computer radiography for wall thickness measurement

7/28/2019 Computer Radiography for Wall Thickness Measurement

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COMPUTER

RADIOGRAPHY FOR WALLTHICKNESSMEASUREMENT

By

Binu Rajendran


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Why Radiography?

UT gives good results in wall thickness

measurement. But .

1. Smaller diameter pipe?2. Small thickness?

3. High temperature?

4. Insulated pipe?


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Advantages of Radiography Over UT

1. Information is presented pictorially

2. A permanent record is provided which may be

viewed at a time and place distant from the test.

3. Useful for thin sections

4. Sensitivity declared on each film

5. Suitable for any material

6. No need to remove the insulation.

7. Direct contact not required.


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Disadvantages of Radiography

1. Generally an inability to cope with thicksections.

2. Possible health hazard.

3. Film processing and viewing facilities arenecessary

4. Not suitable for surface defects.

5. No indication of depth of a defect below thesurface


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Computer Radiography

Computer Radiography is similar to

conventional radiography in execution except

image handling.

Phosphor image plate is used instead of films.


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The energy falling on the phosphor plate partly

produce fluorescence which is not used and

partly the energy is stored in the phosphorplate as latent image.

After the exposure the phosphor plates areinserted into the CR scanner where the plates

are scanned by the laser beam.


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When phosphor is stimulated by laser beam

the stored energy is released in the form of

light which is collected and fed to the PMT andthe received signal is digitized.


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Principle of CR explained in the

Atom Shell Model

(= shell like structure of electron cloud)

X-Ray

A B

Red laser beam

Blue emittedlight


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Phosphor Scanner Systems

Scanner

rotating mirror

PMT

light-guide

laser

storage phosphor plate


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CR Plates

Protective EBCCoat

phosphor layer

Adhesion layer

Anti-Halo layer

Support PET

Laminate


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Advantages

All the advantages of RT over UT inthickness measurement.

Reduced exposure time with reduced doserequirement.

No dark room or chemical disposals

Electronic archiving and retrieval of theradiographic data.


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Software for measurement and

reporting.

Higher Dynamic Range Reusablephosphor plates.

Centralized or distributed management with

remote access. 50 years of data storage life or even more.


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Profile Radiography

There are two technique for wall thickness

measurement.

1. Tangential Projection technique (edgedetection). Wall thickness is measured from

the image and mathematical consideration

of the geometric enlargement and the wall

thickness is calculated.


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Profile Radiography


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Profile Radiography

Determination of the wall thickness t by

measuring the distance t on the film and

mathematical consideration of the real

geometries. This way is called "Tangential

Radiography" and requires the film to be

applied flat (not adapted to the curvature).


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Radiography Corrosion Monitoring

2. Double Wall technique or Gray value(optical density) comparison.

Without step-wedges and/or specialcalibration-procedures the wall-thicknesscannot be measured but only estimatedfrom the optical density. This method is

often called "Radiographic CorrosionMonitoring" and offers the advantage thatmost of the area of the tube beingdisplayed on the film can be evaluated.


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For both techniques we need to discriminate

between the shades of gray.

How many shades of gray can the human eyevisualize?

Approximately 500 is the number, but this

depends on lighting conditions.We need a tool for better results.


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Rhythm

The Rhythm is a user-friendly software from

GE Inspection Technologies offers advanced

image review tools and data management for

all Remote Visual Inspection (RVI) & X-ray

(including computed radiography, digital

radiography and film digitization) testing

methods.


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Rhythm

A DICONDE complaint software platform.

What is DICONDE ?

Digital Imaging and Communication in Non-

Destructive Evaluation.
http://www.geinspectiontechnologies.com/en/products/software/diconde.htmlhttp://www.geinspectiontechnologies.com/en/products/software/diconde.html


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Rhythm

DICONDE is a standard adopted by ASTM(American Society for Testing and Materials)that provides a format for nondestructive

evaluation (NDE) manufacturers and itscustomers to share image data.

The DICONDE standard encompasses all

NDE specific imaging methods andtechnologies, such as computed radiography,eddy current, ultrasound, computedtomography, etc.


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Rhythm

How DICONDE was derived?

DICONDE is an extension of the DICOM.

Digital Imaging and Communication in

Medicine.


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Rhythm

Dicom created a standardized terminology andframework for permitting the transfer of digitalmedical images and information in a multi-vendor

environment. It allowed physicians to have betteraccess to images and reports from potentiallyanywhere in the world, which in turn, allows them tomake faster diagnosis and better server theirpatients. Patients further benefit when their dataeasily flows through the healthcare providersnetwork or when the patient is referred to anotherphysician and their data can be easily read.


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Rhythm

Rhythm Aquire Rhythm Review Rhythm Archive

Rhythm Radiography


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Rhythm Acquire

Interacts with the inspection source to collect

digital information that it passes on to Rhythm

Review. It contains a database of the relevant

inspection techniques and can control the

inspection equipment.


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Rhythm Review

Accepts data from Rhythm Acquire, other

Rhythm Review workstations, and removable

media, such as CD and DVD.

Provides application tools for analysis,

enhancement, measurement and storage of

received data.


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Rhythm Archive

Provides both on-line and nearline data

storage to allow simplified information sharing

and faster access to information.


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Thickness Measurement Tools

Tangential Projection technique using Rhythm

Image is received from the acquire andreviewed using the measurement tools in

review.


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Tangential Technique


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Thickness Measurement Tools

Material Loss


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Premium Tools

Premium Tools

1. Area Measurement Tools- The area

measurement tools provide the capability tomeasure objects. It separate the object

from the background and calculate the

area.


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Rhythm

Multifilm Inspection Tool This tool provides

capability similar to multifilm technique used in

conventional film radiography.

With the help of this tool you can split the

dynamic range of the selected radiographic

image into two or three exclusive parts for

better visualization and analysis of the image.


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Rhythm

Conclusions: CR systems are not an in-between step in the process of filmreplacement. Computed Radiography is one of

the modalities that will replace film in thefuture. The right solution and choice willcompletely depend on the requirements of theuser. Throughput, environment, infrastructureand workflow are the key factors. Important ishowever that one digital solution does notcompete the other, and both have to be

id d i h i

computer radiography for wall thickness measurement

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