1. Introduction
NDT
system is electronic device used to detect defects in products from a variety of metal and non-metallic materials by non-destructive testing.
By defects means discontinuity or
homogeneity of the structure, areas of corrosion
damage. Flaw detectors
are used in various
fields of mechanical engineering, chemical industry, oil and gas, energy, construction, research laboratories
to determine the properties of solids
and molecular properties and in other industries are used to control parts and pieces, welded, soldered and glued joints.
1.1 Overview:
Nowadays, in our world we
have several million kilometers of different type of pipes. Pipes are used to
transport various types of liquid like oil, water for heating premises,
isolated and buried under the ground or water. Moreover metal pipe is widely
used in construction as a structural profile. Pipes are commonly joined by
welding, using threaded pipe and fittings. And during the installation and
joining the pipes, we cannot provide the information about the any leakage and
welding defects from these pipelines. After a few years by detecting the
spillage and corrosion in the metal pipes it can be environmentally hazardous
and expensive to maintain, therefore preventive measures are taken to detect
the any flaw in pipelines before they come of. Non-destructive testing system
takes a significant role in the all type of construction and, oil and gas area.
The damages that occur inside the pipeline it is not only about waste of oil or
gas, it also can be result of pollution of our environment. That can seriously
affect to human nature. Non-destructive testing system detects the flaw or any leakage
inside the pipeline without any disrupting and destroying which will be very
costly and time consuming, NDT system which is use ultrasonic waves is very convenient;
the system is very easy in use, and cheap versus with other ways.
Ultrasonic uses high frequency for transmitting the signal
into a material to detect any corrosion or to locate changes into material
properties. The most common used ultrasonic testing technique is pulse echo. Where
the sound wave transmitted into the pipeline or any material and reflected back
to the receiver switch.
From block diagram that
shown above, we learned that power supply which we will use in this project has
to supply +/-150 DC voltage. We supply the circuit with small DC voltge which
is converted to AC and back to high DC voltage using boost converter. Power
Amplifier is needed to the signal that is generated from tone burst generator.
The amplified signal is needed to excite the transducers. And the signal go to
the transceiver switch that transmits
the signal to ultrasonic sensor throw PIC controlled switch than pulse echo goes back to transceiver
switch reflected by the flaw inside the
pipeline. Echo amplifier is very interesting and important stage in the system.
The reflected signal leaving the transceiver switch is very low, so it needs to
be amplified by echo amplifier using op-amp circuitry. Band pass filter is
needed to propagate the frequencies in range between 20-125Khz. Therefore the
obtained signal will be analyzed using MATLab program.
1.2
Objectives and Aims:
The main objectives of
this project to elaborate the Non-destructive testing system by making the
system portable. Common non-destructive system works with conventional AC Power
Supply. Thus the common NDT system is stationary and it has lack of mobility. Portability
of the NDT system is very big advantage, because now the most of the pipelines
located in areas where there is no conventional AC power supply. Thus big
accent will be given to develop the power supply using battery. We need to
built two circuits which will supply +/- 150 volts from battery and second
circuit should give +/- 15 volts to power the band pass filter, transceiver and
echo amplifier.
- To understand the long range Ultrasonic testing method
- To analyze the each component of the entire system
- To investigate various methods to perform and finish the project
- To develop the hardware prototype for the complete design.
Moreover it should be
able to detect the defects and test the joints between the pipes using
ultrasonic waves. The pipeline is divided into four quadrants and by sending
the signals the system should identify the exact status of the damage. PIC
controlled mode selector has to be designed and built, this circuit will enable
the system to work in different modes. Four different channels will give us
more accurate position of defect. The project
also concentrates on improvements of the non-destructive testing system aside
from portability.
Before the hardware part,
the project will focus firstly on the design and building the circuits , using
preferable software program. All the circuits will be simulated and built until
the desired results have taken.
1.2 Deliverables
- To obtain the power supply circuit that will consist of rectifier, inverter.
- To develop circuit which will include the transceiver switch, power amplifier, echo amplifier and band pass filter.
- To develop PIC controlled Mode Switch
- To join all the circuits and obtain one portable system
2
Methodology
One of the first
non-destructive testing method came into industrial application was X-ray. In this
project ultrasonic signal will be used, which came latest into industrial use. The
method of exciting ultrasound waves were discovered in nineteen’s century by
James Prescott and by Pierre Curie and his brother Paul Jacques. In 1912 the
first application of NDT system was proposed after “Titanic” had sunk. The
Englishman Richardson claimed the identification of icebergs by ultrasound in
his patent applications. During World War I two
French researchers started their development to detect submarines by ultrasound. In 1929 the Russian
Sokolov proposed to use ultrasound for testing castings. Today more than 50
companies are active in industrial NDT. They are still working under strong
competition to the benefit of their customers on their way to improve the
quality of industrially produced parts.
The reason why I am using the
ultrasonic testing, that it has some advantages that other methods do not have.
The Ultrasonic testing it is very sensitive to surface and subsurface discontinuities.
Only single sided access is needed when pulse-echo method is used in the
system. It
has high accuracy in determining reflector position and estimating size and
shape. Therefore, the ultrasonic inspection has several limitations which
includes, Linear defects oriented parallel to the sound beam may go undetected.
Cast iron and other coarse grained materials are difficult to inspect due to
low sound transmission and high signal noise.
2.1 Design
and Testing:
All the design will be done using Pspice program.
Firstly, the information about each component will be collected, to choose an
appropriate components that have good efficiency and low cost. PCB will be
designed in manner that all components of the system compact, using less space.
Because major goal of our project to make the system portable that it will be
easy to carry it from one point to another.
During
the development process, unit testing will be done to ensure all modules are
built correctly. System integration testing will be done after we have built
all the components and combined them into the application.
2.2 Evaluation:
After we
will finish all the testing, we will evaluate the application to check whether
it fulfills our objectives or not.
The Evaluation Phase will be
carried out at every milestone of our project. We will look to this project
from different sides to determine and justify the success. There are basically
several aspects that we going to use in our project:
·
Reliability
·
Feedbacks
from supervisor, moderator.
·
Consistency
with the stated objectives
·
Comparison
with other similar projects
We will
also use the data to analyze the overall performance and the effects of each
smaller part on the whole.
