Non Destructive Test

UNIVERSIDAD TECNOLÓGICA DE ALTAMIRAOrganismo Público Descentralizado de la Administración Pública Estatal

NON DESTRUCTIVE TEST

“VISUAL TEST”

Members:

Balboa García Maximiliano

Enríquez Arano Aarón

Gallardo Cruz Leonardo

Professor:

Francisco Estrada Casttillo

Group and grade: IMI-10° A

Altamira, Tamaulipas.


VISUAL INSPECTION

Visual inspection is the oldest technique among the non-destructive testing, and also

the most used by its versatility and low cost.

It used as a main instrument, the human eye, which is often supplemented with

magnification, lighting and measuring instruments.

This technique is, and has always been a complement to all other non-destructive

testing, since often the final evaluation is done by visual inspection.

Visual inspection is a sequence of operations that are performed throughout the

productive process, and which aims to ensure the quality of welded joints. It starts with

the receipt of materials in the warehouse, continues during the whole process of

welding and ends when the inspector examines and marks, if required, the areas repair

and complete the 'inspection report'.

Consists in

a. Measurement of the dimensions of welded joints.

b. Detection of possible cracks or surface discontinuities of the welding.

c. Register and mark the positions of defects for repair, or discontinuities that

require further inspection and verification by other techniques of the E.N.D.

TERMINOLOGY

Discontinuity: Any interruption or local variation of continuity or normal physical

configuration of material.

A: discontinuity can be any change in geometry, holes, cracks, composition, structure

or properties. Some discontinuities, such as holes or shapes of surfaces, are

considered as intentional in design and do not require to be inspected.

Volumetric discontinuity: Described because they have three dimensions or volume.

Discontinuities Planar: Described because they are thin in one dimension and in the

other two dimensions.

Relevant discontinuities: Are those that for some of their characteristics (size, shape,

etc.) must be interpreted, evaluated and reported.


Not relevant discontinuities: Are those who for some of its features are interpreted

but not evaluated, and that they should be registered.

Linear discontinuities: Are those with one length greater than three times its width.

Round: Are those of elliptical or circular form that have a length equal to or less than

three times its width.

Default: Is a discontinuity exceeding the established acceptance criteria, or that could

lead to material or equipment fails when it is put in service or during operation.

Porosity: Discontinuity of the type of cavity formed by gas trapped in the weld metal

solidification.

Fusion, incomplete (lack of fusion): Two-dimensional discontinuity caused by the

lack of union between weld and base metal cords, or between the weld beads. It is the

result of techniques, preparation of the base metal, or design of the inappropriate

Board.

Cracks: Occur in the base metal and metal contribution, when the localized stresses

exceed the resistance of the material. Most of the rules used in ANCAP considered that

the cracks are, regardless of their length, defects and therefore once detected must be

removed, disposed of.

(a) cracks in hot: developed during solidification and its propagation is intergranular

(between grains).

(b) cracks in cold: develops after solidification, they are commonly associated with

precariousness by hydrogen. They spread among and through the grains (inter and

transgranular). According to its form, the cracks can also be classified in:

1 longitudinal fissures: are parallel to the axis of the weld. Submerged arc welding, they

are commonly associated with high speeds and are sometimes related to problems of

porosity, which are not displayed on the surface.

2 transverse cracks: usually are the result of efforts due to contractions longitudinal

acting on low ductility welding metals.


3 craters: occurs when the arc is incorrectly terminated. They usually have a star. They

are superficial, are hot and usually form networks with star-shaped.

4. of throat: are longitudinal fissures located on the face of the weld. Usually, but not

always, cracks in hot.

5. from the edge: are usually cracked in cold. They are initiated and propagated from

the edge of the welding, where contraction is concentrating. They start at right angles

to the surface of the base metal.These fissures are usually the result of contraction

thermal heat acting in the affected area (ZAT).

6. from root: longitudinal, are at the root of the weld or on the surface of it. They can be

hot or cold cracks. Under the lace fissures and cracks in the ZAT: are usually cracks in

cold formed in the base metal ZAT. They are usually short, but they can be joined to

form a continuous fissure. Which are given under the cord can become a serious

problem when present: hydrogen, little ductile microstructure and high waste

efforts. Both can be hot or cold cracks. They are found at regular intervals under the

welding and also by the outline of the ZAT where waste efforts are maximum.

Undercut: Usually associated with excessive currents and/or improper welding

techniques. The undercut is a notch or gutter or Groove located on the edges of the

weld; It is a hub of tensions and also decreases the thickness of the plates or pipes, all

of which are detrimental.

Overlap: Is the portion that protrudes from the metal welding beyond the limit of the

welding or its root.

Misalignment: This discontinuity occurs when welded joints butt presents the surfaces

that should be parallel misalignment; can also occur when welded two pipes that have

been presented eccentrically, or possess ovalizaciones.

Excessive penetration: In a simple welding from one side only (typically welds of

pipes), this discontinuity represents an excess of metal produced at the root of welding

that leads to descolgaduras of molten metal.

APPLICATIONS

Visual inspection is the first step in any evaluation. In general, the evidence does not

Destructivas establish as a prerequisite perform a visual inspection, normally the first

thing we say is "Let me see how it is (the appearance)".


For many objects, the visual inspection is used to determine the amount, size, shape or

configuration, surface finish, reflectivity (reflection), features color, adjustment,

functional characteristics and the presence of surface discontinuities.

In general, inspections with light energy are used primarily for two purposes:

1) the inspection of surfaces exposed or accessible objects opaque to (including most

partial assemblies or finished products), and

(2) the inspection of the interior of transparent objects (such as glass, quartz, some

plastics, liquids and gases).

The power, petrochemical industry, transport and infrastructure, where there are

corrosive environments, temperature or where is contained pressure, required visual

checks.

For example, the energy industry relies considerably on transfer, Exchange and

accumulation of heat through several States of water, liquid or gas. First, manufactured

pipe or pipes and containers to contain pressure. They are then subject to conditions

such as fatigue, corrosion and erosion that may cause failure during its useful life.

Therefore, the visual check of the raw material, before manufacturing, during

manufacture and during exams scheduled periodically during the life of the product, is

considered appropriate.

Also, the discontinuities of manufacture, during the welding process, are very

important. Whether during the process of the material or service life, the discontinuities

can be prevented or removed. During the service, the inspector must differentiate

between deficiencies in manufacturing, such as porosity, slag, undermined, etc. and

failures of service, such as wear, cracks, erosion, corrosion, etc.

The petrochemical industry has the same considerations, but with greater emphasis on

corrosion which causes wear and tear on tanks, containers subject to pressure, pipe or

tubing.

In the transportation industry, there is one greater emphasis on change, from contained

pressure and corrosive environments to efforts by loads and fatigue of

components. While the hydraulic fluid, Corrosives, such as saltpeter environments, etc.

are a concern, the use of aluminum, manganese, tungsten, etc. emphasize cracks by

fatigue and wear.

Infrastructure, including buildings, bridges, tunnels, monorails, etc., are more focused

on the structural integrity of support columns, beams, walls and the obstruction of ducts

(duct or pipe) fluid transfer systems or culverts.


Applications in the steel industry require research inherent failures and losses in

dimensions, based on a large volume. The practical visual testing looks for general

attributes on the surface. But due to the large volumes, optics, laser and computers are

the support of the inspector.

Within the extensive range of visual inspection of industry application, include the

following areas:

Visual inspection of welding in manufacturing (quality control of finish, shape and size).

Mechanical inspection of all types of pipe in the mounting and the operation supports.

Inspection service of equipment and components, hardware heat exchangers.

Detection of leaks in piping systems and flanged joints.

Detection of corrosion, erosion or degradation of the service in pumps, valves, piping,

structures, etc.

Control of finishing of components during manufacture: surface condition, absence of

defects, Assembly, packing, etc.

Detection of foreign objects inside equipment and components that may affect its

function.

Visual inspection using non-destructive testing personnel have remote viewing

equipment type Videoendoscopio Techno PackTM X (probe 8mm in diameter and 4.5

meters in length).

WITH RULES

UNE-EN-ISO: 6520-1:2009 classification of geometric imperfections.

Part of the ISO6520 standard is the basis for a classification precise description of the

imperfections of welding, with the goal of avoiding confusion, the types of imperfections

are defined with explanations and illustrations as necessary. Metallurgical

imperfections are not included.

UNE-EN-ISO: 8596:2010 visual acuity test.

It gives a series of optotipos Landolt ring and describes a method to measure the

distance of the visual acuity in daylight for the purpose of certification conditions or

license. It is not designed for the use of clinical measurements or the certification of

blindness or visual impairment.

UNE-EN: 13927:2003 non-destructive testing. Visual essay. Teams.


Describes general requirements for equipment used in visual inspection. The use of

equipment is required in visual inspection when:

Objects, whether by themselves or taking into account environmental factors

visually inaccessible, should become accessible for viewing.

The sensitivity of the test is insufficient.

An image registration is required.

This European standard also includes the verification of the equipment.

UNE-EN-ISO: 17637:2011 non-destructive testing of welded joints. Visual

examination of fusion-welded joints.

Visual inspection for fusion welding of metallic materials. You can also apply to visual

inspection of the union prior to welding.

UNE-EN: 1370:2012 Foundry. Examination of the surface State.

Specifies methods for the examination of surface condition (roughness and surface

discontinuities) of casting parts.

UNE-EN-ISO: 5817:2014 welding. Levels of quality for imperfections.

Levels of quality, are set so that it allows their application to a wide range of welded

constructions. They are designated by the letters B, C and D. the level of quality B

corresponds to the highest requirement on after welding

UNE-EN: 13018:2001 non-destructive testing. Visual inspection. General

principles.

Describes the General principles for the direct, indirect and visual control, when it is

used to determine if a product meets the specified requirements (e.g.: State of the

surface of the workpiece, alignment of the surface point, forms part). This standard is

not applicable to visual examination related to the interpretation of the results of any

other method of destructive testing or not destructive.

REQUIREMENTS AND CONDITIONS

REQUIREMENTS FOR VISUAL INSPECTION

1. Visual acuity. The inspector must have sufficient visual acuity to perform a

proper inspection.


2. Team. Visual inspection may require the use of special tools or equipment

3. Experience and instruction. Visual inspector must have sufficient knowledge

and ability to perform the test.

PREREQUISITES FOR VISUAL INSPECTION

1. Procedures. The development of uniform test methodology should cover the

procedures and criteria of acceptance, which have resulted in consistency and

certainty.

2. The certification programs. It is desirable to have the visual inspection staff

formally certified.

3. Security. Visual inspectors should receive training in welding safety practices.

CONDITIONS AND EXCEPTIONS

Basic characteristics of the human eye

The optical instrument commonly used in visual and optical inspection systems is the

human eye. The eye is an optical instrument that has a variety of automatic settings,

which allow you to adapt and provide a defined vision, even varying intensities of

illumination.

The eye can be compared with a radiation detector, performs a frequency analysis and

measured amount and direction. The light is invisible until it finds

The components of the human eye, with its main functions for vision, can be compared

to the parts of a camera.

The limits of the vision are: intensity threshold, contrast, viewing angle and threshold

time.

• Threshold intensity is the level lower than of brilliance that the eye can see. It

depends on recent exposure to light.

• The contrast is the difference in the degree of brilliance. The eye is sensitive to the

percentage rather than absolute changes in brightness.

• The viewing angle. It is the size of the angle formed by the ends of the object you are

viewing. The smallest angle, is the most difficult to see.

• The threshold time. It is the minimum time that a picture should be exposed so that

the eye can see it. It varies with the size of the object.


Eye fatigue is accelerated by efforts to do with intensities of light in very low or very

high levels, and for their efforts to see wavelengths of light outside of the optimal

frequency range.

Conditions that affect the visual inspection

Mentioned that an important environmental factor that affects the Visual inspections is

the "lighting". Frequently, the emphasis is placed on variables of equipments such as

the angle of view of a borescope or the degree of amplification lighting is incorrect, the

amplification

Other conditions, such as processes experience and health contribute to the accuracy

of a visual inspection or cause discomfort and fatigue of the inspector.

Attributes of parts that can affect visual inspection

The Act of seeing depends on the amount of light entering the eye. Visual inspections,

the amount of light can be affected by distance, reflection, brilliance, shape of the

inspected object.

Cleaning

Cleaning is a basic requirement for a good visual inspection. It is impossible to get

Visual data through layers of opaque dirt, unless cleaning; under discussion Cleaning

can typically be done using mechanical or chemical means or both. Cleaning avoids

the risk that discontinuities are not detected and improves customer satisfaction.

Color changes

The critical evaluation of color and color change is one of the basic principles of the

majority of Visual inspections.

Corrosion or oxidation of metals or organic materials deterioration is often

accompanied by a change in color, imperceptible to the eye.

Condition

Grinding, milling, lapping, chemical attack, cleaning with sand, grit, etc., and forms

turned, are all possible surface conditions affecting the ability to see it. There are

finished surface comparators, showing various conditions.

Size

If the object is larger than the light beam, will be required multiple steps.


Temperature

Excessive heat obstructs the view, this is due to the distortion of the heat wave. Given

a desert environment and water in a reactor vessel, both can produce distortion due to

heat wave.

Environmental factors

Reflections and shadows of walls, ceiling, furniture, and equipment must be c or room

will be too dark to make it practical. The values of 40 to 60%; floors not less than

20%; desks, benches and team d

Physiological factors

Effects of fatigue

Seeing is not the passive formation of an image, it is an active process in which the

observer keeps tracking personal actions through a type of news feed, so perceived

things can be altered by the actions of the observer.

UTENSILS

GAUGES OF WELDING - BRIDGE CAM

FEATURES

With this instrument, it is possible to make the following measurements, either in inches or mm:

Preparation 0 to 60 ° angle

Excess weld metal (capeo size)

Depth of cut

Depth of holes

Size of fillet weld

Length of fillet weld

Desaliniamento (high-low) measures General linear up to 60 mm or 2 inches.


GAUGES OF WELDING - HI / LO

TECHNICAL CHARACTERISTICS

It allows to measure the internal alignment of 2 pipes

Cut radiographic rejections after alignment tests

It measures the internal misalignment of pipe before and after the tracking

Graduated in English units on one side and metric on the opposite side

New slim design, is 30% lighter and made of stainless steel

It quickly measures the internal alignment in four steps

It quickly measures the external alignment in four steps

Effective measurement in internal spaces

FILLET WELD GAUGE

FEATURES

Measurement of solder fillets used to be a complicated process and not very effective gauges, it

already does.

This meter uses an adjustable arm, which slides at a 45 ° angle to the measurement of the

length of the weld.

Simply adjust the arm until it touches the bottom of the vertical leg. The meter is calibrated to

32avos, with metric equivalents given settings, to obtain more accurate readings.


WELDING - V-WAC GAUGE

V-WAC - welding gauges measure the depth of the lower court, the porosity of comparison, the

amount of porosity for every inch linear and height of the Crown.

V-WAC - welding gauges can be purchased separately or as part of a complete set of 7 welding

gauges, which allow them to confirm if your welds conform to the required specifications.

Depth gauge of Hole


Measuring range 0 '' - 10 ''

Graduations of 0.001 "

Precision which meets or exceeds the Federal specifications for USA

Cover continuous for golf of 1/2 inch

RPM counter

Even pressure throughout the trip from the measurement araves

It has 6 extensions of roll in moulded case

Microprobes for.062 small diameter holes -.025

Exchangeable bases

Available in English system


PITTING CORROSION GAUGE


Range of 0 to 1/2 '' increments from 1/64 "and 0.020"

The arm can be set anywhere to any dimension

Built in stainless steel

Compact since it fits in shirt bag and comes with a pocket protector

It has useful formulas on the front and its equivalent decimal on the back

DIMENSIONS

Inspection of the 100%-full examination of all the weld bead specified.

Specimen of 300 mm x 300 mm x 2.5 mm

Lace size: 300mm

Average of the width of the lace 21mm

INSPECTION PROCEDURE

a. cleaning:

Escobillado manual, with carbon steel brush. Then clean with solvent (spray, or

with damp cloth that is free of lint). Finally dries to the environment; According to

the standard ASTM E-165 annex A1.Respective drying and cleaning are carried out


on each side of the weld bead, at a distance of 2 "from the center of lace of welding

for both sides.

b. Note:

Method: direct.

To the naked eye or with Magnifier (Loupe).

Natural and artificial light of Lantern. 15fc (1000 lux) on the observed surface

minimum intensity.

Inspection distance: 30cm (12 ") maximum.

Inspection, greater than 30 ° angle.

c. evaluation:

The evaluation will be done in accordance with AWS D1.1 - 2004 section 6

THEORETICAL FOUNDATION

Types of light

The sources of light for visual and optical inspection can be divided into four

categories: incandescent, Luminescent, polarized and coherent.

Incandescent light

Incandescence is the emission of light due to thermal excitation of atoms or

molecules. Incandescent light sources include filament lamps, gas mantles, lamps,

Luminescent piro and carbon arc lamps lamps.

Luminescent light

The luminescence is a simple Valence electron excitation. Luminescent light is more

monochromatic than the incandescent light.

Luminescent light sources include the discharge gas, laser, LEDs (LED) lamps


Polarized light

Polarization is a phenomenon in which a ray of light is altered through a medium or to

be reflected vibrating in all directions surrounding his career, only makes it in parallel to

a flat plane called privileged directions of polarization.

Coherent light

Coherent light, such as that produced by a laser, is visible light or radiant energy with a

high degree of phase coherence. While the light produced by the majority of light

sources has a wide spectrum and produce a divergent lit area, laser light or phase it is

aligned.

According to the instruments that are used as an aid to vision, and the distance (or

access) having between the inspector and the object of study, the Visual inspection

can be divided into two groups:

•Inspeccion direct Visual


•Inspeccion remote Visual

The first inspection is done at a short distance from the object, taking full advantage of

the natural visual ability of the inspector. Magnifiers, microscopes, lamps or lanterns

are used, and frequently measuring instruments such as calipers, micrometers and

gauges are used to measure and classify the conditions encountered.

Remote visual inspection is used in those cases in which has no direct access to the

components to inspect, or in those parts in which, by its design, it is very difficult to gain

access to its internal cavities.

This type of inspection is widely used in the industry to check the internal state of the

reciprocal engines, stationary turbines, compressors, pipes of boilers, heat exchangers,

internal solders, tanks and valves among others.

Remote visual inspection is widely used for internal inspection of Jet engines in the

aeronautical industry. The State of the combustion chambers, the stages of

compression and turbine stages can be diagnosed through this inspection, without

making big you destapes or disassembly.

Rigid or flexible borescopes and videoscopes fiberscopes (optical fiber), are used with

which, through a tube adapted to a digital camera, you can reach most internal cavities

and places inaccessible to the inspector.

Although it is not a rule, some rules as the ASME and the AWS, they require a

qualification and certification of personnel responsible for performing the test of Visual

inspection, where takes into account hours of experience of the individual to certify and

visual acuity (corrected or natural) that this can be certified.

Personnel certification standards that involve this essay include the ISO-9712 and the

ANSI/ASNT CP-189.


ADVANTAGES AND LIMITATIONS

Advantages

The main advantages of the visual and optical inspection are:

- Almost everything can be inspected, to some degree.

- It can be very inexpensive.

- It may be relatively simple equipment.

- It requires a minimum of training.

- Far-reaching uses and benefits

Limitations

The main limitations of the visual and optical inspection are:

- Only surface conditions can be assessed.

- Effective supply of lighting is required,

- Necessary access to the surface that needs to be inspected.

CONCLUSIONS

The non-destructive testing allow to know before one piece fails, possible defects or

imperfections present.

The importance and advantage of the non-destructive testing is that it allows testing

without impairing or mistreat the piece and throwing valuable information from your

state.

Within the welding such tests, practiced much since they allow very accurately to

assess the subsurface and surface finishes and find defects in the process.

The END require qualified and experienced, it is not possible to perform these tests

only having availability of equipment.

Visual inspection is far from being simple 'Watch' of finished welds to assess its quality

as he is commonly thought.

Visual inspection is a sequence of operations that is intended to ensure the quality of

welded joints executed and which covers all stages of the project.

Non Destructive Test

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