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1700 views
14:39 Oct-01-2009

ihsan Duzgun

NDT Inspector, NDE Supervisor
Cimtas Piping Industries Ltd. Co.,
Turkey,
Joined Sep 2009
4
B31.1 / B31.3 Piping UT with TOFD method

Hello,
One of our customer wants TOFD method for their B31.1 piping Heavy wall pipes. They also wants in use of TOFD technique in lieu of Conventional or PA UT methods.
can we use TOFD method in power or process piping according to code cases 179-181 ?
or is there any restriction to use TOFD under the B31.1 or 31.3 piping codes ?


    
 
16:30 Oct-01-2009

Luis Ganhao

Engineering,
USA,
Joined Sep 2008
25
Re: B31.1 / B31.3 Piping UT with TOFD method In Reply to ihsan Duzgun at 14:39 Oct-01-2009 (Opening).

the code case 181 permit the use of AUT (TOFD & PA) in lieu of RT, but you have to select the most appropriated setting for the examination, I mean you need to check the thickness and after that select de frequency, probe sizes and angles. Regards to the calibration block ASME Sec V Appendix III and BSI-7706 or ENV-583-6 given to you the chance to perform the calibration for TOFD on the pipe material to be inspected. But you need a calibration block for shear wave (this technique is necessary to check the dead zones of TOFD). I have carried out many inspections on pipelines with TOFD in lieu of RT, whose thicknesses were in the order of 9-70 mm, inclusive I could detect cracks generated by service (gas).

I hope this can help you


    
 
16:41 Oct-01-2009

luis ganhao

Engineering,
USA,
Joined Sep 2008
25
Re: B31.1 / B31.3 Piping UT with TOFD method In Reply to ihsan Duzgun at 14:39 Oct-01-2009 (Opening).

Sorry, but the appendix III from ASME SEC V does not apply fro piping (calibration block) so you need is the specifications for your block found in the code case 181, however the BSI-7706 give you the option for calibration over the pipe that you want inspect, I mean this std. offer 4 or 5 different forms to obtain the minimal sensitivity besides you can use the BSI-14751 or ENV-583-6


    
 
16:57 Oct-01-2009

ihsan Duzgun

NDT Inspector, NDE Supervisor
Cimtas Piping Industries Ltd. Co.,
Turkey,
Joined Sep 2009
4
Re: B31.1 / B31.3 Piping UT with TOFD method In Reply to Luis Ganhao at 16:30 Oct-01-2009 .

under the light of code case allows TOFD for B31.3 applications but what about B31.1 power piping ? In code case 179 sect (d) it says about indication evaluation "20% of the reference level shall be investigated to extent UT exam" means DAC and i understand that only amplitude based UT methods shall be permitted and also B31.1 piping refers to ASME sect V article 4 if we check the equipment requirements under T-430/T-431 again we can see "a pulse echo type instrument shall be used" criteria. As far i know TOFD method (im not familar to TOFD applications) is not a pulse-echo or amplitude based UT technique ?
in my opinion, it isnt clear that using TOFD technique in lieu of conventional or PH UT methods for B31.1 Power piping ?


    
 


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