DT N NDT.pptx non destructive methods on ce

REVIEW OF FABRICATION
TECHNOLOGY
DT AND NON-NDT METHODS

WHAT IS FABRICATION ?
MANUFACTURING PROCESS IN WHICH AN ITEM IS
MADE (FABRICATED) FROM RAW OR SEMI-
FINISHED MATERIALS INSTEAD OF BEING ASSEMBLED
FROM READY-MADE COMPONENTS OR PARTS.

In Fabrication technology, there are 2 main parts :-
1.DT ( Destructive Technique )
2.NDT ( Non Destructive Technique)

DESTRUCTIVETESTING

In destructive testing, tests are carried out to the specimen's
failure, in order to understand a specimen's structural performance
or material behaviour under different loads.

These tests are generally much easier to carry out, yield more
information, and are easier to interpret than nondestructive testing.

Destructive testing is most suitable, and economic, for objects
which will be mass-produced, as the cost of destroying a small
number of specimens is negligible.

It is usually not economical to do destructive testing where only one
or very few items are to be produced (for example, in the case of a
building).

Some types of destructive
testing:
Stress tests
Crash tests
Hardness tests
Metallographic tests

STRESS TESTING :-
Stress testing (sometimes called torture testing) is a form of
intense or thorough testing used to determine the stability of a given
system or entity.
 It involves testing beyond normal operational capacity, often to a
breaking point, in order to observe the results.
Reasons can include:
To determine breaking points or safe usage limits
To confirm intended specifications are being met
To determine modes of failure
(how exactly a system fails)
To test stable operation of a part or system outside standard
usage.

CRASH TESTING :-
The act of crashing under controlled
conditions in order to assess its safety for
passengers
To test (a new product) for safety and
reliability by finding out its breaking point
under pressure, heat, etc
For Eg.: New Car

HARDNESS TESTING :-
 Hardness is the property of a material that
enables it to resist plastic deformation, usually
by penetration. However, the term hardness may
also refer to resistance to bending,
scratching, abrasion or cutting.
Hardness is a measure of how resistant solid matter is, to
various kinds of permanent shape change when a force is
applied.
Common examples of hard
matter are ceramics, concrete, certain metals, and super
hard materials

METALLOGRAPHIC TESTS :-
 A test to determine the structural composition of a
metal at low and high magnification and by x-ray diffraction
methods; tests include macroexamination,
microexamination, and x-ray diffraction studies.
Ceramic and polymeric materials may also be prepared
using metallographic techniques

DT N NDT.pptx non destructive methods on ce

NON DESTRUCTIVE TESTING :-
 Quality control method that does not damage or
destroy the material or product being tested.
 NDT is examination of an object in any manner
which will not damage in future.
 It is carried out to locate the internal defects of
material. Thus NDT give reliability accuracy location
and appearance of defects.

TYPES OF NDT :-
1)Visual Inspection
2)Radiography Technique
3)Ultrasonic Technique
4)Magnetic Particle Method
5)Surface Penetration (Dye) Method

Visual Inspection
 Defects which are easily located by visual inspection are
surface cracks, roughness swells, tears etc.
 Visual Inspection is carried out with the naked eye or using a
magnifying glass.
An inspector carrying out visual examination identifies costing
defects and assign their cause to same foundry operation.
 Visual inspection is simplest, fastest & almost commonly
employed, but it needs greater skill on the part of the inspector
to locate and identify defects.
 Only visual inspection may be sufficient for many castings
such as manhole covers, drains, counter balance weight etc.

RADIOGRAPHIC TEST :-
High frequency radiations of constant intensity are made to fall
on the component to be tested.
Some of radiations which passing through the component are
absorbed by defects & remaining radiations emerges out from
the other side of the metal component.
The intensity of transmitted radiations are usually recorded on
photographic film.
It may be noted that the less darker region represents the
perfect portion.
The image developed on film is called Radiography.
This technique is know as radiographic technique.

This method is used to detect defects in material which
with stand high pressure & temperature.
Eg. REACTOR, PRESSUREVESSEL Etc.

Advantages :-
1) High sensitivity
2) Permanent record on film
3) Adjustable energy level
Disadvantages :-
1) High initial cost
2) Power source required

ULTRASONIC TESTING :-
Ultrasonic inspection is employed to detect and locate defects
such as cavities ,internal bursts or cracks etc.
For operation ultrasonic wave is introduced into the metal and
the time interval between transmission of outgoing waves and
incoming waves are measured with the help of CRO.
In case of defects exists between the top & bottom casting
surface, most of the waves striking this defect will get reflected
from defect, and will reach the receiver probe & indicate a echo
on CRO screen.
This technique is know as Ultrasonic testing.

Advantages:-
1) It is fast & reliable method of NDT
2) This method of locating flaw is more sensitive than radiography.
3) Low speed and high speed of operation
Disadvantages :-
4) Very sensitive to rough surfaces
5) In complex casting the interpretation of oscilloscope traces may not be
easy.

MAGNETIC PARTICLE INSPECTION :-
This method of inspection used an magnetic ferrous
casting for detecting invisible surface or subsurface
defects.
Deeper subsurface defects are not satisfactorily
detected because the influence of the distorted lines
of magnetic flux on the magnetic particles spread
over the casting surface becomes weaker with the
distance.
The defects commonly are thermal crack, grinding
cracks, overlaps, fatigue cracks etc.
This method is very simple and easy technique.

Advantages :-
1. Economical & Portable
2. Simple and easy to perform
3. Fast process
Disadvantages :-
4. Material tested must be magnetic
5. Demagnetization is necessary
Applications :-
6. Applicable to all ferromagnetic material

Surface penetrate liquid method
liquid penetrant inspection (LPI) or penetrant testing (PT), is a
widely applied and low-cost inspection method used to locate
surface-breaking defects in all non-porous materials (metals,
plastics, or ceramics).
The penetrant may be applied to all non-ferrous materials and
ferrous materials, although for ferrous components magnetic-
particle inspection is often used instead for its subsurface
detection capability.
LPI is used to detect casting, forging and welding surface
defects such as hairline cracks, surface porosity, leaks in new
products, and fatigue cracks on in-service components.

ADVANTAGES :-
1. The method has high sensitivity to small surface
discontinuities.
2. The method has few material limitations, i.e. metallic and
nonmetallic, magnetic and nonmagnetic, and conductive and
nonconductive materials may be inspected.
3. Large areas and large volumes of parts/materials can be
inspected rapidly and at low cost.
4. Parts with complex geometric shapes are routinely inspected.
5. Indications are produced directly on the surface of the part
and constitute a visual representation of the flaw.

Disadvantages :-
1. Only surface breaking defects can be
detected.
2. Only materials with a relatively nonporous
surface can be inspected.
3. Precleaning is critical since contaminants
can mask defects.
4. Post cleaning of acceptable parts or
materials is required.
5. Chemical handling and proper disposal is
required.

Eg. Plastics, vessels, tanks etc.

FATIGUE ASSESSMENT OFVESSELS
 IMPORTANT DUETOVESSELS MAY BE SUBJECTED TO
CYCLIC LOADS AND STRESSES.
 CYCLING CAUSES DUE TO :
 FLUCTUATIONS IN OPERATING CONDITIONS
 VIBRATIONS
 LOADING DUETO FLOW OF LIQUIDS AND SOLIDS
AND FLUCTUATIONS
 FLUCTUATIONS DUE TO EXTERNAL LOADING
 FATIGUE ASSESSMENT

PRESSURE TEST
 APPROPRIATE PRESSURE TO BE DETERMINED AS
PER:
 TEST PRESSURE=1.30 [Pd*Sa/Sn* t/(t-c)]
 WHERE: Pd= DESIGN PRESSURE
 Sa,Sn= MAXIMUM ALLOWABLE STRESS ATTEST
AND DESIGNTEMP, N/MM2
 c=CORROSSION ALLOWANCE
 T=ACTUALTHICKNESS OFVESSEL

 TYPES:
 HYDRO PRESSURE TEST (WATER)
 PNEUMATIC PRESSURE TEST (AIR)

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