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Gamex 5.0

Program description and operating manual

Issue No. : 1.0Date of Issue : 03 - 2010

Z.U.T. NDT SOFThttp://www.ndtsoft.eu


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Gamex 5.0 Program description and operating manual

Copyright (c) 2009-2010 by Z.U.T. NDT SOFT

All Rights Reserved

Disclaimer

Information in this document is subject to change without notice. No part of this manual may be

reproduced, stored in a retrieval system, or transmitted in any form or by any means electronic or

mechanical, including photocopying and recording for any purpose other than the purchasers personal

use, without prior written permission from Z.U.T. NDT SOFT.

The software described in this document is furnished under the software license agreement distributed

with the product. The software may be used or copied only in accordance with the termsof the license.

Trademarks

The following trade names are referenced throughout this manual:

Microsoft, Windows, Win32, Windows 98, Windows Me, Windows NT, Windows XP, Windows Vista,

Windows 7 are either trademarks or registered trademarks of Microsoft Corporation.

Other brand and product names are trademarks or registered trademarks of their respective holders.

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Contents

1. INTRODUCTION ...4

2. BASICOPERATIONS..6

2.1. PROGRAMINTERFACE....4

2.2. INITIALSETUP..7

2.3. ENTERINGNEWGAMMA-RAYSOURCES.....8

2.4. DESIGNINGOFRADIOGRAPHICTECHNIQUES.............10

2.5. PRINTOUTOFRADIOGRAPHICTECHNIQUES...........17

2.6. CALCULATIONOFACTIVITYTIMETABLES.............20

2.7. CALCULATIONOFRADIATIONDOSES...........22

3. ADVANCEDFEATURES.........24

3.1. EXPOSURECORRECTIONSYSTEM............................................................................24

3.2. CORRECTIONDATAANDTESTRADIOGRAPHS............24

3.3. USINGOFEXPOSURECORRECTIONSYSTEM...........27

3.4. TESTINGMATERIALSOTHERTHANSTEEL.........................28

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1. Introduction

Gamex 5.0 is a professional software program supporting industrial radiography carried out with

conventional radiographic films and Ir-192, Se-75 and Co-60 gamma-ray sources. It provides

comprehensive support for Level 3 and Level 2 radiographic personnel in developing and

implementing high quality radiographic techniques in line with requirements of ASME Code,

Section V and European standards EN 444 and EN1435.

Gamex 5.0 will operate on the following Windows platforms: Windows 98 SE, Windows Me,

Windows 2000, Windows XP, Windows Vista and Windows 7.

The program offers the following functionality:

Optional selection of the applicable code or standard, preferred measurement units and

IQI types.

Editable database to enter parameters of gamma-ray sources used in the laboratory.

Editable database of radiographic equivalence factors for materials other than steel.

Systematic development of radiographic techniques for different inspection tasks.

Automatic check if the user proposed technique parameters are compatible with object

geometry and the applicable code/standard requirements.

Calculation of minimum SFD required to meet the code/standard conditions for

geometric unsharpness.

Calculation of minimum number of exposures necessary for full examination of

circumferential weld in accordance with the applicable code or standard.

Calculation of the single film length compatible with the number of exposures stipulated

for circumferential weld.

Calculation of exposure times for the developed radiographic techniques in dependence

of the tested material thickness, SFD, source type and activity, film type/class, and

preferred optical density of radiographs.

Intelligent correction system enabling adaptation of the exposure calculation algorithm to

the specific testing/processing conditions in the user's laboratory.

Database of exposure correction data collected from test radiographs representing typical

testing conditions encountered in the user laboratory.

Optional exposure time correction for the film edges compensating for reduced

radiographic exposition at the film edges as compared to the film center (the combined

effect of increased source-to-film distance and penetrated material thickness)

Automatic etermination of the IQI values required by the applicable code or standard forexamined material thickness, test conditions and technique class.

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2. Basic operations

2.1. Program interface

After successful installation and registration of the Gamex program on your computer you can

start it by double clicking on the shortcut icon placed by the installer on the Windows desktop.

Fig. 1. Gamex 5.0 shortcut icon on the Windows desktop.

The program main window is displayed from where you can easily reach all its basic functions,

options, databases and help files.

Fig. 2. The main window of the Gamex program.

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2.3 . Entering new gamma-ray sources

Before starting normal program operation you need to enter parameters of your gamma-ray

sources to the program database. To specify parameters of your sources click on the Gamma

sources button in the main window and open the following form:

Fig. 4. Form displaying gamma-ray sources stored in the program database.

When you open this form for the first time you may find there some example entries of gamma-

ray sources which can serve you as templates for introducing your actual data. You may review

this example data by clicking on the Edit data button and edit them to conform your actual

sources. Alternatively you may enter your sources from the beginning by clicking on the New

data button and opening the following form:

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Fig. 5. Entering parameters of a new gamma-ray source.

In theRadionuclide box you have to select the type of radioisotope of your gamma-ray source.

You have to choose one of the three options: Ir-192, Se-75 or Co-60.

In the Source serial No edit field you enter the serial number of your gamma-ray source. It is

normally indicated on the source certificate obtained from the supplier.

In the Source size edit field you enter the size of your gamma-ray source which is indicated on

the source certificate. This value will be used by the program in calculations of minimum SFD

values required by the applicable standard.

In theInitial activity field you enter the initial activity of your gamma-ray source as indicated in

its certificate. The activity value should be expressed in [GBq] units (not in old units [Ci]).

In theDate of initial activity data picker field you have to pick up the date of the initial activity

measurement. This information should be given in the source certificate together with the

activity value.

In the Source container edit field you enter the short identification (symbol/number) of the

container your gamma-ray source was loaded to. It should unambiguously identify the source in

all radiographic works performed in the user laboratory.

After entering all above data click on the OKbutton and find your new source in the table of

sources displayed in the Gamma sources form. To permanently save the new source in the

program database click on the OKbutton in the Gamma sources form.

After entering to the program database parameters of all gamma-ray sources used in your

laboratory you can start all basic program operations. Some more advanced program functions

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will still require additional setup information based on test radiographs and other auxiliary data.

This subjects will be covered inAdvancedsection of this manual.

2.4. Designing of radiographic techniques

The main function of the Gamex program is comprehensive support of professional

radiographers in developing radiographic techniques in line with requirements of specified code

or standard. As was mentioned above the possible options are European standards EN 444/ EN

1435 or ASME Code, Section V.

To start the technique designer click on the Technique designerbutton in the main window and

open the form titled Radiographic technique designer. During subsequent steps of technique

development the program will supervise your choices and warn you in case of breaking the

standard rules or other restrictions. Additionally, it will give you context sensitive hints

concerning most important technique parameters. This specific functionality is accomplished

with small buttons with question marks located in the vicinity of parameter fields. By clicking onthe corresponding button you get a short info on restrictions imposed by the standard on the

parameter values. When you enter parameter value to the program it automatically checks it

against the standard rules. The verification result is signaled with a color of question mark on the

corresponding hint button.

If the color remains black it means that the program hasn't detected any violation of the standard

rules. If it changed for red the the code or standard rules violation has been detected. The blue

color means that the entered parameter value is conditionally acceptable but may require special

agreement between the contracting parties or additional provisions in the inspection technique.

Because of obvious differences in the structure and content of European standards and ASMECode the techniques designing process is slightly different for each option. Due to this fact it will

be described separately for each standard option.

2.4.1. European standards

When developing radiographic techniques according to European standards the program displays

the following form where all designing steps may be executed.

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Fig. 6. Form for designing of radiographic techniques and calculation of exposure parameters.

In the form you should define all parameters of your radiographic technique going from top to

bottom.

In the radio group 'Object shape' define the tested object geometry. Select plate for all

plane parallel objects or pipe/tube for all objects with cylindrical geometry

In the combo box 'Material'select the material of the tested object . You can choose one

of the predefined materials (steel, nickel, cooper, titanium, aluminium) or one of the

additional materials you have entered to the program database

In the edit box 'External diameter, De'enter the external diameter of the tested pipe, tube

or cylindrical object. This field is inactivated for objects with plate geometry.

In the edit box 'Nominal thickness, t'enter the nominal wall thickness of the tested object.

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In the edit box 'Weld cap height, h'enter the estimated height of the weld cap when

testing welds. In other cases enter zero.

In the combo box 'Technique class to EN 444'select the radiographic technique class

required by the product standard or client specification.

In the combo box 'Test arrangement'select the test arrangement which will be used fortesting of cylindrical object (e.q. circumferential weld). The available options are based

on recommendations given in EN 1435. By clicking on the adjacent question mark button

you can get short info on restrictions imposed by the standard on exposure geometry.

In the combo box 'Gamma-ray source'select the source which will be used for the

planned examination. The sources available are those which have been entered to the

program database. By clicking on the adjacent question mark you can get short info on

penetrated thickness ranges acceptable for different gamma-ray sources.

After selection of the gamma-ray source the program will automatically calculate its

current activity and displays it in the adjacent 'Activity'field. You can manually overwrite

this value if you want to execute your examination on another day. In the edit box 'Source-to-film distance, SFD'enter the distance between gamma-ray

source and radiographic film assumed for the examination. By clicking on the adjacent

question mark button you can get precise information on the minimum SFD required by

the standard for the selected gamma-ray source, material thickness and radiographic

technique class.

In the radio group 'Film system class to EN 584-1'select the film system class which will

be used for the planned examination. To ease your choose, for each film class the symbol

of corresponding film type was given in parentheses. By clicking on the adjacent

question mark button you can get information on the standard requirements concerning

film system classes acceptable for a given examination. In the radio group 'Radiograph density'select the optical density for the central part of

your radiograph. The standard requirements concerning this parameter can be displayed

by clicking on the corresponding question mark button. When selecting density value

take into consideration that in some cases (e.q. in double wall, single image techniques)

radiograph density may be reduced near the film edges. You will be able to check this

condition at the final step of procedure development.

The option 'Use exposure correction for:'is activated only for those combinations of

gamma-ray source and film system class for which exposure correction data have been

entered to the program database. You can use one of the displayed correction options to

adjust the program calculation algorithm to the specific testing/processing conditions(film brand/type, material and thickness of metal screens, film processing mode). If none

of the displayed correction options is compatible with your technique select the 'no

correction'option to use the standard exposure calculation algorithm.

In the field 'Number of exposures on circumference'you should specify the number of

exposures required for testing the full circumference of a girth weld. The program

automatically calculates the minimum number of exposures required by EN 1435

standard but you can change this value if you have specific reasons. If you enter the

smaller value the program will indicate nonconformity. Normally you should leave this

value unaffected.

After entering all the above data click on the Calculate parametersbutton and the programcalculates several important parameters of your radiographic technique.

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Fig. 7. Parameters of radiographic technique calculated at the final step of technique

development.

In the 'Exposure time' field the program displays the exposure time required to obtain the

specified radiograph density at the film center.

In the field 'Density prediction on the film edges' the program displays radiograph density

prediction for the area near the film edges. Normally, except for the centric exposures, this value

will be lower than density specified for the film center. You should take care to keep this value

within the standard limits. Nonconforming values will be signaled by the program with a red

question mark on the adjacent button. In such a case you should modify your technique

parameters (i.e. radiograph density and/or number of exposures on circumference) and repeat the

calculation.

In the field 'Single film length' the program calculates the film length for a single exposure

compatible with the specified number of exposures for weld circumference. The calculated

values take into account the parallax effect near the film edges and additional 40 mm (1.5 in)

allowance for films overlap. You can make a practical use of this value for economical cutting of

film sections from a rollpack package.

In the panel 'Required IQI'the program displays the minimum IQI sensitivity values required by

the EN 1435 standard for the specified technique class and examination parameters. Depending

on the selected program option the numbers of wire type IQI or step-hole type IQI are displayed

in the corresponding fields for the 'source side'or/and 'film side' IQI values.

All parameters of the developed radiographic technique can be saved for printing by clicking on

the Save technique button. You can design and save several techniques in one program session.

All saved techniques can be reviewed by clicking on the View saved techniques button. The

subject of printing of the saved radiographic techniques is described in par. 2.5.

2.4.2. ASME Code

When developing radiographic techniques according to ASME Code, Section V the program

displays the following form where all designing steps may be executed.

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Fig. 8. Form for designing of radiographic techniques and calculation of exposure parameters.

In the form you should define all parameters of your radiographic technique going from top to

bottom.

In the radio group 'Object shape' define the tested object geometry. Select plate for all

plane parallel objects or pipe/tube for all objects with cylindrical geometry

In the combo box 'Material'select the material of the tested object . You can choose one

of the predefined materials (steel, nickel, cooper, titanium, aluminium) or one of the

additional materials which you have entered to the program database.

In the field 'Outer diameter, OD'enter the outer diameter of the tested pipe, tube or

cylindrical object. This field is inactivated for the objects with plate geometry.

In the field 'Nominal thickness, Tn'enter the nominal thickness of the tested object.

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In the edit box 'Weld reinforcement, h'enter the estimated height of weld reinforcement

when testing welds. In other cases enter zero.

In the combo box 'Exposure arrangement'select the source-weld-film arrangement

which will be used for testing of a circumferential weld. The available options and its

designations (A, B, C, etc.) are based on recommendations given inNonmandatory

Appendix A for ASME V, Article 2. By clicking on the adjacent question mark button youcan get short info on restrictions imposed by the Code on the exposure geometry.

In the combo box 'Gamma-ray source'select the source which will be used for the

planned examination. The sources available are those which have been entered to the

program database. By clicking on the adjacent question mark you get short info on

penetrated thickness ranges recommended for different gamma-ray sources. After

selection of the gamma-ray source the program will automatically calculate its current

activity and display it in the adjacent field 'Activity'. You can overwrite this value

manually if you plan to execute your examination on another day.

In the field 'Source-to-film distance, SFD'enter the distance between gamma-ray source

and radiographic film which will be used for the examination. By clicking on theadjacent question mark you can get information on the minimum SFD value required by

the Code for the selected gamma-ray source and material thickness. If you enter SFD

value not compatible with this condition the corresponding question mark becomes red.

In the radio group 'Film system class'choose the film system class (according to EN 584-

1) which will be used for the planned examination. To ease your choose, for each film

system class the symbol of popular film type belonging to this class was given in

parentheses. By clicking on the adjacent question mark button you can get short info on

preferable film system classes for the planned examination.

In the radio group 'Required film density'specify the radiograph density for the central

part of film. It should conform with the Code requirements which can be reviewed afterclicking on the adjacent question mark button. When selecting the density value take into

consideration that in some cases (e.q. for double-wall, single viewing techniques)

radiograph density may be reduced near the film edges. You will be able to check this

condition at the final step of procedure development.

The option 'Use exposure correction for:'is activated only for those combinations of

gamma-ray source and film system class for which exposure correction data have been

entered to the program database. You can use one of the displayed correction options to

adjust the program calculation algorithm to the specific testing/processing conditions

(film brand/type, material and thickness of metal screens and film processing mode). If

none of the displayed correction options is compatible with your technique select the 'nocorrection'option to use the standard exposure calculation algorithm.

In the field 'Number of exposures on weld circumference'you should specify the number

of exposures required for testing of the full circumference of a girth weld. The program

will automatically calculate the minimum number of exposures required by the Code but

you can change this value if you have specific reasons. If you enter there the smaller

value the program will indicate nonconformity. In most cases you should leave this value

unaffected.

After entering all the above data click on the Calculate parameters button to calculate several

important parameters of your radiographic technique.

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Fig. 9. Parameters of radiographic technique calculated at the final step of technique

development.

In the 'Exposure time' field the program displays the exposure time required to obtain the

specified radiograph density at the film center.

In the field 'Density prediction on the film edges' density prediction for the area near the film

edges is displayed. Normally, except for the centric exposures, this value will be lower than

density specified for the film center. You should take care to keep this value within the Code

limits. The nonconforming values will be signaled with a red question mark on the adjacent

button. In such a case you should modify the technique parameters (i.e. radiograph density

and/or the number of exposures on circumference) and repeat the calculation.

In the field 'Single film length' the program calculates the film length for a single exposurecompatible with the specified number of exposures for circumferential weld. The calculated

values take into account the parallax effect near the film edges and additional 40 mm (1.5 in)

allowance for films overlap. You can make a good practical use of this value for economical

cutting of film sections from a rollpack package.

In the panel 'Required IQI'the program displays the minimum IQI sensitivity required by the

Code for the specified examination parameters. Depending on the program options designations

of the hole type IQI and the essential hole or a wire type IQI and the essential wire are displayed

in the fields corresponding to the 'source side'and 'film side' IQI placement.

In the field 'Placement of location markers'the program will display the position of location

markers (film side or source side) required by the Code for the specified technique parameters.

All parameters of the developed radiographic technique can be saved for printing by clicking on

the Save technique button. You can design and save several techniques in one program session.

All saved techniques can be reviewed by clicking on the View saved techniques ... button. The

subject of printing of the saved radiographic techniques is described in par. 2.5.

2.5. Printing of radiographic techniques

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All radiographic techniques prepared and saved in Radiographic techniques designer can be

reviewed by clicking on the View saved techniques... button in the designer form. Each

technique is shown in one row of the displayed table with its parameters (tested material,

diameter, thickness, source, SFD etc.) displayed in the successive columns.

Fig. 10. Radiographic techniques saved in program memory and ready for printing.

In the above form you may review the saved techniques and decide which ones are to be printed.To delete a technique from the print list place the cursor on its row and click on the Delete

selected button.

After deleting all unwanted entries you may print out the remaining techniques by clicking on

the Print techniques button. The printouts contain all data and parameters necessary for

accurate techniques execution by qualified RT personnel. Two techniques are printed on one A4

page (see Fig. 11).

The techniques printouts can be handed to RT personnel going to the job reducing the

probability of exposure mistakes and enhancing the speed and quality of works performed by

radiographic crews. The other use of techniques printouts is documentation of executed works.

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Fig. 10. Printout of radiographic techniques prepared in line with EN 444/ EN 1435.

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Fig. 11. Printout of radiographic techniques prepared in line with ASME V.

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2.6. Calculation of activity timetables

During normal operation of the Gamex program users dont need gamma-ray sources activity

timetables because the program automatically calculates the current activity of selected sources.

Sometimes, however the users may wish to prepare and printout the source activity decay

timetable for documentation purpose or other reasons.

To calculate the activity timetable for gamma-ray source click on theActivity time-tables button

in the main window and execute the following steps in the opened form:

In the combo box Sourcechoose the gamma-ray source you want to calculate the activity

timetable for. The program will automatically fill in the fields: Source initial activityand

Date of initial activitywith data taken from its database.

In the combo box Activity time-table from choose the beginning date of the activity time-

table. The relevant end date will be automatically calculated depending on the selection made

in the Activity calculation stepsbox.

In the box 'Activity calculation steps'select the time step (days or weeks) of activity data

displayed in the timetable.

After filling in the above data click on the Calculate activity timetablebutton and the program

will calculate activity time-table for the selected source in defined period of time. Calculated

activities are expressed in [GBq] as well as in old units [Ci].

The picture of the relevant program form after executing the above steps is shown in the Fig. 12.

Fig. 12. Calculation of gamma-ray source activity timetable.

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The calculated activity time-table can be printed out by clicking on the Print activity time-table

button. The example printout is shown in Fig. 13.

Fig. 13. Example printout of gamma-ray source activity timetable.

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2.7. Calculation of radiation doses

The radiation safety standards specify the limits of radiation doses for personnel working with

radiation sources. The program can be helpful in implementation of radiation safety standards by

providing means for calculations of radiation doses received by testing personnel during work

with gamma-ray sources.

To perform dose calculations click on the Doses calculator button in the main window and

enter the following data in the opened form:

Fig. 14. Calculation of radiation doses received by testing personnel.

In combo box Gamma-ray sourceselect the source which will be used for making

exposures. The program automatically calculates the source current activity and displays

it in the field Source current activity [GBq].

In combo box Radiation shield materialselect material used as a radiation shield

protecting the operator from gamma radiation. You can choose between materials

commonly used for construction of radiation shields and collimators (steel, lead,

tungsten, concrete and sand ).

In edit box Radiation shield thicknessenter the thickness of radiation shield used by the

operator during exposure.

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In edit box Distance from the sourceenter the distance between the operator and the

gamma-ray source during exposure.

In edit box Radiation exposure time [min]enter the time the operator is exposed to

radiation.

After filling in the above data click on the Calculate dosebutton to calculate the received dose

equivalent expressed in milisieverts [mSv]. Note that the calculation results are only approximate

estimations of actually received doses and can not be treated as replacement of dose rate

measurements or personal dose monitoring systems required by the national radiation safety

standards.

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3. Advanced features

3.1. Exposure correction system

The common weakness of conventional exposure calculation tools (exposure charts, sliding

rulers, calculator programs etc.) is fact that they implement fixed computing algorithm which

does not take into account all factors affecting the radiograph density in real conditions. The

working/processing conditions are not the same in every radiographic laboratory. They may

differ in brand/types of films, thickness of Pb screens, type and mode of film processing, brand

of chemicals etc. All this factors may cause differences between calculated and actually obtained

radiographs densities even if all exposure parameters (SFD, material thickness, source activity)

have been correctly accounted for.

To resolve this problem radiographers often determine so called correction factors which areused to multiply the exposure times calculated with the exposure calculation tools. Correction

factors are established on the basis of test radiographs by comparison of their planned and

actually obtained densities.

This approach works reasonably well when testing conditions in a given lab are much the same

for all jobs. When the laboratory uses multiple types of sources, brands/types of films and

chemical processing methods it is necessary to determine several correction factors and use them

in a consistent way. In practice it often leads to mistakes in exposure calculations resulting in

badly exposed radiographs.

To overcome this difficulty a special exposure correction system was implemented in the Gamexprogram. It allows for adjusting the program calculation algorithms for virtually every

combination of testing/processing conditions which may occur in industrial radiographic

laboratory.

The basic principle of the implemented correction system is the same as with manual

calculations of correction factors. For every useful combination of testing/processing conditions

you make a test radiograph with exposure time calculated by the program in the standard mode

(without correction). Then you measure the test radiograph density and introduce it to the

program database together with the planned density and other parameters of the test exposure.

Having such correction data in its database the program automatically determines correctiondatasets matching to the particular testing conditions and propose to the user as exposure

correction options. The final decision on the use of a correction factor is always left to the user.

He can select one of the available options or choose the standard algorithm without correction.

Correction factors are calculated on the bases of film characteristic curves stored in the program

memory.

3.2. Correction data and test radiographs

The test radiographs are executed to obtain data neccesary for calculation of correction factors

for exposure calculation algorithm implemented in the Gamex program. Each test radiographshould represent one set of testing/processing conditions used in the laboratory. The significant

variables in this case are: source type, film brand/type, screens material and thickness and

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chemical processing. For every practical combination of these variables one test radiograph

should be executed. The basic rules of preparation of test radiographs are listed below:

The test radiographs should be made on carbon steel plates. The thickness of the selected

plate should be compatible with the used isotope. The exact value of the plate thickness

should be measured, for example using a caliper gage. The exposure time and other parameters for the test exposure should be calculated with

the Gamex program using its standard calculation mode (no corrections). The target

density for the test radiograph should be 2.5. The prescribed source-to-film distance, SFD

shoulds be 500 mm (20") or more to avoid problems with precise control of too short

exposure times.

The test radiograph should be executed in carefully controlled testing conditions with

exact adjustment of SFD and precise control of exposure time. The film packet should be

well protected from the back scattered radiation.

The test radiograph should be developed in well defined conditions (processor model,

processing mode, chemicals used) and its density measured with the calibrated

densitometer. The radiograph density should be measured in the central part of the filmwhere penetrated material thickness was equal to the measured plate thickness.

The test radiograph density together with all parameters of the test exposure should be

recorded and entered to the program database as described below

To explain how to enter exposure correction data to the program database we consider an

example test radiograph executed in the following conditions.

The steel plate of 20 mm thick was shot with a Ir-192 gamma-ray source on radiographic film

T200 belonging to C4 film system class. Lead screens, front and rear, of 0.025 mm thick were

used. Exposure time for SFD=500 mm and density Dp=2.5 had been calculated using standard

exposure calculation mode (no correction).

After exposure the film was processed in automatic processor using 8 min/30C processing cycle

and G135 developer. The film density was measured and found to be Do=2.03 i.e. lower then

expected.

To enter the test radiograph data to the program database click on the Exposure corrections

button in the main window and open the form titled Test radiographs data. The form displays

table of correction data already stored in the program database (see Fig. 15).

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Fig. 15. Table of test radiographs data used for calculation of exposure correction factors.

To add a new correction dataset click on theNew data button and open the form displayed in

Fig. 16. In the form enter the following data:

In the combo box 'Radionuclide' select the type of gamma-ray source which was usedfor making the test radiographs in this case: Ir-192

In combo box 'Film system class'select the film system class used for making the the test

radiograhs in this case: C4

In edit box 'Film brand/type'enter the specific brand/type of radiographic films used for

making the test radiographs in this case: Film T200

In combo box 'Metal screens material'select the material of applied metal screens in

this case Pb

In edit box 'Front screen thick.'enter the thickness of the front metal screen in this

case: 0.027

In edit box 'Back screen thick.'enter the thickness of the back metal screen in this case:

0.027

In edit box 'Film processing'shortly describe the type and parameters (time, temperature)

of test radiographs chemical processing in this case: Auto 30/8 G135

In edit box 'Test radiograph optical density - planned'enter the optical density planned

for the test radiographs when calculating the exposure time in the standard mode in this

case: 2.5

In edit box 'Test radiograph optical density - obtained'enter the optical density measured

in the central part of test radiographs in this case: 2.03

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Fig. 16. Program form for entering correction data from executed test radiograph.

To introduce the entered data to the correction data table click on the OKbutton and find them in

the last row of the table displayed in the Fig. 15. Then, to save the updated correction table in

the program database click on the OKbutton the 'Test radiographs data'form. Now the program

has the information necessary for calculation of exposure correction factors for the testing

conditions specified in our example.

In the same way you can enter correction data corresponding to every combination of

testing/processing conditions used in your laboratory. The information is permamently stored in

the program database and can be used by the program in subsequent exposure calculations for

similar testing/processing conditions.

3.3. Using of exposure correction system

Using of exposure correction system is ilustrated in Fig. 17. When developing radiographic

technique in technique designer you have to define the gamma-ray source and the film system

class. After these data are entered the program checks its database for the correction data

matching this testing conditions (i.e. type of source and film class). If matching entries are found

they are displayed as options of the combo box 'Use exposure correction for:' (see Fig. 17).

Now the user must select the option best suited to the actual testing and processing conditions.

He should choose the correction matching the film type, metal screen thicknesses and processingconditions. In none of the displayed options match the actual testing conditions simply select 'no

correction'option to use the standard calculation algorithm.

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In the example given in Fig. 17 the program found in its database one correction dataset relevant

to Ir-192 gamma-ray source and C4 film system class. It is specifically valid for film T200 used

with Pb screens 0,027 mm thick and developed in automatic processor working in 30C/ 8min

cycle and using G135 developer.

Fig. 17. Selection of exposure correction option.

After choosing the relevant correction option the program will automatically calculate its

exposure correction factor and use it in the subsequent calculation of exposure time. The applied

correction factor will be clearly indicated on the technique printout together with the numerical

value of the correction factor applied by the program in the exposure time calculations.

The option 'Use exposure correction for:' will be active only for those combinations of source

type and film system class for which corresponding correction data have been introduced to theprogram database. For maximum accuracy of program calculations test radiographs should be

executed for all practical combinations of testing/processing conditions used in the laboratory. In

case of substantial changes in working conditions (e.q. introducing of new film type, changing

processing conditions etc.) new test radiographs should be executed and updated correction data

entered to the program.

3.4. Testing materials other than steel

Basic exposure calculations are performed for steel which is the most commonly tested material.

When items made of other materials are to be tested the so called radiographic equivalence

factors are used for conversion of actual material thickness to the equivalent thickness of steel.

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The exact values of radiographic equivalence factors for a given material depend on the energy

of radiation. For high energy gamma-ray sources considered in this program this dependence

may be neglected and a single value of radiographic equivalence factor may be assumed for all

three isotopes.

The approximate values ofradiographic equivalence factors for commonly tested materials aretabulated in handbooks on industrial radiography. On that bases equivalence factors for Nickel,

Copper, Titanium and Aluminium were predefined in the Gamex program. They can be

displayed on the screen by clicking on theMaterial factors button in the main window.

Fig. 18. Table of tested materials with radiographic equivalence factors.

For testing other materials the user should determine radiographic equivalence factors on its

own. To enter the equivalence factor for a new material to the program database click on the

Materials button in the main window and in the opened form click on theNew data button.

In the form 'Entering new material', shown in Fig. 19, enter the following data:

In edit box 'Material'enter the material name or symbol

In edit box 'Radiographic equivalence factor'enter the value of radiographic

equivalence factor determined for this material

Click on the OKbutton to introduce the new material to the materials table and then once more

OKbutton to save the updated table to the program database. From now on you can prepare

radiographic techniques for items made of this material. You can just select it from the list of

materials displayed in the combo box 'Material' in the techniques designer (see Fig. 20).

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Fig. 19. Entering the radiographic equivalence factor for a new material.

Fig. 20. Technique designer with new material CuNi30Fe available for testing.

Date post:	03-Apr-2018
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