visual advance dacon inspection technologies …

ADVANCE

ULTRASONIC

INSPECTION

DACON INSPECTION TECHNOLOGIES

VISUAL

TESTING

Who we are

Conventional and

Advanced NDT and

Inspection Services

Oil and Gas, Refinery,

Petrochemical, Heavy

Industry, Mining

Over 400 personnel

including more than

300 inspectors

Thailand headquarters

with International

expertise since 1979

DACON INSPECTION SERVICES F O R A L L Y O U R I N S P E C T I O N N E E D S

• Oldest and most widely used inspection Method

• Often eyes of inspector used is the only inspection equipment used

• Direct visual testing: When access allows eyes to be within 25 inch of surface to be

examined and within an angle not less than 30 degrees to the inspection surface

• Remote visual inspection: For inspection of restricted access area’s

Visual Testing



For direct visual testing here are a variety of optical aids available:

• Magnifiers

• Inspection mirrors (when eye cannot be put in recommended viewing range)

• Microscope

• Telescopes

• Camera’s

In addition to this some other equipment is often part of visual testing:

• Vernier calipers

• Micrometer

• Pit gauge

• Scraper

• Digital camera

Visual Testing



Visual Testing

Important factors in Visual inspection:

Visual acuity of the inspector

• Near distance acuity , reading a chart at certain distance

• Color blindness, Ishihara test charts

Lighting conditions

• Measure the light intensity

• Amount of light between 350-1000 Lux depending

on code requirements

• Use of artificial light (flashlights)

• Use of sunlight (mirrors)

Cleanliness of surface

• Normally a clean surface is required to detect discontinuities

• Remove

• Scale

• Paint

• Debris



Visual Testing


Visual angle and distance

• Eyes to be within 25 inch of surface to be examined

• Eyes to be within an angle not less than 30 degrees to the inspection surface

Perception• Length of arrows?

Reflectance and back ground

• The amount of light that is reflected from a background is of great influence

Temperature (heat wave distortion)

• Heat waves coming off from item distorting the view



Visual Testing


Physical comfort

Can be of great influence (applicable for every inspection and NDT examination)

• Comfortable arrangement for inspector will result in greater attention to detail

• Inspection from awkward position may result in missed indications

Inspector may hurry examination in order to get back into comfortable position



Visual Testing

Remote Visual Testing (RVI)

For inspection of inaccessible area’s

• Small bored pipes or tubes

• Pressure vessels or tanks which cannot be

entered (not gas free etc)

Typical equipment to be used:

• Bore scopes

Rigid bore scopes (lens-optic)

• Contains a train of lenses

• Light source at the end of scope to illuminate area of interest

Fiber scopes (fiber-optic)

• Uses a glass fiber bundle

• Light is transmitted to the inspection area via glass fiber

• The light reflected of the object is send back to

viewing end via the glass fiber



Visual Testing


Typical equipment to be used (continued):

Camera’s (Video scopes)

Fiber camera

• Light is transported to area of interest by

fiber optic bundle

• Light waves form the object pass through a lens

and will hit a CCD (charged coupled device)

• CCD converts the waves into electronic signals

which are transmitted to a CCU

• CCU processes received signals to produce

a “picture” on a video screen

• Limitation to the length the fiber bundles

can be manufactured





Mini camera’s

• Light source is placed at the area of interest via electrical wire

• Bigger size required because a ring of light will have to be placed at the tip.

• Length can be bigger than Fiber camera

• Variation the Fiber is transported to area of interest by fiber optic bundle

• Principle of operation similar to fiber camera with CCD

Visual Testing



Visual Testing



Camera’s with Pan, Tilt , Zoom lens

• Are available with long cable and reach (up to hundreds of meters)

• Bigger size, requires:

Motor controls for remote operation of lens

Motor controls for panning and tilting

More light (need to cover several zones for longer viewing distance and for close up)

• Panning and tilting allows the camera to be positioned in almost every position



Visual Testing



Remote operated vehicles (ROV)

• The term ROV is most often used for Remotely operated underwater vehicles

Self propelled sub marine like vehicles that contain a camera and can be

remotely operated

Crawler, tractors



How Can We Help?

Contact

Email : [email protected]

Phone : +66 (0) 33 012 484-7

www.dacon-inspection.com


visual advance dacon inspection technologies …

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