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Technical Discussions
Kulsekaran
Kulsekaran
04:25 Mar-12-2007
RT Sensitivity calculation

Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.



    
 
 
Collin Maloney
NDT Inspector, - Plant Inspector
Applus RTD, Australia, Joined Nov 2000, 147

Collin Maloney

NDT Inspector, - Plant Inspector
Applus RTD,
Australia,
Joined Nov 2000
147
03:36 Mar-13-2007
Re: RT Sensitivity calculation
----------- Start Original Message -----------
: Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
------------ End Original Message ------------

Without knowing what sections you are referencing, I think that you will find that the DWDI sensitivity calculation is where both sides of the weld are superimposed.



    
 
 
Nigel
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
03:55 Mar-15-2007
Re: RT Sensitivity calculation
----------- Start Original Message -----------
: Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
------------ End Original Message ------------

Here is a thread which discussed this topic fairly exhaustively. Go through the forum's threaded archives and you will find other threadds dealing with the same topic.

http://www.ndt.net/wshop/forum/messages-1/6128.html




    
 
 
G.Madhesan
Consultant, Welding ýnspector/QAQC inspector
CHENNAI UNIVERSITY, Turkey, Joined Nov 2004, 10

G.Madhesan

Consultant, Welding ýnspector/QAQC inspector
CHENNAI UNIVERSITY,
Turkey,
Joined Nov 2004
10
00:23 Mar-15-2007
Re: RT Sensitivity calculation
For Double wall double image(DWDI) shall be included duouble thickness plus and both side reinforcement for the sensitivity calculations;


----------- Start Original Message -----------
: : Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
: Here is a thread which discussed this topic fairly exhaustively. Go through the forum's threaded archives and you will find other threadds dealing with the same topic.
: http://www.ndt.net/wshop/forum/messages-1/6128.html
------------ End Original Message ------------




    
 
 
Nigel
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
08:36 Mar-16-2007
Re: RT Sensitivity calculation
I believe Mr Madhesan is correct in relation to European Standards but not to ASME. In the standards EN 462 and EN 1435 sensitivity calculations for DWDI are based on double wall thickness. But ASME V Article 2 Paragraph T-276.2(a) Welds with Reinforcements states: "The thickness on which the IQI is based is the nominal single-wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing Code section....The actual measurement of the weld reinforcement is not required."

Thus I think that the INTENT of the ASME Code is that the sensitivity calculation is based on the SINGLE wall thickness.

This makes sense, especially in the case of an elliptical shot, as though the radiographic technique is termed Double Wall Double Image each wall image int he readable portion og the radiograph is to be viewed separately. Therefore an indication of the thickness sensitivity of the radiographic technique to that particular wall thickness will be based on the ratio of the thinnest visible wire to the SINGLE wall thickness. If two wall thicknesses are used for this calculation then the resultant percentage figure will be relevant to an item with a wall thickness double that of the pipe under examination. If a sensitivity figure of 2% is required then it will be much easier to achieve using double wall thickness than single wall thickness.

Where the image is Double Wall Superimposed then there is more logic in taking the double wall thickness for sensitivity calculation.

Perhaps the best way forward is to ensure that your Authorised Inspector or your client's QA agrees with how you intend to calculate radiographic sensitivity.

----------- Start Original Message -----------
: For Double wall double image(DWDI) shall be included duouble thickness plus and both side reinforcement for the sensitivity calculations;
:
: : : Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
: : Here is a thread which discussed this topic fairly exhaustively. Go through the forum's threaded archives and you will find other threadds dealing with the same topic.
: : http://www.ndt.net/wshop/forum/messages-1/6128.html
------------ End Original Message ------------




    
 
 
Kulasekaran
Kulasekaran
03:42 Mar-17-2007
Re: RT Sensitivity calculation
Mr. Nigel and Mr Madhesan,
Thanks for the reply.
Still have doubt about following,
As per BS 2910:1986, clause 13, tells about the same as explained by you. But it seems in Note 1, tells something different?
However, EN 1435:1997, tells For SWSI technique we have to consider nominal wall thickness (i.e single wall thickness). For DWSI & DWDI Penetrated wall thickness i.e.Two wall thickness.
May I misinterpreted the standards? Please clarify.
----------- Start Original Message -----------
: I believe Mr Madhesan is correct in relation to European Standards but not to ASME. In the standards EN 462 and EN 1435 sensitivity calculations for DWDI are based on double wall thickness. But ASME V Article 2 Paragraph T-276.2(a) Welds with Reinforcements states: "The thickness on which the IQI is based is the nominal single-wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing Code section....The actual measurement of the weld reinforcement is not required."
: Thus I think that the INTENT of the ASME Code is that the sensitivity calculation is based on the SINGLE wall thickness.
: This makes sense, especially in the case of an elliptical shot, as though the radiographic technique is termed Double Wall Double Image each wall image int he readable portion og the radiograph is to be viewed separately. Therefore an indication of the thickness sensitivity of the radiographic technique to that particular wall thickness will be based on the ratio of the thinnest visible wire to the SINGLE wall thickness. If two wall thicknesses are used for this calculation then the resultant percentage figure will be relevant to an item with a wall thickness double that of the pipe under examination. If a sensitivity figure of 2% is required then it will be much easier to achieve using double wall thickness than single wall thickness.
: Where the image is Double Wall Superimposed then there is more logic in taking the double wall thickness for sensitivity calculation.
: Perhaps the best way forward is to ensure that your Authorised Inspector or your client's QA agrees with how you intend to calculate radiographic sensitivity.
: ----------- Start Original Message -----------
: : For Double wall double image(DWDI) shall be included duouble thickness plus and both side reinforcement for the sensitivity calculations;
: :
: : : : Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
: : : Here is a thread which discussed this topic fairly exhaustively. Go through the forum's threaded archives and you will find other threadds dealing with the same topic.
: : : http://www.ndt.net/wshop/forum/messages-1/6128.html
------------ End Original Message ------------




    
 
 
Jimbo
Jimbo
05:32 Mar-26-2007
Re: RT Sensitivity calculation
----------- Start Original Message -----------
: Mr. Nigel and Mr Madhesan,
: Thanks for the reply.
: Still have doubt about following,
: As per BS 2910:1986, clause 13, tells about the same as explained by you. But it seems in Note 1, tells something different?
: However, EN 1435:1997, tells For SWSI technique we have to consider nominal wall thickness (i.e single wall thickness). For DWSI & DWDI Penetrated wall thickness i.e.Two wall thickness.
: May I misinterpreted the standards? Please clarify.
: : I believe Mr Madhesan is correct in relation to European Standards but not to ASME. In the standards EN 462 and EN 1435 sensitivity calculations for DWDI are based on double wall thickness. But ASME V Article 2 Paragraph T-276.2(a) Welds with Reinforcements states: "The thickness on which the IQI is based is the nominal single-wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing Code section....The actual measurement of the weld reinforcement is not required."
: : Thus I think that the INTENT of the ASME Code is that the sensitivity calculation is based on the SINGLE wall thickness.
: : This makes sense, especially in the case of an elliptical shot, as though the radiographic technique is termed Double Wall Double Image each wall image int he readable portion og the radiograph is to be viewed separately. Therefore an indication of the thickness sensitivity of the radiographic technique to that particular wall thickness will be based on the ratio of the thinnest visible wire to the SINGLE wall thickness. If two wall thicknesses are used for this calculation then the resultant percentage figure will be relevant to an item with a wall thickness double that of the pipe under examination. If a sensitivity figure of 2% is required then it will be much easier to achieve using double wall thickness than single wall thickness.
: : Where the image is Double Wall Superimposed then there is more logic in taking the double wall thickness for sensitivity calculation.
: : Perhaps the best way forward is to ensure that your Authorised Inspector or your client's QA agrees with how you intend to calculate radiographic sensitivity.
: : ----------- Start Original Message -----------
: : : For Double wall double image(DWDI) shall be included duouble thickness plus and both side reinforcement for the sensitivity calculations;
: : :
: : : : : Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
: : : : Here is a thread which discussed this topic fairly exhaustively. Go through the forum's threaded archives and you will find other threadds dealing with the same topic.
: : : : http://www.ndt.net/wshop/forum/messages-1/6128.html
------------ End Original Message ------------

The IQI selection should be based on the thickness of the area of interest.



    
 
 
Tauqir Ahmad Gondal
Tauqir Ahmad Gondal
01:39 Oct-28-2007
Re: RT Sensitivity calculation
I believe both Standards (EN and ASME)are correct. European Standards are defining in details for all techniques and in other hand ASME is talking as general.
If RT technique is DWSI, Sensitivity shuold be calculated for single wall plus cap height (theoratical)i.e please see ASME B 31.3 table 341.3.2, in SWSI or DWSI our intrested area is single wall only.
In DWDI (Elliptical or Superimposed)technique sensitivity should calculate single wall plus cap height multyply by 2, because both walls are readable.
----------- Start Original Message -----------
: I believe Mr Madhesan is correct in relation to European Standards but not to ASME. In the standards EN 462 and EN 1435 sensitivity calculations for DWDI are based on double wall thickness. But ASME V Article 2 Paragraph T-276.2(a) Welds with Reinforcements states: "The thickness on which the IQI is based is the nominal single-wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing Code section....The actual measurement of the weld reinforcement is not required."
: Thus I think that the INTENT of the ASME Code is that the sensitivity calculation is based on the SINGLE wall thickness.
: This makes sense, especially in the case of an elliptical shot, as though the radiographic technique is termed Double Wall Double Image each wall image int he readable portion og the radiograph is to be viewed separately. Therefore an indication of the thickness sensitivity of the radiographic technique to that particular wall thickness will be based on the ratio of the thinnest visible wire to the SINGLE wall thickness. If two wall thicknesses are used for this calculation then the resultant percentage figure will be relevant to an item with a wall thickness double that of the pipe under examination. If a sensitivity figure of 2% is required then it will be much easier to achieve using double wall thickness than single wall thickness.
: Where the image is Double Wall Superimposed then there is more logic in taking the double wall thickness for sensitivity calculation.
: Perhaps the best way forward is to ensure that your Authorised Inspector or your client's QA agrees with how you intend to calculate radiographic sensitivity.
: ----------- Start Original Message -----------
: : For Double wall double image(DWDI) shall be included duouble thickness plus and both side reinforcement for the sensitivity calculations;
: :
: : : : Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
: : : Here is a thread which discussed this topic fairly exhaustively. Go through the forum's threaded archives and you will find other threadds dealing with the same topic.
: : : http://www.ndt.net/wshop/forum/messages-1/6128.html
------------ End Original Message ------------




    
 
 
Tauqir Ahmad Gondal
Tauqir Ahmad Gondal
00:48 Oct-30-2007
Re: RT Sensitivity calculation

I believe both Standards (EN and ASME)are correct. European Standards are defining in details for all techniques and in other hand ASME is talking as general.
If RT technique is DWSI, Sensitivity shuold be calculated for single wall plus cap height (theoratical)i.e please see ASME B 31.3 table 341.3.2, in SWSI or DWSI our intrested area is single wall only.
In DWDI (Elliptical or Superimposed)technique sensitivity should calculate single wall plus cap height multyply by 2, because both walls are readable.

----------- Start Original Message -----------
: I believe Mr Madhesan is correct in relation to European Standards but not to ASME. In the standards EN 462 and EN 1435 sensitivity calculations for DWDI are based on double wall thickness. But ASME V Article 2 Paragraph T-276.2(a) Welds with Reinforcements states: "The thickness on which the IQI is based is the nominal single-wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing Code section....The actual measurement of the weld reinforcement is not required."
: Thus I think that the INTENT of the ASME Code is that the sensitivity calculation is based on the SINGLE wall thickness.
: This makes sense, especially in the case of an elliptical shot, as though the radiographic technique is termed Double Wall Double Image each wall image int he readable portion og the radiograph is to be viewed separately. Therefore an indication of the thickness sensitivity of the radiographic technique to that particular wall thickness will be based on the ratio of the thinnest visible wire to the SINGLE wall thickness. If two wall thicknesses are used for this calculation then the resultant percentage figure will be relevant to an item with a wall thickness double that of the pipe under examination. If a sensitivity figure of 2% is required then it will be much easier to achieve using double wall thickness than single wall thickness.
: Where the image is Double Wall Superimposed then there is more logic in taking the double wall thickness for sensitivity calculation.
: Perhaps the best way forward is to ensure that your Authorised Inspector or your client's QA agrees with how you intend to calculate radiographic sensitivity.
: ----------- Start Original Message -----------
: : For Double wall double image(DWDI) shall be included duouble thickness plus and both side reinforcement for the sensitivity calculations;
: :
: : : : Can anybody clarify the Wall thickness to be considered for sensitivity calulation when following technique used: Double Wall Exposure, Double Wall Viewing (DWDI) and Double Wall Exposure Single Wall Viewing(DWSI). I noticed different statements for calulation of sensitivity in ASME and BS.
: : : Here is a thread which discussed this topic fairly exhaustively. Go through the forum's threaded archives and you will find other threadds dealing with the same topic.
: : : http://www.ndt.net/wshop/forum/messages-1/6128.html
------------ End Original Message ------------




    
 
 

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