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Thread: IQI Penetrameters/Sensitivity

  1. #1

    IQI Penetrameters/Sensitivity

    Hi brothers

    Not sure where to stick this post but I am having trouble locating in either asme or eu standards the reason for IQI sensitivity to be measured at 2% or better.

    Could someone point me in the right direction please and maybe pinpoint the relevent info in ASME V? I am not an NDT tech nor am I knowledgable in that area.

    This is rather urgent -

    Many thanks

    Verdi


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  5. #3

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    Re: IQI Penetrameters/Sensitivity

    Hello Verdi!
    I believe you will not find this in either ASME or EN because, normally, this is a Customer or Spec requirement.
    Do you know how to calculate the equivalent wire diameter/thickness to radiograph?
    Consider:

    IQI Sensitivity

    The smallest element readily visible in the area under inspection is used to determine IQI sensitivity

    For the wire type IQI: %Sensitivity = Diameter of the smallest vissible wire / Thickness of metal * 100

    For the step-hole IQI:

    %Sensitivity = Diameter of the smallest vissible hole / Thickness of metal * 100

    For the plaque hole IQI there are two different approaches as follows:

    The first approach is to use the Australian Standard formula for sensitivity defined in AS2177:

    %Sensitivity = sqrt(AxB/2)

    Where:

    A is the thickness of the smallest plaque image visible, expressed as a percentage of metal thickness
    B is the diameter of the smallest hole visible, expressed as a percentage of metal thickness
    The second approach is to use the American (ASME) system for IQIs. American standards set a required IQI sensitivity in terms of the plaque thickness and the smallest hole visible in the radiograph. A code may require a 2-2T sensitivity or a 1-2T sensitivity. No reference is made to percentage sensitivity.

    The first number refers to the size of the plaque to be used, a plaque whose thickness is 2% in the first case, or 1% in the second case, of the thickness of the metal being radiographed. The second number (2T) states that the 2T (twice the thickness) hole shall be visible in the radiographic image. Hence it is a go/no-go test, with no determination of actual percentage sensitivity. This is a far more sensible use of the plaque hole IQI. The Australian approach requires affixing several plaques to the test object to find the thinnest visible plaque and the smallest visible hole to arrive at a meaningless number.

    There are two important factors relating to IQI sensitivity

    The sensitivity determined is a function of the type of IQI used. A 2% sensitivity with a wire type IQI is not the same as a 2% sensitivity with a step hole or plaque hole IQI.
    The IQI sensitivity is not a measure of the smallest detectable discontinuity in the test object. IQI sensitivity is a measure of the quality of the image, and is a means of controlling and assessing image quality.

    For more information go to:

    [link Point to another website Only the registered members can access]


  6. #4

    Join Date
    Mar 2011
    Location
    Portugal
    Posts
    637

    Re: IQI Penetrameters/Sensitivity

    Hello Verdi!
    I believe you will not find this in either ASME or EN because, normally, this is a Customer or Spec requirement.
    Do you know how to calculate the equivalent wire diameter/thickness to radiograph?
    Consider:

    IQI Sensitivity

    The smallest element readily visible in the area under inspection is used to determine IQI sensitivity

    For the wire type IQI: %Sensitivity = Diameter of the smallest vissible wire / Thickness of metal * 100

    For the step-hole IQI:

    %Sensitivity = Diameter of the smallest vissible hole / Thickness of metal * 100

    For the plaque hole IQI there are two different approaches as follows:

    The first approach is to use the Australian Standard formula for sensitivity defined in AS2177:

    %Sensitivity = sqrt(AxB/2)

    Where:

    A is the thickness of the smallest plaque image visible, expressed as a percentage of metal thickness
    B is the diameter of the smallest hole visible, expressed as a percentage of metal thickness
    The second approach is to use the American (ASME) system for IQIs. American standards set a required IQI sensitivity in terms of the plaque thickness and the smallest hole visible in the radiograph. A code may require a 2-2T sensitivity or a 1-2T sensitivity. No reference is made to percentage sensitivity.

    The first number refers to the size of the plaque to be used, a plaque whose thickness is 2% in the first case, or 1% in the second case, of the thickness of the metal being radiographed. The second number (2T) states that the 2T (twice the thickness) hole shall be visible in the radiographic image. Hence it is a go/no-go test, with no determination of actual percentage sensitivity. This is a far more sensible use of the plaque hole IQI. The Australian approach requires affixing several plaques to the test object to find the thinnest visible plaque and the smallest visible hole to arrive at a meaningless number.

    There are two important factors relating to IQI sensitivity

    The sensitivity determined is a function of the type of IQI used. A 2% sensitivity with a wire type IQI is not the same as a 2% sensitivity with a step hole or plaque hole IQI.
    The IQI sensitivity is not a measure of the smallest detectable discontinuity in the test object. IQI sensitivity is a measure of the quality of the image, and is a means of controlling and assessing image quality.

    For more information go to:

    [link Point to another website Only the registered members can access]


  7. #5

    Re: IQI Penetrameters/Sensitivity

    the 2% comes from ASTM E94 6.2
    but everyone goes by Table T-276 in ASME sec V
    or Appendix B in EN ISO 17636-1
    wich is basically what the above post says without having to do the calculations

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