Folks, I am just curious what UT test devices you are using? Do you have it calibrated to a National standard? Is the person who uses the device in your organization certified to perform such work or are you just winging it and hope you get it right? These devices appear simple enough to use without a significant amount of training, but what are your thoughts. Does the FRA enforce the use of a national standard for the test device and the user?

Thanks,
Mike Tillger

UT tools can be very simple or very complicated, with a lot of variables in between.

A "proper" UT test is conducted by a trained technician, using whatever device that technician desires, for the test requested. The results are often certified by the technician, or the company he works for, and given to the customer for a fee. The results are only as good as the technician and the device. The fee can be large.

On the other hand, the UT test can be conducted by a layman, using a simple and cheap machine. The results of the test can be quite informative and useful, for much less cost.

A basic thickness tester can be purchased for a little as $100. Several models are in the $100-$250 range, and these will fairly accurately show metal thickness for a basic boiler survey. They have a test surface that is part of the machine, where the probe can be calibrated by the user. Very simple.

I work as a boiler inspector, and use one of the simple machines. I am self-taught, and can perform tests to satisfy my needs. If there is question, either from an owner/user or myself, then I call in the professionals.

Bottom line is that anyone can use the simple machines for a basic survey. If that survey shows areas of concern, then call the professionals.

I'm not aware of any specific wording regarding UT standard calibration requirements in FRA guidelines.

Mike,

A few years ago, I learned that even when a professional is hired to do UT, I still had to be involved in the process. When we removed the insulation from a chemical storage tank, we discovered significant corrosion on the outside of the vessel. The decision was made to replace the tank, and a professional firm was contracted to provide the UT readings that were needed to convince the corporate office. When I received the report, I was surprised to see that the tank was still in good, useable, condition. Being skeptical, I went out to take another look. What I discovered was that the technician had laid out the grid in such a way that the readings were taken from uncorroded, or less corroded, areas where less surface preparation was required.

It’s like the story of the guy who lost his watch one night, and then walked down to the corner to look for it because the light was better there.

Bruce E. Babcock

Now, here's a question that I have. Working in the oil heat industry, we run into leaking oil tanks on a regular basis. Most are in similar condition to what Bruce described, but corroded from the inside out in most cases (could differ with outside tanks, depending on where they are, yada yada). So, assuming we question the integrity of the tank, could it be UT'ed in a similar manner to a boiler to determine the thickness of the material?

My experience mirrors Bruce's. I learned by working with somebody who knew what he was doing and taught me.

Steel tanks are steel tanks whether they are used as pressure vessels or for storage. Thickness of steel is thickness of steel. I suppose it is theoretically possible that if you have a steel tank holding steel, it might not be able to tell the difference between the tank and the steel within it, but that's an unlikely situation.

My old Krautkramer instrument is calibratable for different metals, bit I've never used it for anything but steel. I've run into trouble with bad cords or dirty probes, both easily repaired. Weak batteries are also easy to deal with on site as they occur. There's a calibrating block of .250 built into the unit for frequent and fast calibration checks, but for more accuracy you might get calibrating blocks made to something close to the thickness of what you are testing.

dave

My impression is that a normal UT will read to the first material change, the first reflection. So it should ignore rust or the stored contents of the tank.

They make UT machines specifically for testing the thickness of a coating (paint, etc). I think I've seen more complex machines that can ping through multiple layers and separate them out

What I have heard to calibrate the machine is to test a spot on the (boiler, etc) where you can get a micrometer on it and double check it.

The best UT machines have the capability to distinguish between steel and corrosion. Some can even show that information on a screen.

If you are going to use a cheap one on a boiler shell, test from both sides at the same location. That should also work for the roof sheet and crown sheet, but could be a non-starter for side sheets, throat sheets, backheads, and wrappers, where you can't get to both sides.

It may also be prudent to have the testing done by pros. People who do NDE for a living and are properly trained and credentialed are pricey, but they should also be a bit more impartial than people whose real bread and butter comes primarily from building and selling new boilers.

Buyer beware.

Seems to me that if you are doing UT for a1472 day inspection it would be a good idea to document the machine, method (as in ASTM) and the qualifications or the operator. When the FRA reviews the Form 4, they DO look to see the source of the data used in the calculations. They like to see that the data was collected by a qualified person.

A few observations and comments regarding the CFR (Part 230) and performing inspections.

1.) You will notice in the CFR that it does not require any specific level or training for the NDE examiner. This was specifically written this way as the rule is not intended to impose a financial burden on the operator.

2.) Examiners are normally known as NDE Level I, II or III. If you hire a professional, you will seek and want a Level II or higher.

3.) Professionals make mistakes too. Normally they carry manufactured calibrating blocks which have a density higher than historic boiler steel. At Wasatch, we actually had made for us a set of calibrating blocks made of historic boiler steel(we had to have them tested and certified as well). Be careful, a standard calibrating block, off the shelf will NOT measure the same as a piece of historic boiler steel.

4.) Find a location on your boiler where you can physically measure a spot on the boiler and then do a UT test in the same area to confirm calibration. I like doing a tube sheet as the steel is boiler grade steel, you can clean a spot off on both sides and you can then check the thickness with a caliper or depth gauge or other means.

5.) We could debate proper practices for doing an inspection(again purposely not included in the CFR for specific reasons).....but that needs to be another thread. Suffice to say, the purpose of the test is to find the weakest link.....not to find out how good the boiler is. You can look at a boiler and find great stuff. The objective of the test and the new 1472 day rule is to find the weak link and correct it. Too often, I look at results and ask....."Did you look at this and that...?" "No....we found some great stuff and think it is all OK......"

On almost every boiler......you can normally find the weakest link in the same general areas and most of the time, we tend to overlook these areas in the industry when the tests/inspections are done.

Most kindly,

JohnE.

Just looking for the weakest link troubles me. If you have a leaky boat, logic suggests that only patching the biggest hole is not the best way to stay afloat. Shouldn't all sub-code deficiencies be addressed?

What is wrong with my logic?

Nothing...and sometimes the weakest link is still plenty strong enough to comply with the calculated requirements, and some times the weakest link is just one problem that needs to be repaired along with a lot of other stronger but too weak links. Remember, even a newly built boiler will have one weakest part.

I think what John meant and what he wrote were two different things....he knows his stuff.

dave

Hi Mike:
Valley Railroad uses a "StressTel T-MIKE" with a 3/8" dia. transducer and a 1/4 to 1 inch store bought step block.
There being no National Standard, we sent ours in periodicly for calibration.
Although none of us here have had any training on the devise, we check its operation prior to each use and occationally during the day with the step blocks and/or when we find an anomaly.
It is true that different steels will have different velocities, but the variation is so imperceptable as to be irrelevant for our purposes (if you are so close to condemable that .001" is an issue, you already have a problem).
During the ESC/FRA re-write of 49CFR Part 230, Form 4, these issues were discussed at length, and since we worked on the basis unanimous consensus, I can say that we didn't feel that the lack of certification (devise or operator) was an issue.
Why?
Because someone must sign the Form 4 and take ownership, responcibilty and liablity for the dimensions and calculations therein.
J.David

One more comment: in addtion to the creation of the Form 4, we use the UT devise to measure the thickness of the dry pipe and arch tubes (if equipped) for filling out the Form 3 Annual Inspection Report. JDC

The weakest LINKS.

Sometimes our desire to see a locomotive run overcomes our ability to look for the weakest link(s) in the boiler. Weak links are not leaks.....they are separate issues. Two courses of a boiler that are joined by rivets and each 3/4 of an inch thick make a great joint.....even if they leak. Stay bolts that leak are not necessarily a weak link.

We often see these as very VISIBLE issues when we look at a boiler. My comment leads all of us to consider the fact that often....(too often) we overlook the weak link(s) as we simply are not looking for them.....as they did not scream out to us as a visual item we could catch, so we inadvertently miss them. The purpose of the UT inspection is to help us see with different eyes. However, if we fail to use the eye to look at the potential weak link(s) how can we expect to see it (them)?

Are you using UT to complete a requirement of the CFR or are you looking for the weak link....not the leak? It is an industry question that needs to be asked and enforced as we have new people coming into the industry and studying the "step by step" processes, without learning or applying the reasoning behind them. One last time; Are we doing UT to complete a Form 4 or are we doing it to ensure the safety of the boiler? I am afraid to tell you that some do it for separate and not equal reasons.

J. David has opened the door here.....there is a lot about the CFR that had to do with ALLOWING us to find the weak link, but not overly dictating HOW you (we) found it or addressed it. The CFR leaves plenty of room to interpret and apply on an individual basis and be as dedicated or not to the process.

Kindly,