margin thicknesses that can radiography as per ASME

[yassinoboss]

I am a compliance officer in NDT a metal construction company, now we are working on a thermal power plant project, our client requests the control RT From a thickness of 72 mm, and as you know it's impossible to do, he asks me a justification ASMEV, when I made ​​an effort on ASME but I found nothing as a justification to convince him to change RT by UT.

I would like you to answer me if you know response on the margin of thickness that can radiography as per ASME.

thank you

 

[aburafdi]

Hello yassinoboss,
In ASME BPV Sect I, table PW-11 note (a) saying that : "........UT of the weld shall be performed in lieu of RT when it is impracticable to use combination of radiographic parameters such that a geometric unsharpness of 0.07 in (1.8 mm) will not be exceeded...."
For the formula of geometric unsharpness itself, you can find in PW-11.3

 

[JR97]

Yassinoboss,

72 mm thickness is not impossible to RT. It may be impossible with the x-ray tube or isotope that your company has; but it is not impossible. I suggest if your client resists UT that you search in your area for a company with a high energy machine or Cobalt isotope to allow the RT to be completed in accordance with ASME V.

JR97

 

[Duwe6]

High-energy X-ray is a 'shop' process. Cobalt-60 will just barely do 72mm / 2¾". Ask the customer if drilling in RT holes "Gamma Ports" to enable the RT firm to be able to place a J-tube in the center of the completed pipe will be acceptable. If/when he says 'no', then the only Code alternatives are UT - prefferably Phased Array; or TOFD, using UT or UT-Phased Array to 'prove up' the indications that TOFD finds.

You need a discussion with a GOOD NDT provider. Just ask if they have 'Cobalt', 'Phased Array', and 'TOFD'. If they have access to all three, those are the people to talk to about capabilities and what will meet Code requirements. 72mm is a very thick wall, and the 'Mom & Pop' x-ray firms cannot do you a really good job.
Get the 'Big Guys', and pay their prices.

 

[stanweld]

Ir 192 is routinely used to radiograph 72 mm wall thickness pipe using a gamma plug for a panoramic shot. If the Ug cannot be obtained, UT examine per Code Case 2235-9. Co 60 can be used for a double wall shot but the image produced is poor.

If I were the owner, I would have no problem using UT if RT cannot produce reasonable results.

 

[yassinoboss]

thank you all for your efforts.
I'm sorry, I'm not well expressed my request.

but your answer really helped my M aburafdi.
I thank you also JR97,Duwe6 , stanweld