Penetrant Inspection

Date 06-25-2010 00:45

For smooth machined parts, searching for faint indications, flourescent would be my choice. Out side in the bright sun would make flourescent difficult to interpret. Rough surfaces such as casting though make regular penetrant a better choice.

By dmilesdot (**)

Date 06-25-2010 11:09

the determination of what penetrant process to use is best left up to an ASNT Level III in that method. There are several different methods and each has its problems/benefits for a given situation. The level III writes the proceedure to give the best results for a given situation, and the Level II performs the test according to the proceedure. But to really answer your question, a ASNT Level III takes all the information about the circumstances of the exam and determines the best method.

By Milton Gravitt (***)

Date 06-25-2010 12:23

Thanks for the help.

By CWI555

Date 06-28-2010 12:57

I would have to differ a little with the previous comments. The first stop should be engineering. While the LIII should be capable of assisting in setting the criteria, or setting where no other information is available, the EOR should be defining what the nature and extent of an indication is acceptable or unacceptable.
Once that information is passed to the NDE LIII, the correct method and sensitivity level can be applied by that LIII.

Regards,
Gerald

By bozaktwo1 (***)

Date 06-28-2010 16:57

I deal with subs which use that fluorescent method on all my welding. It drives me up the wall because it often marks out "defects" which can't otherwise be seen, and are not rejectable under the acceptance criteria. Headaches.

By Milton Gravitt (***)

Date 06-29-2010 16:46

bozaktwo1, we have learned to grind every start and stop and that helps alot.

M.G.

By bozaktwo1 (***)

Date 06-29-2010 16:52

:) If starts and stops were the only problem, I would have no problems at all!

By jrw159

Date 06-29-2010 16:58

Curt,
I would have more of an issue with subs that are marking up defects that are not rejectable per the criteria than I would with their method of finding them. It reflects poorly on them, not the NDE process.

jrw159

By bozaktwo1 (***)

Date 06-29-2010 21:30

Agreed. But what do you do when using a customer qualified NDI house and the parts are rejected? You take them to yet another customer qualified NDI house where they are accepted, and without having done any rework to the parts. So I am removing all my aluminum parts from that vendor. I have the feeling that this particular vendor doesn't want my business, which doesn't hurt them - they have contracts out the yingyang with OEMs and don't need our piddly jobs...however we need them for their qualifications with our customer! It's a vicious circle, man. Hopefully that qualified vendor list will pick up a few additions this year.

By jrw159

Date 06-29-2010 23:50

I completely understand your issues, been down that road. I was just pointing out that it does not sound like the NDE process is (or in this case was) the problem. :-)

jrw159

By bozaktwo1 (***)

Date 06-30-2010 16:35

Gotcha. I agree, but still think if they're going to use a high-sensitivity method, they need to have a more experienced interpretation.

By jrw159

Date 06-30-2010 16:50

"they need to have a more experienced interpretation."

Exactly. :-)

jrw159

By eekpod

Date 06-30-2010 19:56

Ive seen situations where solvent removable was used where water washable should have been used, and they could never got all the PT out of the alum casting, what a mess.
So be careful its not just what color, its also which method.
Chris

By Milton Gravitt (***)

Date 06-30-2010 22:28 Edited 07-01-2010 12:03

So for we've sent 15 aluminum boxes to be tested and 4 of the 15 had cracks or flaws, but can be repairable.

M.G.

By Superflux (****)

Date 06-30-2010 22:37

eekpod,
Know what ya mean.
I hate it when that happens! It's like puttin the bicycle together on Christmas Eve before reading the instructions, and after the egg nog.
Even the simplist of tasks can have hidden secrets..........
Depending on the chemistry, once water is introduced to a solvent based compound (or vise-a-versa), it sometimes turns into a "plasticized" goop that then resists any known method of clean-up.

Don't ask me how I know this...it happened to a "friend of mine"....ahem, cough, cough. At least now I know why there is a Level III PT cert

By eekpod

Date 07-01-2010 10:10

Superflux, yup I know that guy also, and yes it does make a mess. :)

By mroach

Date 07-09-2010 08:34

That is the very reason why the NDT Level III establishes the test procedure. Where the engineer may decide what type of indication may be most detrimental to the service life of the part most engineers are not aware of the mechanics of the test itself. Based on what the engineers specification as to what is considered detrimental is only the start for the NDT Level III to determine which method may be more suitable. The chemical composition of the penetrant testing method itself with regards to sulfide or cloride content may have an adverse affect on the material being tested. The normal surface appearance is usually a determining factor for visual criteria. Temperature and othe environmental factors will determine the reactance of the method applied. In this instance the part is aluminum that will be repaired therefore post cleaning may be considered a critical part of the procedure in that there is no cross contamination with the filler material. These are just some of the considerations that must be made before a particular dye penetrant test method is applied.