IMAGE QUALITY INDICATOR (IQI) OR PENETRAMETER
SELECTION FOR INDUSTRIAL RADIOGRAPHY
WIRE-TYPE IQI
WIRE-TYPE IQI
How to select the penetrameter (IQI) for radiography? Or How to ensure that proper sensitivity is there on the radiography film?
IQI in radiography is based on referencing code or standard. IQI radiography assures that proper quality of radiography film is obtained.
IQI or Penetrameter is used to ensure that
the minimum required sensitivity is there on the radiography film.
What is sensitivity?
Sensitivity of a radiography film is the
minimum size of discontinuity that can be detected in that radiography
film.
How we will ensure that the required
sensitivity is there on the radiography film?
This is done by using IQI or Penetrameter
Most of the codes and specification asks
for a minimum sensitivity of 2%.
In the below example you will understand
what is mean by 2% sensitivity or we can say IQI selection formula.
Example - 1:
You have to radiograph a plate to
plate welded joint of 8mm thickness. The specification asks for 2% sensitivity.
Now 2% of 8mm=0.16mm.
So in the
radiography film a discontinuity of size from 0.16mm should be visible. In
other words, at least the discontinuity starting from the size of 0.16mm should
be visible. In other words the minimum size of the discontinuity that should be
visible in the radiography film is of 0.16mm.
Now how will you measure that the
radiography film is having minimum 2% sensitivity. We have to use the
'instrument' called IQI or Penetrameter.
IQI is a set of standard wires having
standard diameter.(Hole type IQI is also used. In that case it will be standard thickness plates with standard diameter holes).
The IQI is placed on a radiography film while doing the
radiography. The image will be caught in the film. If the wire having
0.16mm diameter is visible in the radiography film, then we can say that the
film is having a sensitivity of this 2%.
The IQI that is commonly used is of ASTM and
DIN standards.
We will discuss about how the IQI is selected based on ASTM standard.
Below table (Table 233 T-233.2 in ASME BPVC Sec V) is the set of ASTM wire type
IQI with its wire diameters.
Now to our above example, select the set
of IQI to be used. How this is done?
What is the minimum size of wire to be shown in our radiography film in our example?
It is of 0.16mm.
Select the set of wire having 0.16mm dia wire.
It is in 'set A' in the above table and the wire is having a identity number of 4. So use this set at the time of taking radiography and if that wire is visible (3 wires minimum will be visible that is wire of thickness 0.16mm, 0.2mm and 0.25mm will be visible) in the film, then that radiography film is said to be of having 2% sensitivity.
Example 2:
Radiography to be done on a plate with thickness of 32mm with a minimum sensitivity of 2%.
Now the 2% of 32 that is 32 x 2/100=0.64mm
Select the set having a wire of 0.64mm thickness from the table given above. It is set B and wire identity number is 10.
If in the radiography film of the above 32mm thickness plate, the wire with identity number 10 is visible, we can say that the radiography film is having 2% sensitivity.
Radiography to be done on a plate with thickness of 32mm with a minimum sensitivity of 2%.
Now the 2% of 32 that is 32 x 2/100=0.64mm
Select the set having a wire of 0.64mm thickness from the table given above. It is set B and wire identity number is 10.
If in the radiography film of the above 32mm thickness plate, the wire with identity number 10 is visible, we can say that the radiography film is having 2% sensitivity.
Now do the reverse process to find out
what is the sensitivity of a radiography film.
We have taken the radiography of a 60mm
thickness plate and in the radiography film used set C and the wire with identity number up to 12 is visible (5 wires will be visible in this radiography film). What is the sensitivity?
Find the diameter of the wire having identity number 12.
From the table, it is 1.02mm.
Sensitivity =
Diameter of the smallest IQI wire visible x 100 / Thickness of the plate radiographed.
So in the above case, Sensitivity = 1.02 X 100 / 60 = 1.7%
So the sensitivity is higher than that is required and the radiography film is acceptable from sensitivity point of view.
The 2% sensitivity is an old method or we can say that a thumb rule for calculating sensitivity. ASME BPVC Section 5 specifies the wire identity number that shall be minimum visible while taking radiography of material with minimum thickness range as in the below table (IQI selection chart).
Please note an interesting fact in this. Up to and including 6.4 mm thickness the IQI identity number that shall be visible is 5 for source side and 4 for film side.
The other important point to note in the IQI selection is that the IQI shall be made up of the same material as that of the material to be radiographed or the IQI shall be of a radiographically similar material.
In general, in most cases, film side radiography is done due to practicality in doing the settings for radiography.
Recommended Further Reading: Hole-Type IQI
excellent explanation ..
ReplyDeleteThank You; Please suggest topics that you are interested to see in this blog.
DeleteNice sir very good
DeleteSensitivity : EWth 10th and VWth 9th , what does it mean !? please consider 32mm plate.
ReplyDeletePlease give some more detailed explanation to your question.
DeleteYou can refer table T-276 for IQI selection and in the case of 32mm plate, on source side essential wire of 10 must be seen.
when the VW is 9 means (Refer table T233.2, given above):
Deletethe diameter of the wire is 0.51mm that means the film have the sensitivity to show the defects of 0.51mm and higher size.
when VW is 10 means: the diameter of the wire is 0.64mm that is you can see defects of 0.64mm and higher size.
So EW is 10 and VW is 10 means the radiographic image is having more sensitivity than required (based on the condition what you have mentioned.)
Hope this became clear to you
Please feel free to ask if not clarified.
Thank You
This is very much Helpful, thank you
DeleteThank you
DeleteExcellent information pls let me know about hole type can you explain...and other one how to select the film for radiography fine or coarse grain
ReplyDeletehttp://hareeshkv.blogspot.com/2017/03/hole-type-iqi-penetrameter-selection-in.html
Deletevery helpful tips....thank you sir
ReplyDeleteThank You
DeleteOne thing I am struggling to find documentation on is the visibility of the complete wire running through the parent material and the weld. Does the entire wire from top to bottom need to be clearly visible? Sometimes depending on the weld profile. Small parts of the wire aren’t clear.
ReplyDeleteRegards and thanks
If the code followed for radiogrpahy testing is ASME BPVC Sec V, Please refer Table T-276 in the code.
DeleteNo need that all the wires are to be visible. If the wire mentioned in the code is visible the sensitivity can be accepted.
Can any one explain ir-192 50ci source,Dia 1inch 3.38mm thick, I give 65cm sfd but the sensitivity is not achievable(required wire 13) we have only ir192 source, can any one explain, I need a proper details
ReplyDeleteDo it with a low curie source or Se-75 or with X-ray. Getting a sensitivity on a 3.38mm with 50Ci is practically a difficult task. Try with small grain size film such as AGFA structurix D2 with 50Ci
DeleteIf at some locations (along the length of the wire) if it is not seen means the thickness at that location is more than what is calculated for the IQI selection.
ReplyDeletewhat about DWDI film sensitivity, what is the calculation of the thickness? 1 t or 2 t?
ReplyDeleteRefer TableT-276 of ASME BPVC Sec V; the thickness is given as Nominal Single wall Material Thickness range for the selection of minimum IQI thickness requirement in film side. So In DWSI, Single wall thickness is to be considered.
Deleteits quiet interesting for me, u explain very meaningfully.
ReplyDeletethanks
Thank you
Deletepipe thickness 2.77mm but IQI used ASTM 1A but rt level 3 not accepted any issue
ReplyDeleteCheck your client procedure may be use din pentameter
DeleteIQI's are available based on different standard's like ASTM, DIN etc. The project specification may contain such information or we should clear it before starting the radiography process.
DeleteIf it is not specifically mentioned we can use the wire standard of ASTM if the code for radiography is ASME BPVC Sec V.
The reason for rejection should be given in writing as an ethical standard in radiography film viewing.
Many times it is seen that inspectors are asking for DIN wires and not even ready to review a film with ASTM wires. One of the reason for selecting the DIN wire is the set of DIN wire contains 7 wires as compared to 6 wires in a ASTM set. So range of visibility of wires will be more. But it is not a good logic or practice. If the wire visible is as per the requirements one can accept the sensitivity.
Thank you for reading my blog
If IQI is kept in Source side essential wire of 5 (0.2mm) and if kept in film side essential wire of 4 (0.16) has to be seen. If it is visible then it should be accepted. Rejection clarification has to be sought from RT Level 3 . Please also refer T-276.2 (a) of ASME BPVC Sec V Article 2. The reinforcement (as per referencing code section) should also be considered while calculating the thickness that means in your case it will be 2.77mm plus the allowed reinforcement as per the referencing code(eg.ASME B31.3)
ReplyDeletewhich means weld reinforcement need to be added into the plate thickness? for example. let say if the plate is 12mm and the reinforcement is 2.5mm. so the total thickness for IQi selection is based on 14.5mm(12mm+2.5mm)?
ReplyDeleteThe reinforcement is to be added. But the reinforcement thickness is to be as per the code which the welding is done and not on actual measurement of reinforcement.
DeleteReinforcement shall be inside and our side of joint as per code specified...
DeleteEg.12+3+3=18 mm thickness have to be consider during selection of IQI..
Agree, if the referencing code specifies an inside reinforcement we can consider it otherwise we cannot consider it.
DeleteThank you for the explanation.
ReplyDeleteThank you for reading my blog.
DeleteThank you very much
ReplyDeleteThank you for reading my blog
DeleteHi there ,
ReplyDeletehow to select the hole type penetrameter baesd on 2-2t ? example 10 mmm pipe which hole type need to select based on 2-2T ?
Hope you will get clarity from the below post. If not please feel to comment with your doubts.
Deletehttps://hareeshkv.blogspot.com/2017/03/hole-type-iqi-penetrameter-selection-in.html
Thank you for reading my blog.
WHAT WILL BE THE SENSITIVITY OF A PIPE 18" SCH 100 ,SOURCE lr-192 ,strenght 15ci
ReplyDeleteWe cannot calculate the sensitivity based on the data that is given.
DeleteThe sensitivity requirements can be calculated based on Table T-276 of ASME BPVC Sec V.
Based on the thickness of pipe and information on Film side/Source side film setting process you can select the required sensitivity.
The thickness of a Sch 100, 18" pipe is 29.36mm. If it is source side, the essential wire is of number 10 and if it is of film side, the essential wire is of number 9 based on ASTM IQI wire set. If DIN standard wire set is used based on the diameters of the essential wire of ASTM set you can explain.
Please feel free to ask if your doubt is not cleared.
Please feel free to ask if your doubt is not cleared.
Thank sir
ReplyDeleteThank you for reading my blog.
DeleteGood explaination,helped me alot.
ReplyDeleteThank you for reading my blog
DeletePlease I need answer...
ReplyDeleteThe diameter of 1T hole clearly visible on a radiograph with equivalent sensitivity of 1.4% is 750 microns. The thickness of the job is??!
Sorry for the late replay. Please read my blog.
Deletehttps://hareeshkv.blogspot.com/2017/03/hole-type-iqi-penetrameter-selection-in.html
Simple and Very Clear way of teaching fundamentals of Radiography Testing . Thanks
ReplyDeleteThank you for your good words and thank you for reading my blog.
DeleteExcellent Sir
ReplyDeleteThank you for reading my blog
Deleteradiography performed as per asme code and acceptable of 2.77mm thickness pipe now we have to make it accept as per EN 1435 and EN 12517-1:2006 is it possible?
ReplyDeleteI didn't gone through the entire standards. I did not worked in these standards. In EN 1435 personnel qualification was not as per SNT-TC-1A, Permanent identification is needed on materials which are radiographed are seen. The IQI requirements are clearly given and hope you can easily compare the requirements. EN 12517-1:2006 is very clear in describing the discontinuity acceptance requirements. I hope you can easily make a comparison of both ASME and these standards. If my answer is not satisfying you, please replay. Meanwhile i will also try to make a comparison sheet (Be frank, it will take some time as i am now working on API 570 Study guide series in this blog, but sure will make it in a later date). If you have further queries please let me know. Thank you for reading my blog and writing to me. Regards, Hareesh K V
Deletehi ,
DeleteHOW TO SELECT A IQI FOR 2" PIPE , NEED TO CALCULATE SINGLE OR DOUBLE WALL PLUS RF ?
Please refer Clause T-276.2 (a) of ASME BPVC Section V. You will get a clear idea. It is Nominal Single-Wall material thickness plus RF. The requirement of RF is also given. Please read the clause for further details.
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Thank you it is very useful 😊
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DeleteThank you
Nice explanation plz explain source side and film side with example
ReplyDeleteThank you for your good words and thank you for reading my blog. Please like the facebook page for updates on this blog. https://www.facebook.com/MechConstEngineer/
DeleteThank you
We have taken the radiography of a 60mm thickness plate and in the radiography film used set C and the wire with identity number up to 12 is visible (5 wires will be visible in this radiography film). What is the sensitivity?
ReplyDeleteFind the diameter of the wire having identity number 12.
From the table, it is 1.02mm. ------------------>>>>2% of the plate thickness should be 1.2mm.?????
There is no hard and fast rule that we need a 2% sensitivity.
DeleteThe 60mm plate thickness and wire number 12 visibility was an example to show the reverse calculations. In that case sensitivity is 1.7% only and it is explained also.
Depends on the project requirements and construction code the sensitivity requirements may differ.
one doubt
Deletethickness :8mm
Astm 1A used
As per table essential wire is 5th n dia is 0.2
but 2% sensitivity means 0.16 its 4th wire
in film 5th is visible but not 4th, not meeting sensitivity req
can we accept or not?
Please note that there is no criteria called 2% sensitivity. Refer Table T-276 of ASME BPVC Sec V. It specifies the wire no. that should be visit for a particular thickness.
DeleteIn this case, as you mentioned, the 5th wire is visible means the sensitivity is acceptable.
No where in the code it is written that 2% sensitivity is needed.
Thank you for reading the blog.
Sensitivity, small wire or visible diameter does not indicate the size of the defect
ReplyDeleteJudging of defect size based on a wire diameter is a comparison method adopted in Radiography film reviewing.
DeleteIf a particular wire diameter is seen on the film means the sizes of defects in the weld joint/item radiographed from that diameter to higher than the diameter will be visible.
So indirectly by the judgement of sensitivity, it means that the defects of sizes from the wire diameter is visible on the radiography film.
Thank you for reading the blog
IQI – Image Quality Indicator – is a device for showing the quality of a radiograph. The quality of a radiograph determines the amount of detail that can be shown. Generally, the quality of a radiograph depends on three factors:
ReplyDeleteThe unsharpness or blurring of the image;
The contrast or change in density on an image for a known change in thickness in the specimen;
The noise on the image, eg the graininess of the film.
There is a difference of opinion to me for this comment.
DeleteThe three factors that are mentioned here are determined by three different methods and IQI is not a tool for judging all these three.
The unsharpness is calculated using the parameters F, D and d Based on clause T-274 in ASME BPVC Sec V
The density is determined by densitometer or step wedge comparison film.
The noise or grainess is determined during film selection. There are films available with different grain size. Select the proper film based on your requirement.
IQI is to measure sensitivity
All the above factors determine the 'Quality' of a radiograph.
There are other factors like film processing, film handling etc. which also affects the 'Quality' of a radiography film.
Thank you for reading my blog.
if the material thickness is difference, how to choose the IQI?
ReplyDeleteexample joint thickness is 12.7 mm to 19.05 mm
anyone can explain please
according to minimum thickness
DeleteThank you
ReplyDeleteDWDI , iqi /sensitivity calcultion formula , conflict between European and ASME V
ReplyDeleteAs per Section V , wall thickness+RF
But many European standards are saying Double wall thickness
May I know in which European standard it is mentioned?
DeleteIf I'm getting minimum size of wire dia is 0.25mm, which set should I use SET A OR SET B.?
ReplyDeleteYou can use SET A or SET B as per Table T-233.2 of ASME BPVC SEC V. My suggestion is to use SET A because it will show more than one wire if your sensitivity is good.
Deletethe minimum how much wire lenth can be visible in the radiography film as per sec V
ReplyDeleteIs it the wire length or wire identity number? Regarding wire length, it is not mentioned in the code. Regarding which wire is to be seen - Please refer Table T-276 ; IQI Selection in ASME BPVC Section V.
DeleteSuperbly Explained, i am clear with the basics.
ReplyDelete