Visual Tes

UNIVERSIDAD TECNOLÓGICA DE ALTAMIRAOrganismo Público Descentralizado de la Administración Pública Estatal

NON DESTRUCTIVE TEST

“VISUAL TEST”

Professor:

Francisco Estrada Casttillo

Members:

Balboa García Maximiliano

Enríquez Arano Aarón

Gallardo Cruz Leonardo

Group and grade:

Altamira, Tamaulipas.


VISUAL TEST

A visual tesr is the oldest technique between non destructive tests (NDT), and also the

most used for its versatility and low cost.

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

magnification tools, lighting and measurement.

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

(NDT), since often the final evaluation is made by visual inspection.

A visual inspection is a sequence of operations that take place throughout the entire

production process, which aims to ensure the quality or intregrity of welded joints. It starts

with the receipt of materials in the warehouse, continues throughout the welding process

and ends when the inspector examines and marks, if necessary, repair zones and

completes the " inspection report.”

Consisting of......

• Measuring the dimensions of the welded joints.

• Detecting possible cracks or surface discontinuities of the welding.

• Record and mark the positions of defects for repair or discontinuities requiring

further inspection and verification by other NDT techniques.

TERMINOLOGY

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

configuration of a material.

Discontinuity can be considered any change to the geometry, voids or holes, cracks,

composition, structure and properties. Some discontinuities such as holes or surface

shapes, are regarded as intentional by design and need not be inspected.

Volumetric discontinuity: Described as having three dimensions or volume.


Planar discontinuities: Described as thin in one dimension and thicker in the other two

dimensions.

Relevant discontinuities: Those discontinuities who for some of their characteristics

(size, shape or form, etc.) should be interpreted, evaluated and reported.

Non significant discontinuities: Those who for some of its features are interpreted but

not evaluated, and should be registered or recorded.

Linear discontinuities: Those with a length greater than three times its width.

Round: Those of elliptical or circular shape having a length equal to or less than three

times its width.

Default: A discontinuity that exceeds the estabished accepted criteria, or could generate

material or equipment failure when put into operation or during operation.

Porosity: a type of discontinuity cavity formed by gas entrapped during solidification of the

metal being welded.

Fusión Incomplete (or lack of fusion): bidimensional discontinuity caused by the lack of

connection between the welds and base metal or between the weld seams. It is the result

of welding technique, preparation of the base metal, or the improper design board

Fissures: Occur in the base metal and weld metal when localized stresses exceed the

ultimate strength of the material. Most of the standards used in ANCAP considered that

cracks are, irrespective of their length, defects and therefore should be removed or

eliminated once detected.

a) Cracks in heat: develop during solidification and its propagation is intergranular

(between grains or grooves).

b) Cold cracks: develop after solidification, are commonly associated with hydrogen

embrittlement. They spread between and through the grains (inter- and transgranular).

According to its shape, the cracks can also be classified into:

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

are commonly associated with high speeds and times are related to porosity problems, not

shown on the surface.


2. transverse cracks: usually result due to stress acting in longitudinal contractions weld

metals of low ductility.

3. Craters: occur when the arc is done incorrectly. Generally having a star-shaped form.

These surface are formed in heat and usually form star-shaped network.

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

they are cracks formed by heat.

5. Borde: cracks are usually cold. They initiate and propagate from the edge of the weld

where shrinkage stresses are concentrated. They are initiated perpendicularly to the

surface of the base metal. These cracks are usually the result of thermal contractions

acting in the heat affected (HAZ) area.

6. Root: are longitudinal, in the root of the weld or on the surface thereof. They can be

cracked in hot or cold. Cracks and fissures under the cord in the HAZ: cold cracks are

usually formed in the HAZ of the base metal. They are usually short, but they can be

joined to form a continuous fissure. Those given under the cord, can become a serious

problem when present hydrogen, very ductile microstructure and high residual stresses.

Both can be seamless hot or cold. They are found at regular intervals under the weld and

also along the outline of the HAZ where residual stresses are maximum.

Undercut: generally associated with inappropriate techniques and / or currents excessive

welding. The undercut is a notch or channel or recess situated at the edges of the weld; It

is a stress concentrator and also reduces the thickness of plates or pipes, all of which is

harmful.

Overlap: The portion projecting weld of metal beyond the boundary of the weld or root.

Misalignment: This discontinuity occurs when the joints atop of the welded surfaces

should be parallel are misaligned; it can also occur when two pipes are welded that have

occurred eccentrically or have ovality.

Excessive penetration: In a simple welding from one side (typically welding pipes), the

discontinuity represents excess metal provided in the weld root resulting molten metal.


APPLICATIONS

Visual inspection is the first step in any evaluation. In general, non-destructive testing as a

prerequisite establish a visual inspection, usually the first thing we say is "let me see (the

appearance)”. For many objects, the visual inspection is used to determine the number,

size, shape or configuration, surface finish, reflectivity (reflection), characteristics of color,

fit, functional characteristics and the presence of surface discontinuities.

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

1) Inspection of exposed or accessible surfaces of solid objects (including most partial

assemblies or finished products), and

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

liquids and gases).

The energy industry, petrochemical, transportation and infrastructure, where there are

corrosive environments where temperature or pressure is present, visual checks are

required.

For example, the energy industry relies considerably on the transfer and accumulation of

heat exchange through various states of water, liquid or gas. First, pipe or pipes and

containers manufactured to contain pressure. Then they are subject to conditions such as

fatigue, corrosion and erosion that can cause failure during its lifetime.

Therefore, visual inspection of the raw material before manufacture, during manufacture

and tests scheduled periodically during the life of the product is considered appropriate.

Also, manufacturing discontinuities during the welding process are very important. Either

during the process of the material or during the service life, the discontinuities can be

prevented or removed. During the service, the inspector must differentiate between

manufacturing defects as porosity, slag, undercut, etc. and service failures, such as wear,

cracks, erosion, corrosion, etc. The petrochemical industry has the same considerations,

but with more emphasis on corrosion which causes wear on tanks, pressure vessels,

piping or tubing.

In the transportation industry there is a major shift in emphasis from the contained

pressure and corrosive environments up efforts to loads and fatigue of the components.


While corrosive environments such as salt, hydraulic fluids, etc. are a concern, the use of

aluminum, manganese, tungsten, etc. accentuate fatigue cracks and wear.

The infrastructure including buildings, bridges, tunnels, monorails, etc., are more focused

on the structural integrity of support columns, beams, walls and clogging drains or conduits

fluid transfer systems (pipes or tubing).

Applications requiring the steel industry research and losses inherent flaws in size, based

on a large volume. Visual check practice seeks general attributes on the surface. But

because of the large volumes, optics, lasers and computers assist an inspector.

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

following areas:

- Visual inspection of welding in manufacturing (quality control of the finish, shape

and size).

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

- In-service inspection of equipment and components from heat exchangers to

hardware.

- Leak detection systems pipes and flanged joints.

- Detection of corrosion, erosion and/or service degradations of pumps, valves,

piping, structures, etc.

- Control of the finished components during manufacture surface condition, absence

of defects, assembly, packaging, etc.

- Detection of foreign objects inside of equipment and components which may affect

its function.


- Staff doing non destructive testing by visual inspection have remote viewing type

equipment Videoendoscope Techno PACK ™ X (probe 8mm in diameter and 4.5

meters in length).

STANDARS

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

Part of the ISO6520 standard is the basis for an accurate description of weld

imperfections, aiming to avoid confusion, the types of imperfection are defined with

explanations and illustrations where appropriate classification. Metallurgical imperfections

are not included.

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

It gives a series of Landolt ring optotypes and describes a method for measuring distance

visual acuity in daylight conditions for the purposes of certification or license. It is not

designed for use in clinics and for the certification of blindness or visual impairment

measurements.

UNE -EN: 13927: 2003 Non-destructive testing. Visual essay. Equipment.

It describes the general requirements for equipment used in visual inspection. The use of

equipment is necessary when visual inspection:

• The objects themselves or considering, visually inaccessible environmental factors,

should become accessible for viewing.

• Assay sensitivity is insufficient.

• An image record is required.

This European Standard also includes verification of the equipment.

UNE -EN -ISO: 17637: 2011 Non destructive testing of welded joints. Visual examination of fusion welded joints.Visual inspection of fusion welding of metallic materials. It can also apply to the visual

inspection prior to welding attachment.


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

Specifies methods for examining the surface state (roughness and surface discontinuities)

of the molding.

UNE -EN -ISO: 5817: 2014 Welding. Quality levels for imperfections.

Quality levels so as to enable its application to a wide range of welded constructions are

established. They are designated by the letters B, C, and D. Quality level B corresponds to

the highest requirement on the finished weld.

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

It describes the general principles for visual control, direct and indirect, when this is used

to determine whether a product meets specified requirements (For example, surface

condition of the piece, alignment of the facing surface, shape of the piece). This standard

does not apply to visual examination relating to the interpretation of the results of any other

method destructive or non-destructive.

REQUIREMENTS AND CONDITIONS

Requirements for visual inspection

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

inspection.

• Equipment. Visual examination may require the use of special tools or equipment.

• Experience and instruction. The visual inspector must have sufficient knowledge

and ability to perform the test.

Pre-requisites for visual inspection

• Procedures. The development of uniform methodology review should cover the

procedures and acceptance criteria that result in consistency and certainty.


• Certification programs. It is desirable to have staff of visual inspection certificated

formally.

• Security. Visual inspectors should receive adequate training in welding safety

practices.

CONDITIONS AND EXCEPTIONSBasic characteristics of the human eye

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

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

allowing you to adapt and provide a defined vision, even varying illumination intensities.

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

measured amount and direction. Light is invisible until it is finds the components of the

human eye, with its main functions for viewing, can be compared with the parts of a

camera.

Limits of vision are: the threshold of intensity, contrast, viewing angle and threshold time.

• The intensity threshold is the lowest level of brightness as that the eye can see. It

depends on the recent exposure to light.

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

percentage rather than absolute changes in brightness.

• The visual angle. It is the size of the angle formed by the ends of the object being

viewed. The smallest angle is the most difficult to see.

• The threshold time. Is the minimum time that must be displayed an image for the eye

to see. It varies with the size of the object.

Eye fatigue is accelerated by efforts to do with light intensities at very low or very high

levels, and efforts to see wavelengths of light outside the optimum frequency range.


Conditions affecting the visual inspection

It has been mentioned that an important environmental factor affecting visual inspections

is the "enlightenment". Often the emphasis is on equipment variables such as the angle of

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

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

visual inspection or cause discomfort and fatigue inspector.

Attributes of parts that can affect visual inspection

The act of viewing depends on the amount of light that reaches the eye. On visual

inspection, the amount of light can be affected by the distance, reflection, brightness,

shape of the inspected object.

Cleanliness

Cleanliness is a basic requirement for a good visual inspection. It is impossible to obtain

visual data through layers of opaque dirt, unless the cleaning is being examined; Cleaning

typically be done using mechanical or chemical means, or both. Cleaning avoids the risk

that discontinuities are not detected and increases customer satisfaction.

Color changes

Critical evaluation of color and color change is one of the most basic principles of visual

inspections.

Corrosion or oxidation of metals or degradation of organic materials is often accompanied

by a change in color, imperceptible to the eye.

Condition

Grinding, milling, lapping, etching, sandblasting, grit, etc., and shapely forms are all

possible conditions of a surface that affect the ability to see. There are comparisons of

surface finishes, showing various conditions.


Size

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

Temperature

Excessive heat obstructs the view, this is due to the waveform distortion of heat. Since a

desert and water temperature in a reactor vessel, both of which can cause distortion due

to the heat wave.

Physiological factors

Effects of fatigue

Seeing is not passively forming an image, it is an active process in which the observer

keeps track of personal actions through a kind informational gathering, so things perceived

can changed by the actions of the observer.

UTENSILSWELDING GAUGES - BRIDGE CAM

CHARACTERISTICS

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

millimeters:

• Preparation angle 0 to 60 °

• Excess weld metal ( size of Capeo )

• Depth of cut

• Fillet weld size


• Fillet weld length

WELDING GAUGES - HI / LO

TECHNICAL CHARACTERISTICS

• To measure the internal alignment of two pipes

• Radiographic short rejections after testing alignment

• Measures internal misalignment of the pipe before and after tracking

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

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

• Quickly measures the internal alignment in four steps

• Quickly measures the external alignment in four steps

• Effective internal spaces Measurements


METER OF SOLDER FILLET

CHARACTERISTICS

The measurement of fillet welds used to be a complicated process and not very effective

measure, this no longer occurs.

This meter uses an adjustable arm, which slides at an angle of 45 ° for measuring the

length of the weld.

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

to 32nds, with metric equivalents given calibration for more accurate readings.

WELDING GAUGES - V -WAC

Calibrators Welding - V -WAC measure the depth of the lower court, porosity comparison,

amount of porosity per linear inch and crown height.


Calibrators Welding - V -WAC can be purchased separately or as part of a complete set of

7 Welding Gauges, which allow them to confirm whether their welds conform to the

required specifications.

HOLE DEPTH METER


• Measurement Range 0 "- 10"

• Graduations 0.001 "

• Precision that meets or exceeds federal specifications USA

• Revolution counter

• It has six (6) extensions roller molded case

• Microprobe for small diameter holes .062-.025

• interchangeable bases

• Available in English system

•


CORROSION METER


• Range of 0 to 1/2 " in increments of 1/64" and 0.020 "

• The arm can be set anyplace at any dimension

• Built in stainless steel

• Compact as it fits in your shirt pocket and comes with a pocket protector

• It has useful formulas in the front and their decimal equivalents on back

DIMENSIONS

100% inspection.- full examination of all the specified welding beads.

Specimen 300mm x 300mm x 2.5mm

Bead size: 300mm

Average bead width 21mm


INSPECTION PROCEDURE

A.) Cleaning:

Escobillado manual with carbon steel blade. After solvent cleaning (spray, or damp cloth

that is free of lint). Finally dried in the atmosphere; according to ASTM E -165 standard

APPENDIX A1. The respective cleaning and drying are performed on each side of the

weld bead, at a distance of 2 " inches from the center of the weld bead on both sides.

B.) Observation:

Method: Direct.

A naked eye or with a magnifying glass.

Natural and artificial light flashlight. 15fc low intensity (1000 lux) in the observed surface.

Inspect distance: 30cm (12 “) maximum.

Viewing angle greater than 30 °

C.) Evaluation:

The evaluation shall be in accordance with AWS D1.1 - 2004 Section 6

FUNDEMENTAL THEORYTypes of light

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

incandescent, luminescent, polarized and coherent.

Incandescent light

It is incandescent light emission due to thermal excitation of atoms or molecules. Light

sources include incandescent filament lamps, lamps gas mantles, pyro luminescent lamps

and carbon arc lamps.


Luminescent light

The luminescence resulting from excitation of a single valence electron. The

monochromatic light is more luminous than incandescent light.

Luminescent light sources include discharge lamps, gas lasers, light emitting diodes

(LED)

Polarized light

Polarization is a phenomenon by which a light beam is altered to go through a middle or

be reflected vibrating in all directions around your path, but does so in privileged directions

parallel to a plane called plane of polarization.

Coherent light

Coherent light, as produced by a laser, is visible light or radiant energy with a high degree

of phase coherence. While the light produced by most light sources have a wide spectrum

and produce a divergent illuminated area, the laser light is aligned or under.


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

access) that is between the inspector and the object of study, the

Visual Inspection can be divided into two groups:

• Direct Visual Inspection

• Remote Visual Inspection

At first, the inspection is within walking distance of the object, making the most of natural

eyesight of the inspector. Magnifiers, microscopes, lamps or lanterns are used, often

measuring instruments such as calipers, micrometers and gauges are used to measure

and classify the conditions encountered.


Remote visual inspection is used in cases where there is no direct access to the

components to be inspected, or those components which, by design, it is very difficult to

gain access to their internal cavities.

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

reciprocating engines, stationary turbines, compressors, pipes, boilers, heat exchangers,

internal welds, tanks and valves among others.

In the aviation industry remote visual inspection is used for the internal inspection of jet

engines. By this inspection you can diagnose the state of the combustion chambers, the

compressor stages and turbine stages, without major uncovering or disassembly.

Rigid or flexible borescopes, videoscopes and fiberscopes (fiber optic), which are used by

a probe adapted to a digital camera, you can reach most of the internal cavities and places

inaccessible to the inspector.

Though not a rule, some standards like ASME and AWS, require qualification and

certification of personnel performing testing Visual Inspection, where it is taken into

account the hours of experience of the individual to certify and visual acuity (corrected or

natural) that he or she can certify.

Among thrtification standards involving this test are ISO - 9712 and

ANSI / ASNT CP -189.

ADVANTAGES AND LIMITATIONS

Advantages

The main advantages of visual and optical inspection are:

• Almost everything can be checked to a certain extent.

• It is a low cost method.

• You can use relatively simple equipment.

• Minimal training is required.

• Wide-ranging uses and benefits


Limitations

The main limitations of the visual and optical inspection are:

• They can only be evaluated surface conditions.

• An effective light source is required ,

• Access to the surface which needs to be inspected is necessary.

CONCLUSIONS

NDT allow knowing in advance that a part failure, possible flaws and imperfections

present.

The importance and advantage of non -destructive testing is allowing testing without

damaging or mistreat the piece and throwing valuable status information.

In welding it is widely practiced this type of testing, allowing very accurately evaluate

surface and sub - surface finishes and find the flaws in the process.

NDT require qualified and experienced staff, it is not possible to perform these tests only

having equipment availability.

Visual test is far from simple "observation" of finished welds to assess their quality as is

commonly thought.

Visual test is a sequence of operations that is designed to ensure the quality of welded

joints executed and covering all stages of the project.

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