Computed Radiography (CR)

Date 11-12-2009 13:21

They already do. For example, for D1.1 refer to Part G of Clause 6. There it basically says you can use any RT technique, as long as it is approved by the Engineer, and then it goes on to describe what the RT procedure must contain.
Mankenberg

By pax23

Date 12-08-2009 12:24

I guess the real question is whether or not D1 will incorporate CR into its standard code blessed RT procedure in Section 6, Part E. As I read it, 6.17.4 mandates physical film and thereby excludes CR. Yes, you can still use Part G but it can be a hassle getting approval.

By Metarinka (****)

Date 12-09-2009 20:26

probably a chicken and egg thing. Fabricators won't invest in equipment that can't do code work (VBR, CR) hence there's little pressure to have it included in codes. And since there's no sight of it being included, fabricators won't invest in the technology.

To my basic understand of CR, the part needs to be rotated? is that correct? my guess is between the high capital costs and limited applicability to most welding tasks, it will be sometime before we see code acceptance of the practice.

By HgTX

Date 12-09-2009 21:19

As far as I know, there's nothing inherent about CR that requires rotating the part, though maybe there are some setups out there that do. What I've seen is a reusable screen that fits into the same cassette as the film does, and then the screen goes into a reader instead of into a developer. I forget after how many shots it's supposed to pay for itself (and I forget whether that number would be measured in hundreds or thousands).

Hg

By Metarinka (****)

Date 12-09-2009 21:55

oh excuse me, I'm thinking of computed tomography and real-time xray machines. I can't find a link right now.

The part is spun on a positioner while xrays are taken at every angle. It produces a 3d file that gives you accurate results related to the volume, size and density of inclusions. The downside to some of the systems is that it has to be spun while the source shoots the parts from every angle. Some linked a a research page of university in which they were shooting video of moving motors and a full VW bug with such a system.

So we are talking about the sources that are digitally scanned, and then reusable? I wasn't aware they weren't accepted code wise. My good friend is an x-ray technician in a hospital and traditional film sources are all but abandoned, as the newer sources are much more consistent, faster and cheaper.

By HgTX

Date 12-09-2009 22:19

Digitally scanned & reusable, many times. So you save on consumable costs, plus it takes significantly less exposure to achieve the same results. So you could spend less time and/or use a weaker source.

There are a few things in the code that would need to be tweaked for it to be acceptable, I think.

Hg

By Metarinka (****)

Date 12-09-2009 22:24

yah I'm thinking of http://www.xtekxray.com/products/computed_tomography.html I don't think CT systems have recieved any code acceptance yet for welding applications. Seems like overkill for most welding anyways, although it may catch defects that a normal 2d xray shot in a static plane would miss.

the digitally scanned systems are nice does away with the densitometers and all that. But it becomes pricey as you have to use a monitor that's been calibrated and all that. Also are the plates bendable like a traditional film source for wrapping around pipe? The one I saw when I busted up my wrist used plates in side of a rigid plastic container. That was put into a scanner that did it's thing. Didn't think it was flexible though?

By HgTX

Date 12-09-2009 23:01

The ones I saw looked flexible.
http://www.carestreamhealth.com/ndt-flexPlates_sellSheet.pdf

Hg