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					Technological Studies
   Case Study Report
        (Higher)


                       6564
Spring 2000
                         HIGHER STILL




              Technological
                   Studies
                Case Study Report


                             Higher




Support Materials
CONTENTS

A new gasket material

Table of contents

Title page

Table of Contents

Background

Analysis and Description

Social, Economic & Environmental Effects

Conclusion

Acknowledgements




DET: Technological Studies: Case Study (Higher)   1
DET: Technological Studies: Case Study (Higher)   2
TECHNOLOGICAL STUDIES (HIGHER) CASE REPORT

Notes for staff and students
This exemplar Case Study Report is written as though produced by a candidate who at
an appropriate time through the course was allocated time to carry out the task. It is
recommended that the Case Study Report should commence well into the course, and
that 20 hours be allocated, but this is the discretion of the centre. There should be a
balance between class work and homework.

The candidate was given access to research materials in the form of magazines,
brochures, books, CD-ROMs, videos and so on. In the course of this he came across
an article in the December 1998 issue of Engineering Technology regarding the
development of a gasket material to be used as a replacement for asbestos based
gaskets. Through his reading he had become aware of the danger to health attributed
to the use of asbestos in industry, and his interest was aroused.

To follow up the article he used Microsoft Encarta to obtain information about the
distribution of asbestos in the world, and details of its extraction and the processes
involved. He followed this up with further reading. Using the Internet he visited the
web sites of various firms and downloaded further information. He noted telephone
numbers and addresses, as well as e-mail addresses in case of need.

It was now time to put the material into order and plan the layout of his report. A
rough plan was prepared for which he sought confirmation from his teacher that he
was on the right track. Time was allowed to build up skill with drawing packages and
word processing programmes on a PC. The teacher advised him of the two Outcomes
and relevant Performance Criteria. Using SCCC publications and textbooks in the
department the candidate revised the Systems Approach and the correct graphical
representation.

The Report was then prepared using word processor and desktop publishing packages,
and it was presented to the teacher. Teacher assessed each outcome and recorded the
result on the Case Study Report – Record of Assessment. A tick was used to
signify achievement of each of the Performance Criteria, a cross, indicated a failure to
meet any of the Performance Criteria. At the same time he completed Case Study
Report – Feedback to Candidates.

This Exemplar Report contains just over 2000 words, this being the target number.
However there is no penalty associated with the number of words.

In making an assessment the teacher should recognise that the nature of the product or
process being investigated can affect the strength of reporting of the various aspects.
For instance it is easier to produce system and sub-system diagrams for an electronic
product or process than for a frame structure or mechanical process. Similarly the
social, economic and environmental effects of a small local factory will be
insignificant compared with a multi-national company with factories and outlets
worldwide.




DET: Technological Studies: Case Study (Higher)                                          3
The teacher adjudged that the report justified a tick for each heading, that is success in
each PC. He added suitable comments and advice where appropriate. Had there been
a cross, the candidate would have been informed of the opportunity for a retest, the
feedback sheet indicating the areas in doubt.

As well as the Report, the candidate filed all the research material for future reference.




DET: Technological Studies: Case Study (Higher)                                         4
A NEW GASKET MATERIAL

Introduction
An article in Engineering Technology in the December 1998 issue prompted this case
study. An original problem in engineering, that of sealing junctions in pipes carrying
steam at high temperature and pressure had long been solved by the use of a substance
known as ‘asbestos’. The new problem that arose was the discovery that the use of
asbestos created a very serious health hazard, and many European Union countries
imposed restrictions on the use of asbestos including a total ban on certain types of
asbestos or its use in particular applications. This report will consider a solution to
the problem from a Bavarian company.

The name asbestos comes from the Greek and means ‘not extinguishable’, and is
applied to a fibrous form of several minerals and silicates of magnesium. These fibres
can be moulded or woven into fabric, and the material was in use as early as the
second century BC. It is a poor heat conductor and non-flammable, making it a useful
material for fireproof clothing and insulation. 75% of the world supply is mined in
Quebec, usually by open pit mining.

The fibres are separated from the ore by crushing and air suction and by vibrating
screens. It is graded into 7 classes by length of fibre. The longest is used in fabrics,
the shortest for moulded products, including gaskets.

Exposure to asbestos fibres and dust can cause asbestosis, a disease of the lungs,
which can then lead to lung cancer and mesothelioma, a deadly form of cancer.
Research into obtaining satisfactory substitutes has accelerated, because of the health
risks posed by the use of asbestos leading to the present ban on the major use of
asbestos with a leaning towards a total ban within a very short time.

Although asbestos has been used in many applications it was found to be particularly
useful in making pipe joints leak-proof. Once installed, it would not be likely that the
asbestos would present a health hazard, this would occur in the processing.



                  ORE                   PROCESS                 GRADED
                                                                 FIBRES

The processing system consists of a number of sub-systems:



                                                                                 CLASS
                                             AIR              FIRST
      ORE               CRUSHER                                                   ONE
                                           SUCTION           SCREEN
                                                                                 FIBRE




DET: Technological Studies: Case Study (Higher)                                            5
Transmission of Steam



                  BOILER                 PIPELINE             WORKPLACE




The pipeline will have one or more joints in its length. One such joint is shown in the
sketch.
                                        FLANGES

                                                                  PIPE




Pipe joints are usually made by means of flanges as shown which are bolted together.
If a surface imperfection on one flange lines up with a similar imperfection on the
other, leakage occurs. This may not only be wasteful, but also hazardous to health
due to heat or toxicity. This problem was overcome by the use of a gasket. This is a
sandwich of soft metal sheets and asbestos. When the two flanges were bolted
together, squeezing the gasket, a gas tight joint was obtained. For many years it was
believed that this particular problem had been solved. Then evidence began to be
built up showing that asbestos was a dangerous substance for any person working
with it as explained above.




DET: Technological Studies: Case Study (Higher)                                       6
Analysis and Description

As the ban or severe restriction on the use of asbestos took effect in Europe
manufacturers searched for a material for gaskets that would replace asbestos in its
many applications. Such a material would have to be competitive in performance and
be safe and easy to use. A number of alternatives have been developed, but with such
characteristics that separate solutions were required for each application. This meant
higher costs or poorer performance when compared with asbestos. Fibre-based
gaskets can be used up to 250oC, which is relatively undemanding. PTFE-gaskets
resist temperatures up to 250oC. Gaskets made from metal reinforced graphite have
been successfully used in applications up to 450oC, but with a restricted sheet size and
increased costs of installation and maintenance. The multi-layered steel gasket has
been successfully used in vehicle cylinder heads, but the process is expensive and the
motor industry is subject to frequent changes of vehicle engine design.

These developments have taken place over the past 20 years, but it is only recently
that a soft non-metallic gasket material has been developed offering high residual
stress and flange adaptability with high heat and chemical resistance. Five years of
intensive research by Frenzelit-Werke Gmbh in Bavaria in conjunction with DuPont
has led to the marketing of this material under the name of NOVATEC Premium with
KEVLAR.

Graphite up to 75% is the main component reinforced with DuPont KEVLAR fibre.
Graphite has excellent chemical and temperature resistance, but in practice it has a
tendency to brittleness, and under high loads can ‘run’. The reinforcement with
KEVLAR makes it possible to reproduce a material, which does not require binders to
make it resistant to creep under compression and to chemical attack. It is highly
stable in operation, giving longer intervals between inspections and lower operating
costs.

In comparison with other non-asbestos materials, these gaskets can withstand double
the residual compressive stress. An initial 50N/mm2 can be maintained after repeated
exposure to temperatures of 300oC. This means that the initial tightness of the bolts,
the surface pressure and the frictional tightness remain virtually constant. For
applications with high demands on residual stress, the new material promises longer
service life, lower maintenance, and a higher fail-safe threshold.

Conventional gaskets have a low permeability to gas by virtue of the binders used.
However these binders have an adverse effect on the material’s residual stress
capability. With NOVATEC KEVLAR there is no longer a need to try to balance
these properties as the graphite/KEVLAR combination not only has much lower
permeability, but also maintains excellent residual stress values.

Because of the high graphite content resistance to almost all chemicals is excellent.
In 6 months use with highly corrosive nitric acid at 100oC there was no deterioration
or loss of performance. Temperature figures in manufacturers brochures still reflect
asbestos technology and industry standards quote temperatures up to 200oC.
NOTVATEC Premium with KEVLAR has been shown to operate reliably up to
360oC.



DET: Technological Studies: Case Study (Higher)                                         7
Material                                          Loss of Tensile Strength
KEVLAR                                            Less than 25%

ASBESTOS                                                   30%

Alternative asbestos-free material                Between 45% and 80%

Table showing relative strengths of gasket material. This standard test consists of
determining tensile strength before and after immersion in water at high temperature.

The security of a flanged joint depends on a uniform distribution of tensile strength
across and along the material. However fibrous reinforcement material is processed
so that the fibres lie in one direction, and like the grain in wood there is a greater
strength along the line of the fibres than across it. KEVLAR fibres are introduced in
such a way that the tensile strength is uniform in all directions. This greatly improves
performance and reliability.

It was mentioned earlier that the gasket is required to compensate for surface
irregularities in the flange. There is also a temperature distribution between the inside
of the pipe where the steam is conducted and the outside of the flange, which is in
contact with the atmosphere. NOVATEC KEVLAR overcomes these negative effects
because of the lubricative and heat conductive properties of the large graphite
component.

Since no metal is used in NOVATEC KEVLAR it is easily cut or punched using
water jet or laser equipment. It can be made up in sheets of 2m X 1.5m enabling large
single piece gaskets to be made. The KEVLAR makes handling easier by virtue of its
inherent strength and flexibility, and the possibility of damage during installation is
very much reduced.




DET: Technological Studies: Case Study (Higher)                                         8
Social, Economic and Environmental Effects
Occupational diseases are illnesses resulting from job related exposures and form a
large part of environmental diseases. Awareness of such diseases arose from the more
intense exposure in the workplace to the factors causing illness, and the onset of many
diseases was made more apparent during the Industrial Revolution of the 19th
Century. Examples include silicosis, a lung disease of miners due to breathing in of
coal dust, skin cancer in chimney sweeps exposed to soot, bone disease due to
exposure to phosphorous in match making and many others. The cancer forming
activity of asbestos has now been fully recognised, even though it may take years to
develop. Asbestos workers who smoked also had a greater chance of contracting lung
cancer. The deadly nature of asbestos not only affects the workers in the asbestos
industry, but also builders erecting or maintaining buildings, and the general public
living in houses which have asbestos in the fabric.

The partial ban and the forthcoming total ban on the use of asbestos material will
bring about a serious economic loss for the companies and workforce involved in its
extraction, processing and distribution. Many of these companies will face large bills
in compensation payment. However the benefits to the environment and to the public
at large of a complete ban on the use of asbestos are obvious.

Asbestos was such a valuable material in a wide variety of applications that a search
for alternative materials occupies many companies. It is unlikely that a single
material to replace it universally at similar economic levels will be found. The result
is increased costs in certain industries and uses. However the opportunities to adapt
new materials with enhanced properties is an incentive to progress, and a company
that succeeds in solving particular applications at a reasonable financial level can be
assured of good returns to the benefit of workers and shareholders.

In the case of the new gasket materials being considered, the main component is
graphite. The total quantity of graphite required is small, as was the amount of
asbestos in gaskets compared wit the use of asbestos in insulation and building.
However the large scale use of asbestos would keep costs down, whilst an increased
demand for graphite might have the opposite effect. Graphite does occur naturally,
but mixed with metallic ores, and it is usually manufactured by baking petroleum
coke and coal tar pitch for many weeks at high temperatures. The energy requirement
is therefore high with the consequent drain on finite earth resources and a contribution
to global pollution.

KEVLAR is a plastic material and therefore like graphite is a by-product of the
petrochemical industry. The opportunities for employment and economic advance are
provided at the cost of a further drain on the world supply of fossil fuels and another
area of contribution to pollution.




DET: Technological Studies: Case Study (Higher)                                           9
Conclusion
The problem of finding a replacement for asbestos in gaskets, because of its high
health risk, appears to have been well solved by the development of NOVATEC
Premium with KEVLAR, a combination that will not only take the place of asbestos,
but will offer an improved performance. It has excellent residual stress, low gas
permeability, high chemical resistance and thermal stability. The company has
developed it claims that it can be used for 80% of all gasket applications. It has a
long service life, high reliability, is easy to fit and is very suitable for standardisation
across a range of applications.

The economic arguments for using NOVATEC Premium with KEVLAR are
considerable, as instanced by a major German Firm, which is realising cost savings in
the order of 30%. A multinational Electronics Company is using the material for
critical operation involving thermal cycling, and expects that this material will bring
about a ten-fold improvement in service life. A truck manufacturer is saving money
and oil (from curing leaks) through the use of NOVATEC Premium with KEVLAR.

Frezelit-Werke Gmbh & Co have scored a notable success with the development of
NOVATEC Premium with KEVLAR, but at present it is applied in a specialised field.
This development has been brought about because of the health and environmental
dangers associated with asbestos, but the applications which made use of the unique
properties and availability of asbestos are so numerous that the development of a
material to replace all those uses is unlikely to happen. Developments like
NOVATEC Premium with KEVLAR however do present an opportunity to replace
asbestos in particular applications with a material which has improved properties and
performance compared with asbestos, using existing technology, and at lower cost. In
these enlightened days it is confidently expected that the companies concerned will
pass on benefits to the workforce and consumers, and keep health hazards and
pollution factors as low as possible.




DET: Technological Studies: Case Study (Higher)                                            10
Acknowledgements

The following sources of information for this project were used:

Technology For All. Short Course Exemplar Material issued by SCCC

Technology Studies. System and Control. SCCC

Advanced Design and Technology. Longman

Engineering Technology. December 1998

Microsoft Encarta 95 CD-ROM.

Internet - various sites, including
http://www.phepsweb.com
http://www.frenzelit.com




DET: Technological Studies: Case Study (Higher)                     11
DET: Technological Studies: Case Study (Higher)   12

				
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