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01:52 Sep-10-2005
Kaveh Edalati
IQI selection in double wall radiography of pipes

Dear friends and colleagues

In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
1- Single wall thickness
2- Double wall thickness
I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
My email is edalatik@yahoo.com.au

Thank you


 
02:37 Sep-11-2005
Ed T.
Re: IQI selection in double wall radiography of pipes ----------- Start Original Message -----------
: Dear friends and colleagues
: In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
: 1- Single wall thickness
: 2- Double wall thickness
: I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
: I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
: My email is edalatik@yahoo.com.au
: Thank you
------------ End Original Message ------------

IQI selection is based on "Single Wall thickness and maximum reinforcement allowed by the referencing code section". This is true regardless of the technique being used.



 
09:50 Sep-11-2005

Juan Amado

Engineering, Inspection
Arco Industrial, S.A.,
Panama,
Joined Nov 2001
44
Re: IQI selection in double wall radiography of pipes Dear colleague:

In the evaluation of welds utilizing radiography, the double wall technique offers a great practical advantage, but is not without its downside. Although a given source we may have the energy to go through both sides of the pipe in a single exposure (be it that we might want to evaluate both sides of the weld in the same film as in double exposure double side viewing, or that we only want to evaluate one side as in double exposure single side viewing), we must fine tune our technique to be able to discern details in the subject under investigation, which in both cases is "a single weld bead". This is why the choice for the diameter of the IQI wire penetrameters is based on the single side thickness plus the allowed reinforcement. Complying with this requirement will yield a radiographic image that is focused enough to allow us to see the right amount of detail on one of the weld beads.

The fallouts from this technique are the following:

1. For "Double Exposure - Single Side" viewing, the thickness that the radiation must go through is equal to: side of interest + weld reinforcement + near side of the pipe. In this case we are no interested in examining any of the metal in the near side of the pipe (near meaning closer to the source), so we only need to take this metal thickness into account in our time calculation for the exposure, so that we may achieve the required film density. Of course there is some unsharpness factor associated with the radiation going through that first face of the pipe, mainly related to scattering and dispersion mechanisms, but in practice this effect is found to be either negligible or easily corrected for by adding additional distance (usually in the order of 20 mm to 50 mm for most pipe) to our shot

2. For Double Exposure-Double Side viewing, the thickness that the radiation must go through is the same as in the prior case, but in this case we are interested in looking at the weld bead on both, the near side as well as the far side (far meaning in contact with film) of the pipe.
Based on the formula for geometric unsharpness, Ug=Fd/D, where
Ug = Geometric Unsharpness
F = Focal size of the source (the largest linear dimension of the source)
d = Distance from the source side of the specimen to the film side of the specimen (Example: For a 2" Schedule 40 pipe with external diameter of 2.38", it would be wise to use this dimension plus a weld reinforcement of 0.125" on each side for a total of 2.63")
D = Distance from the source to the surface of part being tested

Knowing that we want to keep this factor Ug ¡Ü 0.02, we can see that even though the thickness of the pipe would normally only be 0.154", we need to use 2.63" for our "d" in the Ug calculation, yielding a much longer distance for the shot, and hence a longer exposure time.

I hope this helps
Juan Amado

----------- Start Original Message -----------
: Dear friends and colleagues
: In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
: 1- Single wall thickness
: 2- Double wall thickness
: I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
: I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
: My email is edalatik@yahoo.com.au
: Thank you
------------ End Original Message ------------




 
01:13 Sep-12-2005
Ed T.
Re: IQI selection in double wall radiography of pipes ----------- Start Original Message -----------
: Dear colleague:
: In the evaluation of welds utilizing radiography, the double wall technique offers a great practical advantage, but is not without its downside. Although a given source we may have the energy to go through both sides of the pipe in a single exposure (be it that we might want to evaluate both sides of the weld in the same film as in double exposure double side viewing, or that we only want to evaluate one side as in double exposure single side viewing), we must fine tune our technique to be able to discern details in the subject under investigation, which in both cases is "a single weld bead". This is why the choice for the diameter of the IQI wire penetrameters is based on the single side thickness plus the allowed reinforcement. Complying with this requirement will yield a radiographic image that is focused enough to allow us to see the right amount of detail on one of the weld beads.
: The fallouts from this technique are the following:
: 1. For "Double Exposure - Single Side" viewing, the thickness that the radiation must go through is equal to: side of interest + weld reinforcement + near side of the pipe. In this case we are no interested in examining any of the metal in the near side of the pipe (near meaning closer to the source), so we only need to take this metal thickness into account in our time calculation for the exposure, so that we may achieve the required film density. Of course there is some unsharpness factor associated with the radiation going through that first face of the pipe, mainly related to scattering and dispersion mechanisms, but in practice this effect is found to be either negligible or easily corrected for by adding additional distance (usually in the order of 20 mm to 50 mm for most pipe) to our shot
: 2. For Double Exposure-Double Side viewing, the thickness that the radiation must go through is the same as in the prior case, but in this case we are interested in looking at the weld bead on both,the near side as well as the far side (far meaning in contact with film) of the pipe.
: Based on the formula for geometric unsharpness, Ug=Fd/D, where
: Ug = Geometric Unsharpness
: F = Focal size of the source (the largest linear dimension of the source)
: d = Distance from the source side of the specimen to the film side of the specimen (Example: For a 2" Schedule 40 pipe with external diameter of 2.38", it would be wise to use this dimension plus a weld reinforcement of 0.125" on each side for a total of 2.63")
: D = Distance from the source to the surface of part being tested
: Knowing that we want to keep this factor Ug ¡Ü 0.02, we can see that even though the thickness of the pipe would normally only be 0.154", we need to use 2.63" for our "d" in the Ug calculation, yielding a much longer distance for the shot, and hence a longer exposure time.
: I hope this helps
: Juan Amado
:
: : Dear friends and colleagues
: : In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
: : 1- Single wall thickness
: : 2- Double wall thickness
: : I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
: : I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
: : My email is edalatik@yahoo.com.au
: : Thank you
------------ End Original Message ------------
Yes but the IQI selection is based on the nominal single wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing code section. Backing rings or strips shall not be considered as part of the weld thickness. That is the key word. "Weld thickness". Your sensitivity must be based on the weld thickness. This ensures you are able to locate defects of a certain size in relation to your weld thickness. See ASME Section V, Article 2, T-276.2.

This is regardless of whether you are using a single wall technique or double wall technique.

Even if you are exposing and viewing a superimposed technique, you must still be able to discern a flaw of a size that is within a range of the percentage of the wall thickness.

For example, if you are required to be able to discern a flaw that is 2% of the thickness and you use double wall as your basis for IQI selection, you now just gave yourself 4%instead of 2%. Sensitivity must be based on your part thickness.




 
05:07 Sep-12-2005
Kaveh Edalati
Re: IQI selection in double wall radiography of pipes ----------- Start Original Message -----------
: Dear colleague:
: In the evaluation of welds utilizing radiography, the double wall technique offers a great practical advantage, but is not without its downside. Although a given source we may have the energy to go through both sides of the pipe in a single exposure (be it that we might want to evaluate both sides of the weld in the same film as in double exposure double side viewing, or that we only want to evaluate one side as in double exposure single side viewing), we must fine tune our technique to be able to discern details in the subject under investigation, which in both cases is "a single weld bead". This is why the choice for the diameter of the IQI wire penetrameters is based on the single side thickness plus the allowed reinforcement. Complying with this requirement will yield a radiographic image that is focused enough to allow us to see the right amount of detail on one of the weld beads.
: The fallouts from this technique are the following:
: 1. For "Double Exposure - Single Side" viewing, the thickness that the radiation must go through is equal to: side of interest + weld reinforcement + near side of the pipe. In this case we are no interested in examining any of the metal in the near side of the pipe (near meaning closer to the source), so we only need to take this metal thickness into account in our time calculation for the exposure, so that we may achieve the required film density. Of course there is some unsharpness factor associated with the radiation going through that first face of the pipe, mainly related to scattering and dispersion mechanisms, but in practice this effect is found to be either negligible or easily corrected for by adding additional distance (usually in the order of 20 mm to 50 mm for most pipe) to our shot
: 2. For Double Exposure-Double Side viewing, the thickness that the radiation must go through is the same as in the prior case, but in this case we are interested in looking at the weld bead on both,the near side as well as the far side (far meaning in contact with film) of the pipe.
: Based on the formula for geometric unsharpness, Ug=Fd/D, where
: Ug = Geometric Unsharpness
: F = Focal size of the source (the largest linear dimension of the source)
: d = Distance from the source side of the specimen to the film side of the specimen (Example: For a 2" Schedule 40 pipe with external diameter of 2.38", it would be wise to use this dimension plus a weld reinforcement of 0.125" on each side for a total of 2.63")
: D = Distance from the source to the surface of part being tested
: Knowing that we want to keep this factor Ug ¡Ü 0.02, we can see that even though the thickness of the pipe would normally only be 0.154", we need to use 2.63" for our "d" in the Ug calculation, yielding a much longer distance for the shot, and hence a longer exposure time.
: I hope this helps
: Juan Amado
:
: : Dear friends and colleagues
: : In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
: : 1- Single wall thickness
: : 2- Double wall thickness
: : I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
: : I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
: : My email is edalatik@yahoo.com.au
: : Thank you
------------ End Original Message ------------

Dear Juan
thank you very much. Logically, single wall thickness should be used for sensitivity calculation. Sensitivity must be based on single thickness, regardless to exposing technique. But practically, obtaining this sensetivity is impossible in many causes. We need to use X-ray or D4 or MX-125 films or we need to decrease ug.
If standard suggest s=0.02 based on single wall thickness, ug, sfd, film type source type should be re-defined.
What is your experince in this cause. Can you obtain s=0.02 based on single wall thickness easily.

Ragards
Kaveh



 
07:10 Sep-12-2005
Kaveh Edalati
Re: IQI selection in double wall radiography of pipes ----------- Start Original Message -----------
: : Dear friends and colleagues
: : In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
: : 1- Single wall thickness
: : 2- Double wall thickness
: : I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
: : I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
: : My email is edalatik@yahoo.com.au
: : Thank you
: IQI selection is based on "Single Wall thickness and maximum reinforcement allowed by the referencing code section". This is true regardless of the technique being used.
------------ End Original Message ------------

Dear Juan
thank you very much. Logically, single wall thickness should be used for sensitivity calculation. Sensitivity must be based on single thickness, regardless to exposing technique. But practically, obtaining this sensetivity is impossible in many causes. We need to use X-ray or D4 or MX-125 films or we need to decrease ug.
If standard suggest s=0.02 based on single wall thickness, ug, sfd, film type source type should be re-defined.
What is your experince in this cause. Can you obtain s=0.02 based on single wall thickness easily.

Ragards
Kaveh



 
01:13 Sep-12-2005
George Buddy Butcher
Re: IQI selection in double wall radiography of pipes ----------- Start Original Message -----------
: Dear friends and colleagues
: In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
: 1- Single wall thickness
: 2- Double wall thickness
: I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
: I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
: My email is edalatik@yahoo.com.au
: Thank you
------------ End Original Message ------------

Typically in the USA, based on most all, if not all code requirements, IQI selection is based on the weld single wall thickness, plus allowable weld reinforcement, as stated by others in this forum. Total weld reinforcement usually includes both weld sides.

In the absence of a required reference standard or code, you should contact your customer or QC/NDT manager (or both) and work together to develop an acceptable procedure that outlines all inspection and acceptance parameters.

Hope this helps some.



 
06:13 Sep-13-2005

Juan Amado

Engineering, Inspection
Arco Industrial, S.A.,
Panama,
Joined Nov 2001
44
Re: IQI selection in double wall radiography of pipes Based on my experience and study, I'll address the role and interaction of some of the variables in the RT process.
1. Geometric Unsharpness: It is always possible to achieve a Ug of less than 0.02, if you have enough physical distance to set your shot in. Since Ug=Fd/D then by basic algebra we can set our equation to be D=Fd/Ug, setting Ug to 0.02 will give D=Fd/0.02
Any increase in the distance resulting from this equation will yield a Ug less than 0.02, and hence a more focused picture, from the geometric stand point. The main compromise with this solution is that the time of the shot increases, but as with any solution there is some degree of compromise.
2. Fine grain film (D4): One thing to keep in mind when choosing a fine (or finer) grain film is that a very fine grain film by itself is not capable of focusing the image of the shot. If the image is focused by nature of it geometry, the a finer grain film will be able to give you more detail, but if the image in out of focus, or has blurrededges, the what you will get is more detailed blurriness. You can't make the picture more focused by adding a higher resolution film!
3. Source size and shape: The only additional trick that I can give has to do with the geometric shape of the source itself. Ir 192 sources are made of wafers stacked one on top of another to reach the desired activity (Usually 100 Ci) This arrangement creates a cylinder with rough dimensions of 1/8" diameter by 1/8" length. The focal spot size for such a source is given by the largest dimension you can find on that given cylinder, which would be a diagonal between the opposite parallel sides of the cylinder (It is much easier to explain with a picture). For such an arrangement the focal spot size would be 0.177". This measurement has an effect on the Ug yielding a larger stand off distance. Now if you take the necessary precautions, and have the end of the cylinder be your source, that is, if you use the end of the source and point it straight into the shot, the actual focal spot is reduced (0.125" which is the round face of the cylinder), and you end up with a more focused shot at a slightly closer distance.

Hope this helps,
Juan Amado


----------- Start Original Message -----------
: : Dear colleague:
: : In the evaluation of welds utilizing radiography, the double wall technique offers a great practical advantage, but is not without its downside. Although a given source we may have the energy to go through both sides of the pipe in a single exposure (be it that we might want to evaluate both sides of the weld in the same film as in double exposure double side viewing, or that we only want to evaluate one side as in double exposure single side viewing), we must fine tune our technique to be able to discern details in the subject under investigation, which in both cases is "a single weld bead". This is why the choice for the diameter of the IQI wire penetrameters is based on the single side thickness plus the allowed reinforcement. Complying with this requirement will yield a radiographic image that is focused enough to allow us to see the right amount of detail on one of the weld beads.
: : The fallouts from this technique are the following:
: : 1. For "Double Exposure - Single Side" viewing, the thickness that the radiation must go through is equal to: side of interest + weld reinforcement + near side of the pipe. In this case we are no interested in examining any of the metal in the near side of the pipe (near meaning closer to the source), so we only need to take this metal thickness into account in our time calculation for the exposure, so that we may achieve the required film density. Of course there is some unsharpness factor associated with the radiation going through that first face of the pipe, mainly related to scattering and dispersion mechanisms, but in practice this effect is found to be either negligible or easily corrected for by adding additional distance (usually in the order of 20 mm to 50 mm for most pipe) to our shot
: : 2. For Double Exposure-Double Side viewing, the thickness that the radiation must go through is the same as in the prior case, but in this case we are interested in looking at the weld bead on both, the near side as well as the far side (far meaning in contact with film) of the pipe.
: : Based on the formula for geometric unsharpness, Ug=Fd/D, where
: : Ug = Geometric Unsharpness
: : F = Focal size of the source (the largest linear dimension of the source)
: : d = Distance from the source side of the specimen to the film side of the specimen (Example: For a 2" Schedule 40 pipe with external diameter of 2.38", it would be wise to use this dimension plus a weld reinforcement of 0.125" on each side for a total of 2.63")
: : D = Distance from the source to the surface of part being tested
: : Knowing that we want to keep this factor Ug ¡Ü 0.02, we can see that even though the thickness of the pipe would normally only be 0.154", we need to use 2.63" for our "d" in the Ug calculation, yielding a much longer distance for the shot, and hence a longer exposure time.
: : I hope this helps
: : Juan Amado
: :
: : : Dear friends and colleagues
: : : In double wall radiography of pipes, diameter of wire type IQI sould be based on which of these:
: : : 1- Single wall thickness
: : : 2- Double wall thickness
: : : I have problem for this selection. Logically single wall thickness is the correct selection. But double wall thickness is more practical.
: : : I will be pleased, if you write me your idea and your experience in this case. Please write me which standards suggesting single wall thickness as basis and which of them suggesting double wall thickness as basis for sensitivity calculation and IQI selection.
: : : My email is edalatik@yahoo.com.au
: : : Thank you
: Dear Juan
: thank you very much. Logically, single wall thickness should be used for sensitivity calculation. Sensitivity must be based on single thickness, regardless to exposing technique. But practically, obtaining this sensetivity is impossible in many causes. We need to use X-ray or D4 or MX-125 films or we need to decrease ug.
: If standard suggest s=0.02 based on single wall thickness, ug, sfd, film type source type should be re-defined.
: What is your experince in this cause. Can you obtain s=0.02 based on single wall thickness easily.
: Ragards
: Kaveh
------------ End Original Message ------------




 
15:55 Feb-11-2015
norman tucker
Re: IQI selection in double wall radiography of pipes In Reply to Kaveh Edalati at 01:52 Sep-10-2005 (Opening).

it all depends on the code your working to, but yes most of the time , IQI selection is for double wall expose single wall view is , one wall plus reinforcement .

 
11:16 Dec-28-2015
Andy Wilson
Re: IQI selection in double wall radiography of pipes In Reply to norman tucker at 15:55 Feb-11-2015 .

IQI selection is based on "Single Wall thickness and maximum reinforcement allowed by the referencing code section ASME V".

ASME V Table T-276 Gives you the Required ESSENTIAL Wire for a given penetrated thickness TO BE VISIBLE. for both SS and FS you can see that FS always requires you to see a Thinner wire. at 25 mm you need to see wire 10 SS but for FS its wire 9 so I think this as been taken into consideration as you will normally pull out an additional wire with IQI FS.

 
14:30 Oct-11-2018
Nirav Tailor
Re: IQI selection in double wall radiography of pipes In Reply to Kaveh Edalati at 01:52 Sep-10-2005 (Opening).

Dear sir,

I have doubt. That In 2" pipe, double wall double image technique used and wire type IQI placed on pipe(source side) but that wire type IQI width more than pipe OD. And our required 5th wire is visible on film but it is out side that weld seam . Is it acceptable or not?

 
19:02 Oct-11-2018

N B Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
101
Re: IQI selection in double wall radiography of pipes In Reply to Nirav Tailor at 14:30 Oct-11-2018 .

Why don't you place the wire IQI in such a manner that the required 5th wire is on the weld? Let other wires & ID etc. fall on film.

Regards

 
19:14 Oct-11-2018
Nirav Tailor
Re: IQI selection in double wall radiography of pipes In Reply to N B Rengaraju at 19:02 Oct-11-2018 .

Thank you sir for giving me reply.

Pipe OD is 21.7 mm. And wire type IQI up to 3 wire are fall on weld seam but 4,5,6 wire are out that pipe.
So this type of film to be accepted or given for R/S?

 
21:01 Oct-11-2018

N B Rengaraju

NDT Inspector, NDT Level-III/Radiation Safety Officer(RSO)
Marine and Heavy Engineering Company, MALAYSIA.,
India,
Joined Sep 2014
101
Re: IQI selection in double wall radiography of pipes In Reply to Nirav Tailor at 19:14 Oct-11-2018 .

I hope it's ASTM wire IQI set 1-A. In this condition, if 3rd wire on weld is seen in radiograph then it's acceptable. But if it's not visible & the required 5th wire is not on the weld at all, then it's R/S.

Regards

 


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