UT testing in lieu of RT in High Temp Power Piping

[muld0020]

Hi all,

I have a customer looking for confirmation that they can substitute phased array UT testing for RT in high pressure/temp P91 and P22 steam piping. I believe the boiler manufacturer only wants to accept RT and our customer wants to use UT. I looked in power piping and it looks like you can substitute UT for RT without any issue in Table 136.4. My experience is mostly in Sec VIII D1/D2 so I know the rules there. I'm not as familiar with power piping and section I.

Thanks for you help.

 

[weldstan]

PA UT can be used in lieu of RT under ASME I and B31.1. Be aware that all NDE service providers who perform PA UT are not alike and the results from the UT may not be as wonderful as your Customer believes.

 

[davefitz]

ToF and phased array UT can provide good results in thick walled piping if the technicians are certified , higher grade techs. A lot of cracks that are not found in RT can be found in a correct UT scan. And, you do not need to evacuate the site as RT requires. UT can help a lot in cases of short outages that cannot afford to evacuate the area for an RT.

"Whom the gods would destroy, they first make mad "

 

[Duwe6]

If you are going to pay for Phased Array, make sure that the provider is using a unit that records the entire scan, encoded for position. After a little 'magic' inside the unit, you will be presented with a 'rollout' of your weld, and it will look like a full-color x-ray [C-scan]. The view can also be shifted so that it is looking sideways through the weld ["D-scan"].

Problem with getting that quality of results is that an unencoded, nonrecording PA unit costs about $20K. The one that can make the 'rollout' views by recording and using encoded position of the scanning head costs about $90K.