q = is the rate of conduction heat transfer.
K = is a constant called thermal conductivity of the material.
X=thickness of wall.
dT/dx = is the temperature gradient and is a constant since temperature through the wall
varies linearly with x.That is, the temperature distribution in the wall under steady state
conditions is a straight line.
Here negative sign shows that the heat transfer is taking place from high temperature to low
temperature.
The Fourier equation, for steady conduction through a constant area plane wall, can be
written:
Qx ∝ A* (T1 − T2)/t
Writing this relationship as an equality, we have:
Qx = K*A*(T1 − T2)/t

Figure of One-dimensional model of heat conduction in a plane plate

.
Concept of critical thickness
 For cylindrical pipes and spherical object, Heat transfer increasing first, then decreasing.
 Addition of insulation increases conduction resistance, but decreases convection resistance
due to surface area exposed to environment.
 Total thermal resistance decrease resulting in increase in heat loss.
 From outer surface of insulation heat is dissipated to environment by convection.
 As the thickness goes on increasing, area of outer surface increases, which is responsible for
more heat loss thru convection.
INSULATION:-
Insulations are defined as those materials or combinations of materials which retard the flow of
heat energy by performing one or more of the following functions:
1. Conserve energy by reducing heat loss or gain.
2. Control surface temperatures for personnel protection and comfort.
3. Facilitate temperature control of process.
4. Prevent vapour flow and water condensation on cold surfaces.
5. Increase operating efficiency of heating/ventilating/cooling, plumbing, steam, process and
power systems found in commercial and industrial installations.
6. Prevent or reduce damage to equipment from exposure to fire or corrosive atmospheres.
7. Assist mechanical systems in meeting criteria in food and cosmetic plants.
8. Reduce emissions of pollutants to the atmosphere..
THERMAL PROPERTIES OF INSULATION
Thermal properties are the primary consideration in choosing insulations. Refer to the following
Glossary for definitions.
a. Temperature limits: Upper and lower temperatures within which the material must retain all
its properties.

21
b. Thermal conductance "C": The time rate of steady state heat flow through a unit area of a
material or construction induced by a unit temperature difference between the body surfaces.
c. Thermal conductivity "K": The time rate of steady state heat flow through a unit area of a
homogeneous material induced by a unit temperature gradient in a direction perpendicular to that
unit area.
d. Emissivity "E": The emissivity of a material (usually written ε or e) is the relative ability of its
surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to
energy radiated by a black body at the same temperature.
e. Thermal resistance "R": Resistance of a material to the flow of heat.
f. Thermal transmittance "U": The overall conductance of heat flow through an "assembly".
1. System solutions:
1.1 Planning and preparation
The design of a suitable insulation system for technical installations is a major factor for its
economical operation, functionality, security, durability and environmental impact. Additionally,
the installation specific heat losses are specified for the entire life cycle of the plant. Corrections
at a later stage, such as subsequently increasing the thickness of the insulation, for example, may
no longer be possible due to lack of space. Corrections at a later stage may also entail a far
greater investment compared to the original planning.
Continually rising energy costs are also often overlooked factors when dimensioning the
insulation. Insulation thicknesses that are designed to last take energy price increases into
account. They form an important criterion for the economical operation of the installation after
just a few years.
1.1.1. Decision criteria for the design of an insulation system
Selecting a suitable insulation system depends on the following four parameters:
• A. Functional requirements
a. Object dimensions
b. Method of operating the installation
c. Operating temperatures
d. Permissible heat losses or temperature changes of the medium
e. Frost protection
f. Ambient conditions
g. Maintenance and inspection
• B. Safety aspects
a. Personal protection

22
b. Fire protection
c. Explosion prevention
d. Noise reduction within the plant
• C. Economics
a. Economical insulation thickness
b. Pay-back time
• D. Environment
• E. Corrosion prevention
A. Functional requirements
a) Object dimensions
The space requirements of the insulation must be taken into account when the installation is
being designed and planned. Therefore, the insulation thicknesses should be determined in the
early planning stages and the distances between the individual objects should be taken into
account in the piping isometrics. To guarantee systematic installation of the insulation materials
and the cladding without increased expense, observe the minimum distances between the objects
as specified in the following illustrations.
b) Operation of the installation
To select a suitable insulation system, the operating method of the installation must be
considered. A basic distinction is made between continuous and interrupted operation. With
continuous operation, the operating temperatures are constantly above or constantly below the
ambient temperatures. The interrupted operating method, also referred to as intermittent or batch
operation, is characterised by the fact that the installation is switched off between each operating
phase and during that time can assume ambient temperatures. For special applications, so called
dual temperature systems, the operating temperature alternates between above or below the
ambient temperature.
c) Operating temperature
The appropriate insulation material should be resistant to the intended operating/peak
temperatures.
This product property is assessed by the maximum service temperature.
d) Permissible heat losses or temperature changes of the medium

23
With many technical processes, it is essential that media in vessels, columns or tanks do not fall
below a specific lower temperature limit, otherwise chemical processes will not proceed as
intended or the media will set and can no longer be pumped or extracted.
Over-cooling can lead to the precipitation of, for example, sulphuric acid in exhaust and flue gas
streams, which furthers corrosion in the pipes or channels.
With flowing media, it is essential to ensure that the temperature of the medium is still at the
desired level at the end of the pipe. The thermal insulation is designed according to these
requirements. Under extreme conditions (for example, lengthy periods of storage, long transport
routes or extreme temperatures), installing tracing may be necessary, to ensure that the media is
kept within the required temperature limits.
e) Frost protection
Installations that are situated outside are at risk from frost in the winter. In addition to the
undesirable malfunctioning of installations, installations also risk damage caused by the
expansion of frozen water.
Adequate measures – so called frost protection – must be taken to protect the installation from
freezing.
Insulation can reduce heat losses and postpone the moment at which the installation freezes.
Insulation alone, however, cannot indefinitely prevent the installation from freezing. Installing
additional tracing may be necessary between the object and the insulation.
To prevent freezing, the insulation must be designed so that the density of heat flow rate of the
insulated object is less than the heat conducted by the tracing.

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f) Ambient conditions
Select an insulation system that offers long-lasting resistance to the surrounding environment.
• Atmospheric influences: wind, rain
• Mechanical loads such as vibrations or foot traffic
• Corrosive environment (close to the sea, chemicals,)
Prevent the ingress of moisture into the insulation system. Moisture accumulation in insulation
increases thermal conductivity and the risk of corrosion of the insulated installation components.
Cladding must be installed to prevent the ingress of moisture into the system. However, with
installations situated outside with operating temperatures < 120 °C or with installations operating
intermittently, there is a high risk of moisture accumulation. This is caused by moisture
condensing from the ambient air inside the cladding.
For this reason, retain an air space of at least 15 mm between the insulation and the cladding. In
addition, drainage and ventilation holes of minimum 10 mm diameter and at intervals of
maximum 300 mm should be provided on the underside or at the lowest point of the cladding. If
necessary, the insulation and cladding must resist chemical influences that develop within the
environment.
g) Maintenance and inspection
To avoid complicating routine maintenance and inspection work unnecessarily with the
insulation, maintenance-intensive areas must be taken into account, especially when designing
the insulation work.
Removable insulation systems, such as removable coverings and hoods, could be fitted in such
areas, for example. Easily removable covering systems are also recommended for flanges and

25
pipe fittings. These coverings are generally fastened with quick-release clamps, which can be
opened without special tools.
The insulation of fixtures such as flanges or pipe fittings must be interrupted at a sufficient
distance to allow installation or dismounting to be carried out. In this case, take the bolt length at
flange connections into consideration. The connection of the insulation should have an extremity
and any fixtures in the range of the insulation, including the interruption in the installation,
should be insulated with removable coverings.
B. Safety aspects
a) Personal protection
Surface temperatures in excess of 60 °C can lead to skin burns, if the surface is touched.
Therefore, all accessible installation components should be designed to prevent people being
exposed to the risk of injury by burns. The insulation applied to such plant components must
ensure that surface temperatures in excess of
60 °C do not occur during operation. Use the Rockwool
Thermo-technical engineering program “Rock assist” to calculate the required insulation
thickness. All of the operational parameters must be known to achieve a reliable design,
including, for example, the temperature of the object, the ambient temperature, air movement,
surface materials, distance from other objects, etc.
b) Fire protection
The general fire protection requirements imposed on structural installations are usually defined
within the local Building Codes or the specifications of plant owner. Structural installations must

26
be designed, built, modified and maintained to prevent the outbreak of a fire and the spread of
fire and smoke. In the event of a fire, the rescuing of people and animals and effectively
extinguishing the fire must be made possible. During the design of the installation, it is vital to
determine the nature and scope of the fire prevention measures together with the building
supervisory board, the fire brigade, insurance companies and the operator.
As a basic principle, consider the fact that the fire load in a building or technical installation can
be considerably increased by flammable insulation materials. On the other hand, non-flammable
insulation materials such as mineral wool, which has a melting point of
> 1,000 °C, not only have a positive impact on the fire load, but in the event of a fire, also
constitute a certain fire protection for the installation component.
Installation components with tracing, in particular, which use thermal oil as a heat transfer
medium, have an increased risk of catching fire in the event of a leak.
In this case, ensure that the thermal oil cannot penetrate into the insulation material.
c) Explosion prevention
If there is a risk of fire and explosion, the surface temperature of the object and the cladding
must be considerably lower than the ignition temperature of the flammable substance and/or gas
mixtures. This requirement also applies to thermal bridges, such aspipe mounting supports,
supporting structures and spacers etc.
With regard to insulation systems, explosion protection can only be achieved with a doubleskin
covering. A doubleskin covering is a factory made cladding that has been welded or soldered to
make it air proof and diffusion-resistant. In addition special (local) explosion regulations must be
observed.
In many cases (e.g. the German Guideline ZH 1/200) electro statically charged substances, such
as unearthed cladding or non-conductive plastics, are used in explosive areas, “static electricity”
must be earthed.

27
d). Noise protection
The guidelines for noise in the ordinance and workplace are stated in the local regulations and
standards. Generally, the level of the guideline values depends on the nature of the activity, such
as:
• ARAB (Belgium)
• ARBO (Netherlands)
• Code du travail (France)
The sound propagation of installation components can be reduced using insulation systems. The
nature and effect of the sound insulation depend on the frequency and the sound pressure level.
C. Economics
In the industry there are two grades of insulation. The first grade focuses on reducing heat losses
and the prevention of injuries to people operating or working nearby the installations. The
second grade of insulation, the so called “economical insulation thickness” focuses on significant
heat loss reduction and as a result achieving a better return on investment.
a) Economical insulation thickness
Insulation reduces the heat losses from the object.
The thicker the insulation, the greater the heat reduction and consequently, the more energy is
saved.
However, the investment and expenditure, e.g. for depreciation, interest rates and higher
maintenance costs also rise if the insulation thickness is increased.

28
At a certain insulation thickness, the sum of the two cost flows reaches a minimum. This value is
known as the economical insulation thickness. A qualitative curve of a similar costs function is
shown below.
The German VDI guideline 2055 describes in detail various calculation methods used to
determine the economical insulation thickness. The energy costs cannot be based solely on the
current price. Developments over recent years indicate that substantial increases in energy prices
are also anticipated for the future. Increasing energy prices are tending to bring about a shift in
economic insulation thicknesses towards larger thicknesses.
b) Pay-back time
In addition to the economical insulation thickness, another frequently used economical parameter
is the return on investment period (ROI), also referred to as the payback period. This is defined
as the period within which the cost of the insulation is recuperated through savings on heat loss
cost.
In the case of technical insulation systems, the return on investment period is generally very
short, often being much less than one year. Considering only the return on investment period,
however, can be deceptive, as this approach disregards the service life of the installation. With
long-life installations, it is advisable to select higher insulation thicknesses, even if this means
accepting a longer return on investment period.
Throughout the entire service life of the installation however, the increased insulation thickness
results in a significantly higher return on the investment in insulation and achieves a much more
economic operation of the installation.
D. Environmental
The burning of fossil fuels, such as coal, oil or gas, not only depletes the available primary
energy sources, but also, due to the emission of carbon dioxide (CO2) into the atmosphere,
places a burden on the environment. The increasing CO2 concentration in the Earth’s atmosphere
plays a significant part in the global increase in temperature, also referred to as the “greenhouse
effect”. CO2 absorbs the thermal radiation emanating from the earth’s surface and in doing so
reduces the dissipation of heat into space. This will lead to a change in the world’s climate with
as yet inestimable consequences. Reducing CO2 emission can only be achieved through more
efficient management of fossil fuels.
Increasing the insulation thicknesses is essential for the reduction of CO2 emissions. Also refer
to the Technical

29
Letter No. 6 of the German BFA WKSB “High rate of return on environmentally friendly
insulation layer thicknesses”.
Reducing CO2 emissions also has a positive financial benefit for businesses within the context of
the EU emissions trading scheme. The benefits of increase insulation thicknesses in technical
installations are twofold, as the costs for both energy consumption and CO2 emissions are
decreased.
Common Belief:
 Addition of insulation material on surface always leads to lower Heat loss.
 There are instances when addition of insulation material does not reduce Heat loss.
Critical Radius of Insulating Material:
The unit provides find out critical radius of insulation, ratio of thermal conductivity and outside
heat transfer co-efficient. The unit consists of four G. I. pipes provided with plaster of Paris
insulation on outside surface and heater inside, having separate input control. Input to heaters is
measured by common voltmeter& ammeter

30
Figure of insulated
CHAPTER 2
Design objective:
The insulation system designer must be aware of the objectives of the installation and the amount
and type of equipment planned to achieve these objectives. In some cases, as with steam heating,
proper insulation planning can reduce the required capacity of the generating system. In the case
of fruit and vegetable or refrigerated meat storage, temperature maintenance and condensation
control objectives will supersede economic thickness design. Appearance and hygiene factors
can also affect the choice of finishes in exposed areas and/or areas where food is being prepared
or stored.
Condensation control on ducts, chillers, roof drains and cold piping is a basic function of
insulation in commercial buildings. Design objectives here are to choose materials and
application methods which will achieve the best vapour retarder seal possible, and to calculate
the thickness of insulation necessary to prevent condensation.

31
Insulation chosen for personnel protection and/or fire protection must be able to withstand high
temperatures without contributing to a possible fire hazard. Engine exhausts which can reach
temperatures of 455°C to 675°C should be insulated sufficiently to reduce surface temperatures
exposed to personnel or flammable materials to under 60°C. Kitchen exhaust ducts which are
subjected to flammable grease accumulation fall within the same design criteria.
Analysis:-
As mentioned before, when it is desirable to decrease heat gain or heat loss, the critical radius
only serves as a necessary condition, but it is not sufficient. To address design issues of such
thermal systems, the crossover radius is utilized. The crossover radius is defined as a radius
greater than the critical radius such that the heat transfer with the corresponding amount of
insulating material is equal to that of the bare thermal system. Cylindrical systems are analysed
first followed by the spherical systems.
Cylindrical system:-
It is known that for any radial system there exists an optimal insulation thickness. This can be
proved by the fact that there are competing effects when insulation is increased. The first effect is
that the conduction resistance increases when adding insulation. The competing effect is that as
insulation is added, the total surface area of the system increases, causing the convection
resistance to decrease. Thus there must be an optimal insulation thickness that minimizes the
overall heat loss. Calculation of critical radius of insulating material on circular solid of
conducting material is followed. Consider a cylindrical pipe of outer radius r1which is heated
and whose outer surface temperature T1 is maintained constant. The pipe is now insulated with a
material whose thermal conductivity is k and outer radius is r2. Heat is lost from the pipe to the
surrounding medium by combined effect of conduction and convection. The rate of heat transfer
from the insulated pipe to the surrounding air is measured by using temperature sensors like
thermocouple. The value of r2 at which heat transfer rate reach maximum is determined.
Performing the differentiation and solving for r2 yields the critical radius of insulation for a
circular body. The critical radius of insulation is given by the following equation Rcr =

32
(k/h).Above this critical radius, the heat flux decreases and below it, the heat flux increases as
the fig.1below illustrates
The heat flow per unit length, Q is given by.
Q =.2πl (t2-t1)/ (ln(r2/r1))
A problem of interest is choosing the thickness of insulation to minimize the heat loss for a fixed
temperature difference T1 - T∞ between the inside of the pipe and the flowing fluid far away
from the pipe. (T1 - T∞ is the driving temperature distribution for the pipe). To understand the
behavior of the heat transfer we examine the denominator in Equation (3.23) as r2 varies. The
thickness of insulation that gives maximum heat transfer is given by
(r2) maximum heat transfer =
k/h.

33
Fig.1 critical Radius of Insulating Material.

34
The F figure: 2 of variation of HT w.r.to critical thickness of insulation
EXPERIMENTATION SETUP FOR CYLENDER

35
Fig.2.Setup Diagram.
Set up diagram( fig.2) consist of Frame, Thermocouple, Temperature Indicator, Voltmeter,
Ammeter, Copper Rod, Resistive Heater, Main Switch, Electric Conductor Wire, Asbestos
Insulation .Frame of mild steel by length, Height,Width,is manufactured. Frame is used to
supportother equipment/Control Panels (Thermocouple, Temperature Indicator, Voltmeter,
Ammeter, Copper Rod, Resistive Heater, Main Switch.) Supporting Frame is placed on the main
frame to the support of Insulating Copper Rod as well as Resistive Heater is placed inside of
copper Rod as shown in fig. 2.Resistive heater is used for heating of copper rod. Heater is direct
connecting to the Dimmer stat. Dimmer stat is used to increase or decrease Voltage, or adjust the
voltage what is required for steady state condition. If voltage increases then more time consume
for coming steady state condition or its decreases then it will come yearly in steady state
condition. No. of thermocouples are placed on surface of Copper Rod, because thermocouples
sense the surface temperature of copper rod . Asbestos insulation is wounded outside surface of
copper rod. Then thermocouples are placed outside surface of insulation. K typethermocouples
are used to measure temperature because frequency of k type thermocouples is more high.
Temperature Indicator is used to indicate temperature at every position of thermocouple.
2.2. Spherical system

36
As before, consider a layer of insulation all around a sphere. For sake of simplicity, let the inner
temperature of the insulation be fixed at t1, and the outer surface be exposed to a convection
environment at t1. It should be pointed out that for situations where there are internal resistances
and sphere conduction resistance, the analysis for crossover radius will still yield identical results
since these internal resistances are unaffected by the insulation. Now if we assume a constant
convective heat transfer coefficient, h, and neglect any contact resistance and radiation, using
identical approach as before we can in obtain the quadratic algebraic equation for crossover.
An incompressible viscous fluid flow with heat transfer over a spherical object inside a pipe is
considered. The flow is made three-dimensional by an eccentric positioning of the sphere inside
the pipe. The governing equations are solved by a numerical method which uses a finite volume
formulation in a generalized body fitted coordinate system. An overset (Chimera) grid scheme is
used to resolve the two geometries of the pipe and sphere. The results are compared to those of
an external flow over a sphere, and the code is validated using such results in the intermediate
Reynolds number range. The blockage effects are analyzed through evaluation of lift, drag, and
heat transfer rate over the sphere. Also the change in the shear stress pattern is examined through
evaluation of the local friction factor on a pipe wall and sphere surface.
Equation of heat flow as:
Q = 4 π r 1r 2* k *(t 1−t 2)÷r 1−r 2
Critical radius:
Rc = 2h/k…………………………for spherical object
Where,
h is convective heat coefficient of atmosphere in (W/ m2
K ).
k is conductivity of insulating material in (W/m K).
CHAPTER 3
Experimental setup:

37
Plaster of Paris:
Plaster of Paris is used in making the composite material, which can be used as thermal insulator
and decorative interiors. The false ceiling, roofing for decoration is mostly done by POP, for
installation of Air conditioning it is one the requirement to have a false ceiling. The POP is acts
like a matrix and a reinforcing fibre may be used to make POP Slabs.It is used as a binding
material.
Thermal conductivity:-
In physics, thermal conductivity, k, is the property of a material that indicates its ability to
conduct heat. It appears primarily in Fourier's Law for heat conduction. Thermal conductivity is
measured in watts per Kelvin per meter (W·K−1·m−1). Multiplied by a temperature difference
(in Kelvin’s, K) and an area (in square meters, m2), and divided by a thickness (in meters, m) the
thermal conductivity predicts the power loss (in watts, W) through a piece of material. The
reciprocal of thermal conductivity is thermal resistively
Thermal conductivity of plaster of Paris is: K = 0.397 W/m K.
Heating Element Nichrome wire:

38
Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a
resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A
common alloy is 80% nickel and 20% chromium, by mass, but there are many others to
accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a
high melting point of about 1400 °C (2552 °F). Due to its relatively high electrical resistivity and
resistance to oxidation at high temperatures, it is widely used in electric heating elements, such
as in hair dryers, electric ovens, soldering iron, toasters, and even electronic cigarettes.
Typically, Nichrome is wound in coils to a certain electrical resistance, and current is passed
through to produce heat.
Uses
Nichrome is used in the explosives and fireworks industry as a bridge wire in electric ignition
systems, such as electric matches and model rocket igniters.
Industrial and hobby hot wire foam cutters use nichrome wire.
Nichrome wire is commonly used in ceramics as an internal support structure to help some
elements of clay sculptures hold their shape while they are still soft. Nichrome wire is used
because of its ability to withstand the high temperatures that occur when clay work is fired in a
kiln.
Nichrome wire can be used as an alternative to platinum wire for flame testing by colouring the
non-luminous part of a flame to detect cations such as sodium, potassium, copper, calcium etc.
The alloy tends to be expensive due to its high nickel content. Distributor pricing is typically
indexed to commodity market prices for nickel.
Other areas of usage include motorcycle silencers, in certain areas in the microbiological lab
apparatus, and as the heating element of plastic extruders by the Riprap 3D printing community.
For heating, resistance wire must be stable in air when hot. Nichrome wire forms a protective
layer of chromium oxide.

39
Properties
The properties of nichrome vary depending on its alloy. Figures given are representative of
typical material and are accurate to expressed significant figures. Any variations are due to
different percentages of nickel or chromium.
Material property
Value Units
Modulus of elasticity 2.2 × 1011
Pa
Specific gravity 8.4
Dimensionless

40
Density 8400
kg/m3
Melting point 1400
°C
Electrical resistivity at room temperature 1.0 × 10−6 to 1.5 × 10−6
Ωm
Specific heat 450
Jkg−1°C−1
Thermal conductivity 11.3
Wm−1°C−1
Thermal expansion 14 × 10−6 °
C−1
Table of nichrome coil property
Nichrome composition:-
NiCrA
Chemical Composition: 80% Ni, 20% Cr
Approx. Melting Point: 1400 degree C
NiCrC
Chemical Composition: 61% Ni, 15% Cr, bal. Fe
Approx. Melting Point: 1350 degree C

41
THERMOCOUPLE?
In 1821, Thomas Seebeck discovered if metals of two different materials were joined at both
ends and one end was at a different temperature than the other, a current was created. This
phenomenon is known as the Seebeck effect and is the basis for all thermocouples.
A thermocouple is a type of temperature sensor, which is made by joining two dissimilar metals
at one end. The joined end is referred to as the HOT JUNCTION. The other end of these
dissimilar metals is referred to as the COLD END or COLD JUNCTION. The cold junction is
actually formed at the last point of thermocouple material
Certain combinations of metals must be used to make up the thermocouple pairs. If there is a
difference in temperature between the hot junction and cold junction, a small voltage is created.
This voltage is referred to as an EMF (electro-motive force) and can be measured and in turn
used to indicate temperature.
The voltage created by a thermocouple is extremely small and is measured in terms of millivolts
(one millivolt is equal to one thousandth of a volt). In fact, the human body creates a larger
millivolt signal than a thermocouple.
To establish a means to measure temperature with thermocouples, a standard scale of millivolt
outputs was established. This scale was established using 32 deg. F (0°C) as the standard cold
junction temperature (32 deg. F (0°C) = 0 millivolts output

43
Types of thermocouple:
Type Materials* Typical
Range °C
T 1, 2 Copper (Cu) vs Constantan -270 to400
J 1, 3 Iron (Fe) vs Constantan -210
to1200
K Chromel vs Alumel -270 to
1370
E Chromel vs Constantan -270 to
1000
S (Pt-10%Rh) vs Pt -50 to 1768
B (Pt-13% Rh) vs (Pt-6% Rh) 0 to 1820
R (Pt-13%Rh) vs Pt -50 to 1768
Table of Standard Thermocouple Types
2.6.4. Surface Temperature Measurement
Although thermocouple assemblies are primarily tip sensing devices, the use of protection
tubes (sheaths) renders surface sensing impractical. Physically, the probe does not lend itself
to surface presentation and stem conduction would cause reading errors. If a thermocouple is
to be used reliably for surface sensing, it must be in either exposed, welded junction form

44
with very small thermal mass or be housed in a construction which permits true surface
contact whilst attaching to the surface. Locating a thermocouple on a surface can be achieved
in various ways including the use of an adhesive patch, a washer and stud, a magnet for
ferrous metals and pipe clips. Examples of surface sensing thermocouples are shown below:
Wrong scale might be used or might be read incorrectly.
Fig 13: Thermocouples for Surface Temperature Sensing

45
Voltmeter:
Avoltmeter finds its importance wherever voltage is to be measured. Here we present an
easyto- build and accurate digital voltmeter that has been designed as a panel meter and can
be used in DC power supplies panels or where it is necessary to have an accurate indication
of the voltage. A voltmeter is an instrument used for measuring electrical potential difference
between two points in an electric circuit. Analog voltmeters move a pointer across a scale in
proportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage
by use of ananalog to digital converter.
Voltmeters are made in a wide range of styles. Instruments permanently mounted in a panel
are used to monitor generators or other fixed apparatus. Portable instruments, usually
equipped to also measure current and resistance in the form of a multimeter, are standard test
instruments used in electrical and electronics work. Any measurement that can be converted
to a voltage can be displayed on a meter that is suitably calibrated; for example, pressure,
temperature, flow or level in a chemical process plant.
Two type of voltmeter
Digital type
Fig 1 of digital type voltmeter

46
Anolag taype
Fig of analoge type voltmeter
AMMETER
An ammeter is a device designed to accurately measure and display electrical current in a
readable form, which could be a moving coil meter, a LED bar graph display or a digital
panel meter. The basic unit of electrical current is amps. When designing an ammeter,
external resistors, or shunt resistors (or sometimes known as current resistors), are connected
in parallel with the moving coil meter or digital panel meter to extend or convert the range.
This arrangement divides the current being measured so the majority flows through the shunt
resistor and a small portion goes to the meter. Shunt resistors are calibrated: for example, the
Jay car QP-5416 has a voltage drop of 200mV across it when the current flowing through it is
200A. This calibrated information is stamped on the side of the shunt. An ammeter is a
measuring instrument used to measure the electric current in a circuit. Electric currents are
measured in amperes (A), hence the name. Instruments used to measure smaller currents, in
the mill ampere or microampere range, are designated as mill ammeters or micro ammeters.
The majority of ammeters are either connected in series with the circuit carrying the current
to be measured (for small fractional amperes), or have their shunt resistors connected
similarly in series. In either case, the current passes through the meter or (mostly) through its
shunt. They must not be connected to a source of voltage.

47
DIGITAL AMMETER:
Digital ammeter designs use a shunt resistor to produce a calibrated voltage proportional to
the current flowing. This voltage is then measured by a digital voltmeter, through use of an
analog to digital converter (ADC); the digital display is calibrated to display the current
through the shunt.
Fig of digital type ammeter
ANALOG TYPE AMMETER

48
Fig of analog type ammeter
Toggle switch:
Specifications:
Contact rating - Dependent upon content material.
Mechanical life - 40,000 make and break cycles.
Maximum contact resistance - 10mΩ.
Initial voltage - 2 to 4V dc.
Current - 10mA for both silver and gold plated contacts.
Minimum Insulation resistance - 1,000MΩ.
Dielectric strength - 1,000Vrms at sea level.
Operating temperature - 30°C to 85°C.
Materials:
Case : Diallyl phthalate (DAP) (UL94v-0).
Actuator : Brass, chrome plated.
Bushing : Brass, nickel plated.
Housing Stainless steel.
Switch support : Brass, tin plated.

49
Terminal/contact : Silver or gold plated.
Fig: of a toggle switch
DIMMERSTAT:-
Dimmerstat is the device with ac input an ac output. it consist of a variable transformer inside
it so as to vary the output. Dimmerstat' is registered trade mark for AE make continuously
variable voltage auto-transformer. It is the most effective device for stepless, breakless &
continuous control of AC voltage & therefore for various parameters, dependent on AC
voltage.
The basic Dimmerstat is meant for operation from a nominal input voltage of 240V 1ph AC
& can give output voltage anywhere between 0 to 240V or 0 to 270V AC by simple
transformer action. Three such Dimmerstats connected electrically in star and mechanically
in tandem, become suitable for operation from a nominal input voltage of 415V 3Ph AC and
can give output anywhere between 0 to 415V or 0 to 470V.

50
Fig.of dimmerstat
3.5 Temperature Indicator:
Temperature Indicator ( 12 channels), used the advanced SMT technology, to be designed
high quality and performance, high accuracy, universal use, to be aimed to measure and
display multi-points value, testing and inspecting circuitry, display the processes in various
industry application for temperature, humidity, pressure, level, flow, weight etc.
We can get the temperatures of all the thermocouples with the help of this digital temperature
indicator by simply just pressing the button on the indicator itself

51
Fig.24 8 channel Digital temperature indicator
CHAPTER 4
4.5 DATA REQUIRED FOR INDUSTRIAL INSULATION SYSTEM
DESIGN:
4.5.1 NATURE OF THE PROCESS
The possibility of spillage, leaks and accidental contamination of process chemicals and
products is always present in industrial installations. Insulations should be chosen which do
not react to the chemicals contained in the vessels or piping to which they are applied.

52
Such a reaction may lower the ignition temperature of the process chemical or insulation
material, contributing to fire hazard conditions.
Special care should be taken to use non-absorbent insulations in the presence of combustible
or toxic liquid. Spontaneous combustion of a combustible liquid absorbed over the large
surface area of insulation may occur as it oxidizes. Absorbent insulation may contribute
significantly to an accidental fire by storing up the spilled or leaked combustible materials.
Stainless steel is the most appropriate of the metal jacketing materials, having high resistance
to corrosives and bacterial growth as well as high mechanical strength. High cost of stainless
steel usually limits its use to fire protection and corrosive environments. Aluminium may
erode in wash down areas or where strong cleaning chemicals are used.
The use of weather and vapour retarder coatings, reinforced with glass cloth or mesh,
provides a mechanically strong and sanitary finish for equipment and other irregular surfaces.
Many are also resistant to chemicals.
3.5.2 SPECIFIC TEMPERATURE PARAMETERS OF PIPING AND EQUIPMENT
In addition to the reduction of energy usage, industrial insulation systems must maintain
controlled temperatures required for process materials being transported from one point in a
facility to another.
Temperature control may be continuous, intermittent, cyclic or rapidly changed due to
weather conditions or the necessity of steam cleaning and wash down periods.
An insulation of high thermal diffusivity, low specific heat and low density is desirable in
installations which require rapid heat-up or cool-off of insulated surfaces. A process changing
from hot to cold every few minutes requires an insulation that has the ability to change
temperature quickly and has very low mass to retain heat.
The temperature of an insulation's outer surface must be considered where insulation is used
for personnel protection or to protect the jacket or mastics or where excessive surface
temperatures might cause ignition of fumes or gases. On low temperature installations,
surface temperatures must be above dew point to prevent condensation and drip. The
emissivity property of insulation finishes is significant in these cases. High emissivity is
recommended on finishes used for personnel protection treatments.
On installations where temperatures must be maintained at specific levels, it must be decided
in the design phase whether added insulation thickness or heat tracing or both would provide
the most efficient service. This decision is based on data other than the conventional
economic thickness considerations.
Extreme temperature surfaces in industrial process and power facilities may require the use of
materials and application methods which can absorb expansion, contraction and vibration

53
movement. Stainless steel banding or expansion bands are recommended for applications
with extreme expansion movement or on large diameter surfaces. Because most high
temperature insulations shrink while the metal surface expands, methods such as double layer
- staggered joint construction, the design and placement of cushioned expansion joints and/or
the use of high rib lath between insulation and metal surfaces may be employed to protect the
insulation seal.
Awareness of the nature of the process, its components, the relative temperatures of piping
and equipment and the general location of such equipment and substances, aids the specified
in determining areas where excess heat or chemicals may create fire hazards or personnel
hazards.
3.5.3 METAL SURFACES RECEIVING INSULATION TREATMENT
A selected insulation should not be chemically reactive to the metal over which it is applied.
Basically, insulation installed on steel should be neutral or slightly alkaline. That installed on
aluminium should be neutral or slightly acidic.
External stress corrosion, cracking of austenitic stainless steel may result from the presence
of chloride ions on its surface. Insulation containing chlorides or located in a salt laden or
chloride contaminated atmosphere must not be in direct contact with unprotected stainless
steel surfaces.
In the case of stainless steel jacketing, factory-applied moisture retarders on the inner surface
may be sufficient protection. Virtually all stress corrosion cracking is caused by chlorides
introduced from the atmosphere or from chemical fumes and not from the insulations
themselves.
3.5.4 OPERATING DATA
The location of instruments and maintenance areas where personnel will be present is
significant when specifying treatments for personnel protection and materials abuse
protection from foot traffic, excessive handling and operational machinery. Rigid insulation
materials and jacketing are recommended in these areas. High pressure wash down areas
require resistance to water and detergents as well as high mechanical strength.
3.5.5 FUTURE ACCESS AND MAINTENANCE REQUIREMENTS
Leaks are most likely to occur at valves, fittings and flanges. Low temperature insulation can
be protected from leaks by sealing off adjacent insulation with vapour-retarder mastics.
Removable fitting covers may be specified at predictable maintenance areas, while special
leak detection mechanisms may be installed at other locations. However, on hot applications

54
a rigid inspection and replacement program is the best prevention of large scale insulation
destruction due to leakage.
Turbines, which require easy access for inspection and maintenance, can be insulated with
removable insulation blankets fabricated from stainless steel mesh or high temperature fabric
filled with fibrous insulation. These are attached to turbine surfaces by means of metal
eyelets built into the blankets around the edges.
The floor level of large tanks can be protected from spilled chemical or water from wash
downs by using a non-absorbent insulation along the bottom skirt or support, or by sealing
with caulking.
3.5.6 ATMOSPHERIC CONDITIONS
The atmosphere surrounding industrial piping and equipment presents additional problems in
the selection of finishes and jacketing. Of particular concern is the presence of chemicals or
humidity which act to corrode metal finishes.
Because of its excellent weather-barrier and mechanical properties, metal jacketing is widely
used on industrial installations. The metals most resistant to corrosive chemicals and
humidity are stainless steel and coated electro-galvanized steel. Coated aluminium can be
used to combat specific conditions by selection of the exact coating required. However, the
coatings are not always abrasive resistant, leaving the aluminium open to attack at fastener
openings, cuts, etc. Aluminium is weather resistant but does not always hold up in a wash
down area or where strong cleaning chemicals are used. Factory-applied moisture-retarders
are recommended on aluminium jacketing to prevent galvanic corrosion.
The coverings considered most resistant to corrosives and abrasive chemicals are the plastic
types.
Unless protected, some PVC type coverings may break down when subjected to the effects of
ozone, infra-red and ultra-violet rays. Protective paints are available for PVC coverings not
manufactured for outdoor use. Weather barrier coatings offer good protection from weather
as well as from the chemical attack of acids, alkali, solvents and salts, either airborne or as a
result of intermittent spillage. Glass cloth and other fabric membranes are generally used as
reinforcements and add mechanical strength to the installation.
Maximum protection from chemical attack on cold and dual temperature service is achieved
through the use of vapour retarder coatings. They, too, are applied with reinforcing fabric.
Stainless steel jackets and bands are recommended in areas which require superior fire
resistance.
Stainless steel is recommended over the use of aluminium due to the latter's lower melting
point.

55
Some weather and vapour retarder mastics also add fire retardant properties to an insulation
system.
3.5.7 CLEARANCES
Because of the complexity of process piping and the added thickness required to control heat
loss or gain, clearances often become so minimal that it can be necessary to insulate piping
together in groups. This is also true in marine work.
3.5.8 SCHEDULING AND MATERIALS STORAGE
Precise industrial installation schedules and good application practice often dictate that
insulation be finished as soon as possible after roughing-in. The materials chosen must have
the necessary strength to resist any excessive amount of handling and moving at the
installations site. Materials which are moisture absorbent must also be protected from water
while being stored at the site. Storage areas should be clearly indicated for the insulation
contractor in project specifications, and should be noted as covered or open.
3.5.9 SPECIFICATIONS
Contract drawings should indicate the extent and general arrangements of the yard and the
process piping to receive insulation treatment. The size of piping and equipment, linen
origination and termination, elevations, support locations, and orientation of nozzles, fittings
and valves should also be indicated and properly dimensioned.
3.5.10 QUALITY OF MATERIALS
Insulation and associated materials should be specified and ordered to meet appropriate codes
and standards. Manufacturers' data sheet and test reports should be consulted in the selection
process to determine conformity.
CHAPTER 5
PRODUCTS:
4.1 PRODUCTS
The following listed manufacturers’ products have been accepted by TIAC as suitable for
application based on technical data available from the various manufacturers. The
terminology used in this products listing is consistent with that used within the Application
and Finishes parts of these standards. The following manufacturer lists contain acceptable
materials in regular supply in most areas (see Provincial addenda). Unless specifically noted
otherwise in the project specifications, the Contractor has the option of which one of the
listed manufacturers’ products to use on a project for the various applications and finishes
specified. The specifier should verify these specifications before using.

56
A. PREFORMED PIPE INSULATION
1. Mineral Fiber for Low and Medium Temperature (with or without integral jacket)
- Knauf Insulation
- Manson Insulation Inc.
- Owens Corning Canada Inc.
- Fibrex Insulations Inc.
- Roxul Inc.
- Johns Manville
- Industrial Insulation Group IIG-LLC
2. Calcium Silicate for High Temperature
3. Mineral Fiber for High Temperature
- Roxul Inc.
4. Perlite for High Temperature
- Temperlite
- Howred Corp.
5. Cellular Glass
- Pittsburgh Corning Corp.
- Cell-U-Foam Corporation
6. Flexible Foam Elastomeric
- Armstrong World Industries
- Halstead Corp.
7. Closed Cell Polyisocyanurate
- Dow Chemical Canada Inc.
8. Phenolic
- Belform Insulation Ltd.
B. UNDERGROUND INSULATION (GRANULAR TYPE)
- Dri-Therm
- Gilsulate
C. DUCT AND PLENUM INSULATION
1. Rigid Mineral Fiber Board for Low and Medium Temperature (with or without vapour
retarder)

57
- Knauf Insulation
- Ottawa Fibre Inc.
- Roxul Inc.
- Johns Manville
2. Flexible Mineral Fiber Blanket for Low and Medium Temperature (with or without vapour
retarder)
- Knauf Insulation
- Ottawa Fibre Inc.
- Roxul Inc.
- Johns Manville
3. Calcium Silicate for High Temperature
4. Mineral Fiber for High Temperature
- Fibrex Insulations Inc...
- Industrial Insulation Group IIG-LLC.
- Roxul Inc.
5. Perlite for High Temperature
- Temperlite
- Howred Corp.
6. Cellular Glass- Pittsburgh Corning Corp.- Cell-U-Foam Corporation
7. Flexible Elastomeric Foam- Armstrong World Industries- Halstead Corp.
8. Closed Cell Polyisocyanurate- Dow Chemical Canada Inc.
9. Phenolic- Belform Insulations Ltd.
D. MINERAL FIBER DUCT LINER FOR INTERNAL APPLICATIONS
- Knauf Insulation

58
E. FINISH JACKETS
1. Multi-Purpose
- Alpha and Associates
- Claremont
- Lamotite
- Compac Corp.
2. Treated Jacket
- Alpha and Associates
- Claremont
- Fattal Thermocanvas
3. PVC Jacket and Fitting Covers
- Ceel-Co
- Belform Insulation Ltd.
- Proto Corp.
- Sure-Fit System
- Speedline
- Thermo-Cover Inc.
- Zeston
4. Aluminum and Stainless Steel Jacketing and Fitting Covers
- Aluminum materials must be furnished from aluminum with alloys conforming to
ASTM B-209 designation.
- Stainless Steel materials must be type 304 or Type 316 stainless steel conforming to ASTM
A-240.
5. Vapour Retarder facing adhesive; Insulation and Fabric Coatings; Fitting Mastic;
Fabric Adhesive; Mastic Coating
- Bakor
- Specialty Construction Brands Inc. (Fosters/Childers)
- Epolux
- Nacan
F. ACCESSORIES
1. Tapes
- Avery Dennison
- Compac Corp.
- Ideal Tape

59
- MACtac Canada Ltd.
- Venture Tape Corp.
-Dow Chemical Canada Inc.
2. Weld Pins, Studs and Clips
- AGM
- Continental Studwelding
- Midwest Fastners Inc.
3. Insulating Cements
- PK Insulation
4. Vapour Retarder Film
- Dow Chemical Canada Inc.
5. Removable/Reusable Covers Other Companies
- Albrico Services (1982) Ltd. to be listed on
- - Connelly Insulation Services
- Crossby Insulation Inc.
- Dewar Insulations Ltd.
- Ener Guard Protective Coverings Inc.
- Firwin Corporation - Guildfords Ltd.
- Heat Saver Covers Ltd. - Inscan Contractors Ltd.
- Isolation Generales A.P.T. Inc. - Interprovincial Insulation Inc.
- Isolation Industrielle Quebec - Knauf Fiber Glass
- LGF Mechanical Insulations - Pro-Tec-T-Kotes
- RRC Insulation - Sarnia Insulation Supply (1985) Ltd.
- Scotia Insulation Sales Limited - Thermo-Cover Inc.
- Thermal Energy Conservation Inc. - Thermal Systems
EXPERIMENT
AIM: To determine critical thickness of insulation on sphere conductivity.
ASSUMPTIONS:
1) All air gaps are neglected.
2) Heat is assumed to be uniformly distributed
3) Convection between SS sphere and the heater is neglected.
4) Radiations losses are neglected.

60
5) Clamps used for holding the insulated rod do not absorb any heat during the process and
hence aren’t considered in calculations.
Equipment’s:-
1).Watt meter --Ammeter & Voltmeter separately.
2).Thermocouple -- pt – 600°C, 20% full scale accuracy.
3).Electric dimmer start --1.5 KW.
4).Inner sphere diameter --127mm.
5).fist test piece Outer sphere diameter --200mm.
6).second test piece outer daimeter—180mm.
Ammeter rating is 0 to to 5 Amp. & that of voltmeter is 300V.
Experimental Set Up:-
. Heater is provided inside inner sphere for uniform heating of sphere. Six thermocouples
(three on each sphere) are provided to measure temperature difference across powder
specimen. Provision has been made to measure the heat input.
Procedure:
1). Connect the supply plug to the socket.
2). Check the all the dimmers tats are at zero position.
3) .Initially all the selector switch should be in upward direction.
4). Switch ‘ON’ the main switch and the corresponding heater switch .Operate the
corresponding dimmer state one by one and adjust the input to the heaters such that all the
heater surface temperature come to be the same.
5). fist observation is taken after 40 minutes to ensure steady state.
6). Readings of all 4 thermocouples are taken after steady state &then dimmer start is a
jousted to change heat input & another set of readings taken after 15 minutes
OBSERVATION TABLE:-
Sr.No Test piece Input
T1(°C) T2(°C)
Voltage current
1 TP1 0.5 A 86 58

61
2 TP2 0.5 A
Where,
T1 = inner surface temperature in c
T2 = outer surface temperature in c
Sample Calculations:-
1. For test piece TP1
Given.
K=Thermal conductivity of insulation (0.46 W/m.K).
Ro = 0.127 m.
Ri = 0.142 m.
Q = V.I = 100V *0.5A =50 Watts
Am = 4 π RiRo = 4 π * 0.05 * 0.1 = 0.06283 m2
R0-Ri = 0.1 - 0.05 = 0.05m
Ti – T0 = 91.5 – 29.67 = 61.83c = 61.8
2. For test piece TP2
Result :- Critical thickness of insulation is found to be……… mm.
Precautions:-
i) Dimmer start volt should not be exceeded
ii) Sphere should not be dislocated by holding pipe.
iii) Operate all the switch and knob gently.
iv) Use only one selector switch at a time.
v) Check ‘earthing’is connected to the unit.
vi) Before putting ‘ON’ the main switch see the all the dimmer stats are at
zero position and all the selector switch are in down ward direction.
Discussion:

62
 Result we obtain is based on presumption that only one dimensional heat conduction
occurs which may not be true in real practice as heat may flow in all direction.
 Determination of arrival of steady state is difficult.
INDUSTRIAL INSULATION:
Conditions exist in industrial installations such as power plants, chemical plants, petroleum
refineries, steel, pulp and paper mills, meat packing plants, food, soap, and cosmetic process
plants, marine work, etc., which require that the insulation systems designer be involved in
the project during the design phase. Depending upon the industrial process of function of the
installation, these conditions include:
1. Stringent control of extreme temperature parameters.
2. Corrosive atmospheres resulting from the presence of process chemicals or the location of
equipment and piping outdoors.
3. Increased fire hazard caused by high temperatures and the presence of volatile substances.
4. Presence of operating personnel. (Personnel protection)
5. Sanitary and contamination requirements for food, meat packing, soap, cosmetic, dairy and
brewery processes.
6. Additional mechanical abuse to insulations from excessive handling, foot traffic on vessel
tops and lines, and the added movement of expansion, contraction and vibration.
7. Necessity for easy removal of insulation for predictable maintenance areas.
8. Critical clearance and space limitations coupled with the need for greater thickness of
insulations.
9. Complex construction and installation schedules.
10. Radiation hazards in nuclear facilities.
11. To determine the insulation thickness for pipe line in process industry.
12. To determine the steam pipe insulation thickness in power plant.
13. To determine the furnace wall thickness.
14. Work accessibility requiring scaffolding, cranes, etc.
Pertinent data concerning the installation design objectives, the materials being processed or
used, applicable government regulations or codes, operating data and temperature parameters
must be determined far enough in advance of final specification preparation to insure the
design of a properly functioning insulation system.

63
IV. CONCLUSIONS
Because of the nonlinear nature of the problem, the solution for the critical radius has been
obtained by numerical means, however, an explicit analytical solution has been obtained for
three special cases.
The critical radius of the coating is found for a spherical particle which is subjected to a
radiative and convective heat transfer environment.
It is found that the critical radius of the coating increases when either convection or radiation
decreases. Therefore, the existence of the critical radius depends on both the convection and
radiation parameters. The critical coating radius increases for decreasing convection and
radiation heat transfer. Thus, it becomes feasible to use a critical coating radius for heat
transfer enhancement only for high convection or radiation heat transfer environments.
1. With the help of this apparatus we can determine the critical radius of any insulating
material by changing insulating material.

64
2. The same set up can be modified to determine the critical radius for different geometries.
(eg. sphere)
3. By calculating heat transfer through bare radius system by considering all losses, we can
calculate cross over radius by adding more and more insulating material beyond critical
thickness.
4. Receive good critical point.
5. Noiseless and easy working operation.
6. Understood the concept of critical thickness of insulation and graphically represented the
variation of heat loss against insulation thickness.
7. Apply the concept of critical thickness of insulation to decide appropriate thickness for
practical applications.
8. Developed an expression for critical thickness if insulation in case of cylinder and solved
numerical problem based on expression for critical thickness if insulation.
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65
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