visual advance dacon inspection technologies …
Post on 22-Mar-2022
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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
DACON INSPECTION TECHNOLOGIES
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
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
DACON INSPECTION TECHNOLOGIES
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
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
DACON INSPECTION TECHNOLOGIES
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
Visual Testing
Important factors in Visual inspection:
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
DACON INSPECTION TECHNOLOGIES
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
Visual Testing
Important factors in Visual inspection:
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
DACON INSPECTION TECHNOLOGIES
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
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
DACON INSPECTION TECHNOLOGIES
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
Visual Testing
Remote Visual Testing (RVI)
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
DACON INSPECTION TECHNOLOGIES
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
Remote Visual Testing (RVI)
Typical equipment to be used (continued):
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
DACON INSPECTION TECHNOLOGIES
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
Visual Testing
Remote Visual Testing (RVI)
Typical equipment to be used (continued):
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
DACON INSPECTION TECHNOLOGIES
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
Visual Testing
Remote Visual Testing (RVI)
Typical equipment to be used (continued):
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
DACON INSPECTION TECHNOLOGIES
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