Talk:Nondestructive testing

Irrelevant websites

I removed the link to NDT.org.ua - Information Portal of NDT and TD. The website is entirely in Russian. I am also not sure what TD means. User SmArt, please explain the relevance. Perhaps the link would be more useful on Russian Wikipedia.

DavidMack 14:18, 11 October 2006 (UTC)

82.163.171.137 keeps inserting links from John Drury and a UK company called Silverwing. These links are already included under the relevant topics (Magnetic flux leakage and Ultrasonic testing. They do not make sense on this page or under the heading NDT Published Journals, so I removed them.

DavidMack 21:34, 13 October 2006 (UTC)

Statistics

This is not a statistical debate forum.

To NDT Guru:

Of course, it's not a statistical debate forum. But it is a discussion, so please quit deleting questions and comments. Math (that includes statistics and probability) is the heart of NDT and any science. Do the math and let the banter begin!

--Terrible Swede 01:03, 28 July 2006 (UTC)

Reliability not defined, expected utility varies with user

November 26, 2005

In the past few days, I've revised the text to address issues that I believe to be quite important. The pre-revision text did not address the fact that probabilities necessary to the computation of a defect detection test's expected utility are unavailable. Also, it did not address the fact that the expected utility of a defect detection test is dependent upon user's utilities, which vary by user. A result of both facts is that it is impossible to state whether individual defect detection tests are useful or not-useful; the prior text implied that they are useful. I've also edited the text of past contributors in an attempt at making them more concise and clearer.

Terry Oldberg http://www.oldberg.biz

---

03MAR2006

Mr. Oldberg:

Why don't you use the traditional terms of binomial probability distribution: success (S) and failure (F); instead of OK/not_OK?

--Terrible Swede 18:40, 3 March 2006 (UTC)

---

Terrible Swede: Thanks for taking the time to discuss my contribution. From a mathematical perspective, any pair of symbols works. However, the semantics are also important. Nondestructive testing is a measuring process. It seems to me that the property of a part being measured is its all rightness and not its successfulness. Very little of the literature of nondestructive testing deals with its reliability and this results in an absence of terminological norms. In writing my portion of the article, I used as much of the terminology of diagnostic testing in medicine as possible. In medicine, however, the property of the human being tested is healthfulness, but healthfulness isn't a property of a part so I used all rightness (OK is synonymous with all right, not OK with not all right). By the way, the field of defect detection testing has not yet gotten around to defining what is measured. Thus, its understandable that in writing about its reliability one has to invent names for the values of the binary variable that is being measured.Terry Oldberg 00:49, 4 March 2006 (UTC)

03MAR2006

Mr. Oldberg:

Also, if you have determined to use the terms "true positive", "true negative", "false positive", and "false negative", which I would tend to use and are good terms, wouldn't you now need to use a multinomial probability distribution instead a binomial prob distribution?

--Terrible Swede 18:40, 3 March 2006 (UTC)

Terrible Swede: I'm unclear on the pertinence of the issue of the sample distributions. Please clarify your question.Terry Oldberg 20:43, 3 March 2006 (UTC)

Unnecessary focus in article

A large portion of this article seems to be devoted to the views of Mr. Oldberg. I do not have the background in nondestructive testing (my background is in math) to support or refute his claims, but it seems that having so much text about what appears to be a minority opinion is disingenuous. If I am wrong, and this is in fact a majority opinion within the field than feel free to contradict me. On the other hand, if I am right then perhaps the article should be rewritten to deemphasize this material, or at least point out that it is not widely accepted. For example, have these results been addressed anywhere in the statistics literature?

Irrelevant debate in article

I am an engineering physicist who has worked in the NDT field for 20 years, and I do not see the relevance of Mr. Oldberg's contribution. It seems to me that the primary purpose of this article and linked articles should be to explain the various methods of nondestructive testing (NDT). Probability of detection (POD) is an important area of study in NDT, but Mr. Oldberg has concentrated on one very esoteric aspect of POD and has not made an effort to clarify the issue or where his ideas fit in to the big scheme of things.

Davidmack 19:32, 25 July 2006 (UTC)

---

Actually, having read the paper I now have a question for Mr. Oldberg. In your paper, the following two sentences appear:

1) "If a "defect" had an indication within 3 inches of it, he assigned it to a true positive. Otherwise, he assigned it to a false negative."

OK, so we take all the defects, and call them either true positives or false negatives.

2) "However, Bradley's rule of evidence produces a conflict with this assumption. It assigns every "defect" to a true positive if it is within 3 inches of an indication. The same rule assigns every such "defect" to a false negative also. Let us examine the consequences of this ambiguity."

This appears to contradict the previous statement. It also forms the crux of the following argument. How is it that the above way of counting defects assigns defects to two categories simultaneously?

In my understanding of the above procedure, the relative frequency of defects is just 1 (as all trials are counted as defects of one sort or another). The probability of detection is then estimated as n_tp/(n_tp + n_fn), which makes sense to me.

Can you please explain statement (2) further?

(Note: I am not saying that what you've said is incorrect--I legitimately would like to know what you mean. I certainly agree with you that some of the measurements sound dubious from the way you have described them.)

---

Dear anonymous reader

Thank you for giving me the opportunity to comment.

The necessity for assigning a defect to two mutually exclusive categories rather than one seems to be what you don't understand. Assigning an object to two mutually exclusive categories may sound wrong because this violates the principle of Aristotelian logic that is called the "excluded middle." Violations of the excluded middle are built into defect detection tests, including the one reviewed in my 1995 paper.

Imagine an inspection technology in which the inspector provides the X, Y and Z coordinate of a point inside each, purported defect. A rule is in place in this technology which states that a defect is detected if one or more of these points lie inside it. In this case, each defect is either detected or it is not detected. The excluded middle is preserved and a probability of detection is defined. However, I'm not aware of a single defect detection test that operates in this manner. In particular, the test of pressurized water reactor steam generator tubes that is reviewed in my 1995 paper doesn't operate in this manner.

Now imagine that the point is expanded into a spherical region. As it expands in radius, it comes to intersect sound material plus many defects. Neither a single defect nor a single region of sound material is being detected. Rather, they are all being detected simultaneously. In this way, the law of the excluded middle is violated. Probability theory, which assumes the excluded middle, is also violated. This example captures the portion of the content of my paper which is under discussion.

Your proposal for assigning the ratio n_tp/(n_tp + n_fn) to a "probability of detection" fails because your "probability" is not a probability. Probability theory assumes the excluded middle but the test violates the excluded middle by its design.

The "pseudoprobability" with which I replaced probability in reworking the statistics produced by the study of Bradley et al copes with this situation by mimicking the one-to-many relation from detections to detected defects by assigning individual defects to the two categories of false positives and true negatives. A simple way of putting this is that one knows that a defect has been detected but doesn't know which. Pseudoprobability theory is an inadequate response to a incompetently designed technology. The proper response would be for the tests to be redesigned to preserve the excluded middle. The folks who control the content of nuclear reactor inspection technology have proved stoutly resistent to this course for a period of more than 20 years. That a misuse of statistical ideas and terminology is ubiquitous in the field of defect detection testing may be associated with this phenomenon. Competent design has been replaced by fallacious statistical reasoning. --Terry Oldberg 17:16, 19 July 2006 (UTC)

Removal of Text

I have mainly removed the section on statistics because it does not represent a neutral point of view: it engages in debate and argument, contrary to Wiki policy that "Debates are described, represented, and characterized, but not engaged in." The contributor of that section references his own papers. One subsection begins "Oldberg and Christensen (1995) and Oldberg (2005) report that ...", whereas "report" is listed as a word to avoid because it "bestows a sense of impartiality on a source." Perhaps the original contributor could submit a revised, more neutral version.

DavidMack 23:19, 12 January 2007 (UTC)

Garbling of message on statistics

In the year and a half since I last participated, the message on the anomalous statistics of NDT has become garbled beyond recognition. The message should be that defect detection tests fail to define statistical populations, thus failing to provide the basis for establishing their reliability. This message is spelled out in several peer reviewed articles, none of them challenged in the peer reviewed literature. If I hear no objections, I'll ungarble the text. If anyone wishes to discuss the technical merits, please contact me at 650-941-0533 or terry_oldberg@yahoo.com. Please be sure to contact me before regarbling the message.

Terry Oldberg, BME, MSE, MSEE, PE Nuclear Engineer —Preceding unsigned comment added by 171.66.222.156 (talk) 00:07, 31 October 2007 (UTC)

Removing the photo from NDT page

[I have taken the liberty of placing Plenumchamber's message to me on the talk page. DavidMack]

Hi, I see that you have removed my photo that I have taken in my NDT shop indicating that it is a commercial photo. I do not understand your point of view. For example is it a commercial photo if you put an Airbus a/c photo in an article? I have installed the photo in order to give the readers an idea about an test tool. As I have no relations with GE other than being an user, I have no purpose such as doing advertaisement of a company or product. Thanks in advance for your answer back.--Plenumchamber 11:50, 22 June 2007 (UTC)

Plenumchamber, thanks for explaining your motives, which I understand were not to advertise. And we do need pictures on this article. To me the picture [1] appears commercial because it only shows an instrument with a blank screen and gives the model name. It does not give any hint as to what the instrument does or how it relates to NDT. Do you have any pictures of data or of a technician using an instrument? That way the emphasis is on NDT. We also don't want companies following suit and putting up their instruments. Wiki is quite an advertising magnet. That said, if you want to put the picture back, I won't remove it, and sorry for the inconvenience. — DavidMack 15:13, 22 June 2007 (UTC)

Thanks for the expl. I will not put back the picture back cause I understand and share your resons, I will try to create a better photo while performing a test action. Thank you.--Plenumchamber 09:13, 25 June 2007 (UTC)

Thanks for the excellent photos. I hope you approve of the editing I did on the captions. — DavidMack 17:25, 28 June 2007 (UTC)

Thanks for the edits, now it is better--Plenumchamber 07:43, 2 July 2007 (UTC)

Link clean-up

We got caught. Too many links. Apparently Wikipedia is not supposed to be a repository of links. We should link only to 'further reading type material', i.e. "neutral and accurate material that cannot be integrated into the Wikipedia article due to ... amount of detail." So I removed most of our little link farm. I hope everyone is agreeable to this. — DavidMack 19:01, 26 June 2007 (UTC)

Someone added a link to a research institute, so I put back the original list of research NDE institutes. If anyone complains that they are commercial, they'll have to go. — DavidMack 16:51, 24 September 2007 (UTC)

Microwave based NDT

A lot has happened over the past decade in the domain of microwave based NDT - for applications such as cancer detection (Susan C. Hagness, U. of Wisconsin, et al) and fault detection in concrete. doesn't that merit mention here? 220.225.214.2 (talk) 09:47, 28 February 2008 (UTC)

Rewrite: Abstract

I will be re-writing most of this article for a university project concerning the instruction of NDT. Changes will primarily be grammatical or prose-based edits to improve readability and / or instructive clarity. Since this may be a big process, I will edit one section at a time - beginning with a much-needed article header / abstract. Please limit your discussion of the abstract to this thread.

Thank you!

Tythos Eternal 02:41, 23 January 2009 (UTC) —Preceding unsigned comment added by TythosEternal (talk • contribs)

Rewrite: 'Need for NDT'

I will be re-writing the section 'Need for NDT', replacing it with two sections: 'Background and Principles', and 'Applied NDT Examples'. Please limit discussion of these changes to this thread.

Thank you!

Tythos Eternal 17:58, 27 January 2009 (UTC) —Preceding unsigned comment added by TythosEternal (talk • contribs)

Background and Principles

Recent changes to this section imply that the original content was too vague and / or abstract. However, the new content is a paraphrase of the abstract at the beginning of the article. I think the 'Background' section should give the theory underlying and unifying NDT techniques, thereby developing the general outline given in the abstract. (See my previous edit for details.) Your feedback? Tythos Eternal (talk) 20:49, 28 January 2009 (UTC)

I deleted the text because it was quite obscure and irrelevant to the subject. It would likely put the casual browser or even the interested reader off the subject. If it must go in, put it at the end and not at the beginning. I use NDT methods regularly myself, and find that students and clients do need a general source without too much theory or obfuscation. Peterlewis (talk) 22:18, 28 January 2009 (UTC)

Almost the entire article is obscure and irrelevant to the subject. It is an article about a physical testing method, but it's written in completely abstract prose. A nail can be physically described, and that physical description, plus an image belongs in an encyclopedia, but this vague prose about measuring inputs and outputs will not make a reader understand that you run an ultrasonic transducer over a weld, sending sound through the metal, gathering sound back, and reading the result of the interaction of the sound waves with the weld on a screen.

Also, you do disassemble systems for NDT. In fact, a lot of NDT is pre-service, as in welding inspection and construction inspection. You test structural welds, turbine blades, nuclear reactor vessels as the system is being constructed. After the power plant or paper mill or pumping station has been constructed you do in-service inspections, often disassembling parts of the system for the inspection, then reassembling. Yes, the system or component is not sacrificed or damaged, but systems can be disassembled without doing either. That's how they're repaired in fact when components are found to be bad: you take out a bad part and put in a good one.

The pre-service inspection of a nuclear power plant involves, for example, the inspection of all welds on piperacks for conduits for cooling water, before the pipeline is installed, reactor vessel welds as the reactor vessel is being assembled, and heat exchanger tubes for both the hot and cold sides once the heat exchanger is installed. The in-service inspection will, on the other hand, be limited to critical components often using robotic systems, and, omits some parts of the plant due to radioactivity.

I realize system is being used in the physics or chemical sense of the word, but, again, this is an encyclopedia article about something that exists in reality, not in idealiality. NDT is used to test materials, part, and components that exist, and this article is making it look like a science experiment in particle physics, when it's actually the application, not the intellectual exercise of theoretically discussing it. --69.226.103.13 (talk) 08:01, 21 June 2009 (UTC)

"NDT involves comparing a known input to a measured output and comparing to a known model - does not require the sacrifice of the physical system, as would be the case with disassembly, dissection, or failure testing. Such methods are known as Non-Destructive Testing techniques. Because the physical system does not need to be sacrificed or damaged for NDT tests, such techniques are valued for saving time and money. On the other hand, NDT methods do not always reveal hidden defects, and skill is usually needed in interpreting the results. Such NDT methods are important in litigation because the material evidence is preserved intact."

Title

I always met this under the spelling : "Non Destructive Testing" rather than "Non-destructive Testing". Shouldn't we move the article to this ? RadXman (talk) 15:13, 26 June 2009 (UTC)

If you can find enough reliable sources that spell it a certain way, I think that would be adequate enough to move the page to a given name. Wizard191 (talk) 20:49, 26 June 2009 (UTC)

Hi,

When I search in google.book, I get 3334 hits for "Nondestructive Testing" and 2780 for "Non[-]d/Destructive Testing". The alternative "spelling" is at each time suggested automatically by google.

It seems the words are more usually linked "non" and "destructive" than the contrary.

RadXman (talk) 06:35, 27 June 2009 (UTC)

Please see, WP:GOOGLE. Those results mean nothing; we need reliable sources. Wizard191 (talk) 18:14, 27 June 2009 (UTC)

Hi Wizard191,

You missed the points :-)

Googlebook lists most of the reliable sources that use one spelling or the other.

The results show that if both spellings are used, the current title is most used.

A reliable source focusing on the spelling of Nondestructive Testing and stating that one spelling is better than the other can hardly be found or is simply impossible to found.

So, nothing has to be changed, for sure. RadXman (talk) 07:09, 28 June 2009 (UTC)

I didn't follow that you were saying that the article didn't need to be moved before. Wizard191 (talk) 18:34, 28 June 2009 (UTC)

Hi. Sorry for the misunderstanding. My mistake. RadXman (talk) 19:25, 15 July 2009 (UTC)

It's all good! Wizard191 (talk) 19:33, 15 July 2009 (UTC)

NDT link

_{Copied and cleaned up from User_talk:Wizard191#NDT_link. Refers to this edit and its progeny. TRANSPORTERMAN (TALK) 18:19, 10 February 2010 (UTC) Cleanup 18:25, 10 February 2010 (UTC)}

hi, the link to the tutorial in non-destructive testing is not advertising. it's a tutorial on how to gauge thickness using ultrasonics. it's not promoting a product. —Preceding unsigned comment added by 208.48.226.130 (talk) 20:27, 9 February 2010 (UTC) It is not advertising, however it does not qualify for inclusion per WP:NOTHIOWTO and WP:ELNO point 1. Wizard191 (talk) 20:39, 9 February 2010 (UTC) is there a way for us to get a second opinion on this issue, because it seems like there are many such links on wikipedia. thanks. —Preceding unsigned comment added by 208.48.226.130 (talk) 21:25, 9 February 2010 (UTC) Sure, see WP:THIRD. Wizard191 (talk) 21:31, 9 February 2010 (UTC) my issue is that the WP:NOTHOWTO does not apply in this case because it refers to an article, and what i tried to post was an external link. in regards to WP:ELNO point 1, i don't understand what this means. what i was trying to post was just an external resource for people who want to gain a better understanding of ultrasonic thickness gauging, which is a common ndt method and seems very apt for people looking for more information. —Preceding unsigned comment added by 208.48.226.130 (talk) 13:54, 10 February 2010 (UTC) WP:NOT applies to Wikipedia as a whole, not just the text part of the article, but to all aspects of the article, therefore links to how-to information is not welcome. Wizard191 (talk) 13:57, 10 February 2010 (UTC) it states the following "Wikipedia articles should not read like: 1. Instruction manuals." this implies that tutorials and such are not allowed to be re-posted, and should not refer to a simple informational link at the bottom, as this would not cause the article to read like an instruction manual, how to guide, recipe, or tutorial. there are many such instances of this throughout wikipedia, such as Installation_(computer_programs) Nikon_D90 Ipod these all have external links to manuals, tutorials, or how to guides. --208.48.226.130 (talk) 14:17, 10 February 2010 (UTC) I'm sure you can find many more references to articles that have content against policy, however that doesn't make it right. If you disagree please open up a case at WP:THIRD. Wizard191 (talk) 14:35, 10 February 2010 (UTC)

Response to Third Opinion Request:

Disclaimers: I am responding to a third opinion request made at WP:3O. I have made no previous edits on Nondestructive testing and have no known association with the editors involved in this discussion. The third opinion process (FAQ) is informal and I have no special powers or authority apart from being a fresh pair of eyes. Third opinions are not tiebreakers and should not be "counted" in determining whether or not consensus has been reached. My personal standards for issuing third opinions can be viewed here.

Opinion: I'm not, frankly, a hard–core deletionist on external links and I might have a really difficult time deciding about this one if it was inserted in an article on ultrasonic thickness gauging (at least if there was some assurance that it's not spam), but it's not appropriate here for the reasons which have already been discussed in the foregoing discussion and also because it's simply too specific and detailed for this broader–topic article.

What's next: Once you've considered this opinion click here to see what happens next.—TRANSPORTERMAN (TALK) 18:55, 10 February 2010 (UTC)

oh well, i tried. but just a comment, if the "no manuals, how-tos, tutorials" rule applies in this instance, then it should go double for that GE picture with caption: "step 1: The UT probe is, etc., step 2:" --208.48.226.130 (talk) 19:05, 10 February 2010 (UTC)

why was my edit tagged possible conflicting information?

sorry, new to this, thanks. here is the link to the page with my revision on it: http://en.wikipedia.org/w/index.php?title=Nondestructive_testing&oldid=387587288

see also: optical interferometry. Thanks in advance! —Preceding unsigned comment added by Lumetrics (talk • contribs) 19:52, 14 October 2010 (UTC)

External links

I removed external links that appeared to be unrelated to the article; explanations and diffs are provided:

I removed one spam link and one off topic link both related to employment and career opportunities in the NDT field [2]. I removed links to commercial web sites, and recruitment sites because this is not really part of Wikipedia's intent or mission [3]. I also removed misleading links that claim to be sourced at U.S. Goverment sites when in fact these are linked to commercial web site [4].

I recieved a response on my talk page pertaining to these edits. Below is a copy of the conversation in progress: ---- Steve Quinn (talk) 03:18, 30 September 2011 (UTC)

Mr. Quinn,

Thank you for taking the time to keep the NDT page in Wikipedia up to date. However, please note that external links to the largest information sources for NDT information on the net are acceptable content as per Wikipedia:

"External links to commercial organizations are acceptable if they identify major organizations which are the topic of the article"

For example, ndtWiki.com is a commercial entity that you did not remove from the list, yet you removed other more relevant sources of information.

Sincerely,

David B

201.253.128.111 (talk) 12:26, 29 September 2011 (UTC)

First, I almost did remove ndtWiki.com but decided to think about it. That I did not remove it is not a rationale for restoring external links that might not belong in the article. Second, I doubt that links to recruiting sites, jobs, and classified adds are appropriate for an article on Wikipedia. Third, there were links claiming to link to U.S. government sites, but were linked to a commercial site instead. I don't know if these were restored, but hopefully not. It might be just as easy to link to the actual U.S. government sites. Thanks for your feedback. Hopefully we can reach an agreement as to what external links are relevant for this article. ---- Steve Quinn (talk) 01:01, 30 September 2011 (UTC)

It seems to me that the basic WP policy is clear enough. The comment quoted by David doesn't support including these links. The quote says "External links to commercial organizations are acceptable if they identify major organizations which are the topic of the article". I underlined the key element of concern. An external link to a commercial org is okay iff the organization itself is the topic of the article; such a link isn't acceptable if the organizaiton is a company involved in, related to, or providing information about, the topic of the article. Any link of the latter type violates WP:ELNO. I think that this point is a bit clearer when one reads the text on WP:ELNO which reads "Except for a link to an official page of the article's subject, one should generally avoid:...".

Anyway, I reviewed several of the links deleted by Steve and I completely agree with his assessment. That does not surprise me because there are very few times when an external link to a commercial org will be acceptable in WP. FWIW, NDTwiki.com is a bit different simply because it's a community wiki about NDT (all info falls under CC-BY-SA and GNU FDL) and the commercial interest, if any, is not obvious at all. At the same time, the actual content is limited (the wiki appears to be new) so it may or may not warrant having a link to it. But it doesn't appear to be an outright violation of WP:ELNO. — RB Ostrum. 13:27, 3 October 2011 (UTC)

NDT.net and NDT.org are by far the most popular and largest repositories of information about nondestructive testing on the net for information including technical papers, nondestructive questions and answers, products and services needed by NDT professionals, and career information and have been for almost fifteen years. Since this information in its entirety is relevant to the community, and does not violate the terms of use for wikipedia, it is obvious that the motivation behind these deletions is to effect personal preference over the will of the NDT community for the purpose of personal gain. The NDT community, as a whole, has made it clear that these destinations are relevant, useful, and necessary based on traffic alone, so the fact that it is not a violation of the TOS further reinforces the fact that the edits to delete these external links are motivated by something other than desire to improve the quality of the nondestructive testing page. Further, this is similar to the information contained in newly developed NDTwiki, so the argument that the information is not relevant is clearly prejudicial.— Preceding unsigned comment added by Brtinc (talk • contribs) 15:26, 15 October 2011 (UTC)

Neither recruitment nor the NTD Online Journal are the topic of the article. What WP:EL means is if the topic of the article is, e.g., Coca-Cola, then it's acceptable to link to http://www.coca-cola.com. NTD.net nor NDT.org are the "official websites" of non-destructive testing. They are spamlinks. Headbomb {talk / contribs / physics / books} 18:22, 15 October 2011 (UTC)

This is not true. NDT.net and NDT.org are the original repositories of relevant information for NDT (not NTD) and neither runs on thanks. They are relevant, contain useful information to people who actually need to learn how to do a job, and also find one. Headbomb has been altering the external links of wikipedia to gain favor for wikipedia, which actually is a scaper site and which he has relations with. Before removing content, it must be verified as non relevant and against the TOS, of which these links are neither. BTW, Mr. Headbomb left the link ndt-ed.org intact even though it takes money for advertising, so I'm not sure what the criteria is for removal here.— Preceding unsigned comment added by Brtinc (talk • contribs) 01:34, 17 October 2011 (UTC)

Except that Wikipedia is not the place to "help people find jobs". That's exactly what WP:SPAMLINKS are, nor should we care that these commercial websites "do not run on thanks", per WP:PROMOTE. Since you created NDT.org, I assume you're the affiliate with that website, placing you knee-deep in a conflict of interest. Headbomb {talk / contribs / physics / books} 01:39, 17 October 2011 (UTC)

I would have to concur hence why I removed SimplyNDT.com. I wasn't the only one with the same thought, as it was removed previously, but keeps getting put back in. If people were looking for a job, just google it and you'll find the website. Bernoullies (talk) 06:29, 2 December 2011 (UTC)

So the site is banned because one of the features it provides is the feature that the professionals in the industry demand the most? This in itself certainly doesn't violate any wikipedia TOS. Still haven't identified that this is a violation of the wikipedia TOS. — Preceding unsigned comment added by Brtinc (talk • contribs) 01:55, 17 October 2011 (UTC)

ASNT, NDT.NET (the main repository of NDT research papers) and NDT-ED.ORG (complete, organized and free NDT training materila) are perfectly acceptable links to important information which supplement the current article. They are not spam links, please don't delete them. SV1XV (talk) 11:45, 17 October 2011 (UTC)

Underwater diving?

Why does this article have a link to the Underwater Diving portal? --Kierkkadon ^{talk/contribs} 15:05, 28 January 2013 (UTC)

Article has two "Applications" sections.

Why? 172.12.225.38 (talk) 21:40, 29 October 2014 (UTC)

Because Wikipedia articles grow by accretion. Trimmed the extra section and merged it. --Wtshymanski (talk) 19:22, 30 October 2014 (UTC)