Fluorescent Penetrant Inspection Assistance Needed

[cjohnso0]

Greetings everyone,

I am looking for help with an FPI-related discussion I am having with our local Level III. I have the requirement to FPI a certain part using a 1D2 class penetrant (Medium Sensitivity, Post Emulsified). Unfortunately, we are unable to process this component with this penetrant. I would like to change the requirement to 1A2 or 1A3 class penetrant, which is water washable, Medium or High.

According to my Level III, this is not possible because all P/E penetrants are of a higher sensitivity than the W/W. I.E. he feels that the 1D2 penetrant is higher sensitivity than a 1A3 or 1A4. I am not convinced, as he has no data to back this up.

Is anyone familiar with penetrant classification, and their sensitivities. Any data backing up either argument is good. For the record, the OEM will allow our local Level III to change this requirement, but I need to convince him it is a sound change.

Thanks in advance,

Chris

 

[rb1957]

this is an a/c inspection ? how can you change the inspection technique (on your own authority) ??

i'd discuss it with the OEM's customer support people.

 

[WKTaylor]

cjohnson0 ... You are a bit thin on specification details...

What penetrant inspection specification are You using: ASTM E1417? Military T.O./TM/NAVAIR? SRM? MIL-STD-1907? AMS2647?

What defect accept/reject CRITERIA [SPEC] are You using: Military T.O./TM/NAVAIR? SRM? MIL-STD-1907? SAE AS3071? AMS2647?

What sensitivity level do You require: 1/2 and 1 (very coarse), 2 (attainable in-the-field), 3 (typical, back-shop) or 4 (max sensitivity, back-shop)???

NOTE. Sensitivity requirement is based on need to ID smaller-and-smaller local defects.

Sensitivity level 1/2 is for very coarse defects... probably easily visible to the trained, naked-eye; but sensitivity level 4 is for finding very fine [fly-shit in-the-pepper] defects. I have specified level 4 only a few times... where even tiny defects are unacceptable.

May we assume You are using penetrant inspection materials per AMS2644E? Table 2 lists materials based on sensitivity and removability: have You looked "there"?


Regards, Wil Taylor

 

[cjohnso0]

Thanks for the replies,

We are an engine repair facility, working to an OEM standard practice specification. This spec is based on SAE-AMS-2644 and references the penetrant / classifications listed in the AMS spec.

The issue is that the OEM repair manual is requesting us to FPI certain areas of the part, some with the 1A2 penetrant (as specified by AMS 2644) and some with the 1D2 penetrant. The sensitivity required is 2, but the OEM is listing both water washable and post emulsifiable, depending on which areas of the part we repair. I am looking for a way to use only water washable, as we cannot locally apply the post-emulsified.

My basic question is a sensitivity 2 water wash penetrant equivalent to a sensitivity 2 post emulsified penetrant. From looking at AMS 2644, it appears so, but our Level III NDT inspector is claiming that no class of the water washable penetrants are even as good as a sensitivity 2 post emulsified. He claims that a 1A4 penetrant is not as sensitive as a 1D2 penetrant. This makes no sense to me, but I'm not an NDT expert by any means.

In the OEM specification for NDT, they clearly allow us to change the classification of the penetrant used, if the local Level III inspector approves of it.

Thanks again

 

[Sparweb]

I'm curious as to why you cannot apply the post-emulsified dye. I didn't see a reason given.

Steven Fahey, CET

 

[cjohnso0]

SparWeb,

Apparently we cannot apply the emulsifier, the penetrant is not an issue. According to the tech data from the OEM, we need to immerse or apply via foam spray the emulsifier. Do to the part configuration we cannot immerse it, as it is too large for our facilities.

Another reason being I would like to not have to process certain areas by post emulsified, and others by water wash, provided they will yield equivalent results. This is what the OEM specifies.

 

[WKTaylor]

cjohnson0...

You have not mentioned the base alloy type(s) You are inspecting... and whether they are turbine or piston parts. Everything comes into play with parts that start dirty and have seen significant heat/stress.

Also...

Is/are there some materials sensitivity or follow-on repair-ability issue here? IE; is/are the base alloy(s) is susceptible to corrosion, SCC... or is it (are they) too hard to clean so that grind/weld repair is compromised? If there multiple parts forced together (press-in bushings, pins, etc), then extreme care is required with materials selection.

Odd. For turbine, and even piston engine, non-ferrous parts sensitivity level 2 is just a little better than a good visual inspection. These must be secondary components with high durability.

Sensitivity level for the penetrant material is USUALLY set based on the molecular size of the FP material... and their ability to migrate into cracks by capillary action. As-long as the base metal is not excessively dirty [hard to clean] is "smeared" or is heavily corroded, then the higher the sensitivity, then the finer the defects it can "penetrate" into. NOTE. due to FPI complexity, many shops just standardize on one process or the other... and is usually Level 3 is a good compromise... although might show more defects than needed... keeps NDI techs/engrs busy sorting out what is in/out of limits. Surface cleaning processes come into play: some residues are "phobic" [repulsive] and some are "philic" [attractive] to the FPI agents. Ahhh... so complex.

USAF T.O. 33B-1-1 "Non-Destructive Inspection Methods and Techniques" (title?) used to be available on-line... it was incredibly detailed and might answer most of Your basic NDI questions (just about every type USAF NDI was "in-the-book"). I just checked... the T.O. appears to be behind a USAF firewall, now. The old versions are fairly large [8.5Mb], so attaching it is not an option for me. Perhaps someone has a copy...?

Personal NOTE.

I have lived my engineering career by "trust, but verify".

"Verify" can be a great way to get a "field education"... engineering and hands-on... and help sharpen people skills, too.

NEVER forget that Your NDI tech NAS410 level III has worked hard/long to attain their rating. There comes a point when You either "trust" their judgment/skill set [has done well in the past]... or distrust them [for whatever-reason].

CAUTION. I learned a long time ago that personalities do NOT necessarily determine skills/abilities. There were some folks [name a skill] that just drove me up a wall for one reason or the other... but I learned to fully trust. Others I liked working with them, but would pull a real boner occasionally... leaving me shaking my head... and sadder but wiser.

Regards, Wil Taylor

 

[WKTaylor]

cjohnson0

Ahhh... Your 3-level finally spit-out the real problem:

"... too large for our facilities."

I can't tell you how many times I have faced this same issue on every thing from cleaning, to stripping, to finishing, to IVD, to heat treatment, to forming, to you-name-it process....
"... too large for our facilities."

Gaaaaaaaaa

Regards, Wil Taylor