ASME cluster porosity

Date 02-10-2009 21:08

My RT guy was telling me a story about and argument between him and the AI regarding cluster porosity. Basically, the level II as well as another level II both rejected the same weld for cluster porosity, but the AI claimed it to be random indications. The level II was reffered to APPENDIX 4 of sec VIII, but couldn't find a clear definition for cluster porosity.

This got me to look it up for myself, and frankly, I myself am confused. Simply by looking at figure 4-3 and 4-4, what would make the examples to the far right of 4-3(a) and the far right of 4-4(b) not cluster porosity?

For example, fig 4-6 (c) shows a cluster. Figure 4-6 (b) shows what seems to be a cluster on the left. Obviously there are fewer indications, but would that not be considered a cluster too. Or "randomly dispersed" (see 4-3(f)).

By CWI555

Date 02-10-2009 21:55

Appendix 4 quotes:
para (f) Rounded Indication Charts. The rounded indications
characterized as imperfections shall not exceed that shown
in the charts. The charts in Figs. 4-3 through 4-8 illustrate
various types of assorted, randomly dispersed and clustered
rounded indications for different weld thicknesses greater
than 1/8 in. (3 mm). These charts represent the maximum
acceptable concentration limits for rounded indications.

para (h) Clustered Indications. The illustrations for clustered
indications show up to four times as many indications in
a local area, as that shown in the illustrations for random
indications.

Be sure to read the verses in light of the following:
All charts show max values.
Clustered will always have a higher concentration than the max shown for randoms.

If you look at 4.4 A. That is the maximum value. Anything that exceeds that value in concentration, is considered clustered. The same goes for 4.3 etc.

Regards,
Gerald

By new tito (***)

Date 02-10-2009 22:39

Thanks for the explanation, Gerald. I think I understand a little better now.

I guess if looking at a radiograph, you have to consult the figures to determine if it is considered random or cluster? As in, there is no clear cut definition?

By CWI555

Date 02-11-2009 03:14

Yes you have to consult the radiographs. Keep in mind the images as found in section 8 cannot be reduced or enlarged and are intended to be printed on standard 8.5 x 11" paper. So what happens when you use A4 which is 8.27x11.69" ? Most printers fill to fit the paper which ends up enlarging these images. My personal opinion of this is that it's a severally outdated mode. Even the printing of the hard copies from ASME is subject to minor variations. It's highly subjective, but then again, that is where experience comes in.