Forged UT examinations

Date 11-15-2012 17:31

I was wondering if anyone has experience with doing any UT Examinations on Forged parts with ASTM standards. I just started this new position and I am heading up their new NDE department. I am experiecened in AWS and some ASME on welded connections but now I am jumping in head first with these Forged Rings. I/we will be doing PT, UT and eventually MT on these. We have a current complany doing all of our NDE and hopefully in a month I can take over that and start getting a couple trainees on board to start getting their hours. I have a Responsible Level III who has jsut started going over our procedures I have rough drafts for. After reading all of the the different specs and looking over all of the different standards I have noticed their a few things that as a UT tech I have never came accross. One example is a ID/OD ratio, not sure exaclty what this is but I am sure it is a calculation and it relates to thicknesses and the ID and OD. Depending on the ratio determines type and location of exam i.e. Shear or Longitudinal waves.

My company knows I don't have experience with this type of work, I just wanted to get a good feel for it and see if anyone has any comments. I do see a few areas for concern that the current contracted NDE firm that is doing our examinations.

By CWI555

Date 11-15-2012 23:07

That wouldn't happen to be wind tower flanges would it? And yes, they are a PIA.

By CWI555

Date 11-15-2012 23:28

As a rule of thumb, exclusive of any given standard, the base problem with ID OD ratio's is when it hits (or not) the ID surface. If it impinges upon the ID surface > critical angle you will get a bounce. If it impinges on the ID surface = critical angle, it will graze the ID surface, setting up surface waves, and other mode conversions on that surface, as well as passing part of the initiating beam on through the main body of the piece. If you hit it at < critical angle, it will shoot on through the body with only a bit of the beam spread catching the ID if anything.

Forgings are a PIA in that the grain structure is not isotropic but rather anisotropic. Your beam has a nasty habit of not traveling the imaginary straight line a lot of UT hands believe it to be. The near surface tends to be isotropic (the same in all directions), but further into the body of the forging, it tends to turn anisotropic (directionally dependent).
That would have more to do with utilization of Refracted L waves rather than the ID OD ratio. (that is only one of many concerns)

I am not normally negative, but you've bitten into something that's going to bite back if your not careful.

By supermoto (***)

Date 11-16-2012 13:54

I don't think we do any wind tower flanges as our rings are at a maximum of 100"in dia.

I can see what your saying about this and I have two questions:

1.) How do I figure the ID/OD ratio to see if shear wave is applicable so I know what ring gets this method of examination.

2.) I guess I am not too worried about a second leg exam as most indications with shear wave I would most likely see in the first leg scanning on a machined surface. With the exception of near surface indications. Correct me if I am wrong as I am still a newbie in a lot of areas even as a level II with only 4 years of experience.

The next hurdle will be making sure I have the correct calibration standards and also making sure the Radius isn't too tight where I would need a special type of contoured wedge, but maybe that has something to do with the ID/OD ratio being 2:1.

By CWI555

Date 11-16-2012 16:17

Impinging angle
Angle at ID = Sin1 * (OD/ID)
Shear wave angle from L wave probe
shear angle = Sin1 * (V2/V1)

By supermoto (***)

Date 11-16-2012 17:07

Your terminology is a little different then I am used to. I interpret what your saying like so:

Using Contact methods = Sin1 45deg x (36"/30") = .84(is the OD/ID ratio?) which is less than 1.5 OD/ID ratio

Not sure what you mean in the information below other than L-Wave is SB and since I am using contact methods do you mean V1= wedge material(lucite) and V2= Material tested?
Shear wave angle from L wave probe
shear angle = Sin1 * (V2/V1)

This is what the spec says:
Shafts and Cylinders scanned from the periphery (OD) and, when reportable indications are found, from both faces. A shear wave test shall be performed on hollow or bored parts whose ratio of OD/ID is 1/5 or less.

This is pulled from the spec also:

Shear wave Examination (See 5.2.2)
7.4.2.1 For rings with OD/ID ratios of 1.5 to 1.35 a 40° search unit shall be utilized.
7.4.2.2 For rings with OD/ID ratios of 1.35 or less a 45° search unit shall be utilized.

Angle Beam Examinations
6.3.2.1 Use a 1 MHz, 45° angle beam search unit unless thickness, OD/ID ratio, or other geometric configuration results in failure to achieve calibration. Other frequencies may be used if desirable for better resolution, penetrability, or detectablility of flaws. For angle beam inspection of hollow forgings up to 2 to 1 OD/ID ratio, provide the transducer with a wedge or shoe that will result in the beam mode and angle required by the size and shape of the cross section under examination.

This stuff can get pretty complicated by written communitcation, but I appreciate any and all efforts to help a newbie.

By crgodfrey Date 12-19-2012 18:24

Hey Noah!

By supermoto (***)

Date 12-19-2012 21:56

Who are you Crgodfrey, do I know you?

By crgodfrey Date 12-20-2012 12:10

"Phased Array"