Although I'm not certified in any NDE method (my choice) there are positive benefits to having such a certification. There are also loads of negatives, depending on your perspective. In order to get a Level II cert, you need a combination of education, and experience. Basically, it's the experience issue that I am referring to as a "negative" that is, you must do your time as a Level I before progressing to a Level II. Most employers have little or no use for Level I certification because there are an abundance of Level II technicians. Also, in my particular instance, the only place I would use PT is where an MT would be impractical such as on austenitic stainless steels. In my experience, if you are interested in pursuing an NDE method, I would say the most bang for the buck so to speak would be Ultrasonic (UT). Well, I'm sure there'll be many technicians, far more qualified than myself who will have different opinions, but there's my opinion!
Check out ASNT's SNT-TC-1a certification "recommended practice". High school diploma students need 4 hours of training for Level I PT and 8 hours for Level II PT. College with at least two years engineering or science study with passing grades need 4 hour for Level I PT and 4 hours for Level II PT. Training and experience may need to be more extensive depending on your company's written procedures, but this is the min. recommended by ASNT.
PT has it's advantages, but in Structural applications there are more effective means of NDT. Automotive machine shops use alot of PT and MT because of the cost of the equipment is fairly inexpensive compared to UT or RT. The crack has to be open to the surface for PT to work, and not all cracks are opened to the surface.
Some thoughts for you to consider,
John Wright
We do some PT. As already mentioned, PT works good for non-magnetic metals like stainless and aluminum. And it is relatively easy to do and customers who may not know much about NDE can easily understand PT.
What I don't like about it is all the mess involved; seems like no matter how hard you try, you're gonna get it on you. Also, I've had a situation where PT showed nothing but MT showed cracks like a flashlight in the dark. This was a forged gear where PT had already been done, a crack was ground, and PT done again to see if the grinding was sufficient. Apparently, the penetrant had hardened and closed up the crack or something like that, but I didn't do the initial testing so I don't know if that was done correctly.
I think PT can be a good process when used right, but personally, I find MT to be cleaner, quicker, and easier for most of what I do. I can't compare it with UT because I have no training in that, other than what I've witnessed.
CHGuilford
I'll agree with the staining issue, I guess you just haven't done it right unless you go home with it all over you. The developer isn't bad but the dye gets on everything and you have to wear it off because it won't wash off.
Terribly stained,
John Wright
Oh, sorry guy's......my reference to UT was strictly in the sense of employment or employability ~ and had nothing to do with positive aspects of the methodology! The other comments made by these guy's I fully agree with. PT is a very easy process to learn, relatively inexpensive, but messy and only reveals surface indications.
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