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Up Topic Welding Industry / Inspection & Qualification / AWS D1.5 UT inspection
- - By kazu (*) Date 06-15-2007 12:54
I am japanese inspecter. Now, I study AWS spec.
I have questions about angle beam.
At first, I think IIW reference block(1.5 hole) is very high sensitivity (more than ASME).
from 50 to 70 FSH?
second, Scanning levels is Zero Reference +20, 25 db (change in Sound Path)?
I cannot scanning, becase there is high noise.
Please teach me about AWS (UT inspection).
Parent - - By jwright650 (*****) Date 06-15-2007 12:59
What brand UT machine are you using? I'm using a Krautkramer USN 58 and it doesn't seem to have that problem(noise/grass) unless you go down to a 1" scale or less. What thickness are you scanning? What scale are you using? How rough is the surface of the parts that you are inspecting?
Parent - - By kazu (*) Date 06-15-2007 13:08
thanks.
I am using a EPOCH4.
Material thicness is 100mm (4 in.).
Surface is as ground.
I think AWS spec. is very high sensitivity.
Parent - - By jwright650 (*****) Date 06-15-2007 13:30
With 4" material you should not have problems with noise unless the material is very grainy.
Parent - - By kazu (*) Date 06-15-2007 13:44
I see.
Is Scanning level more than Calibration level + 20db?
and I would like to understand Table UT Acceptance Rejection Criteria.
Parent - - By jwright650 (*****) Date 06-15-2007 13:59 Edited 06-15-2007 14:09
What you do is set your reference line when calibrating your machine and then add the decibels required by code for the scanning level(+20 or whatever the code says the minimum scanning level is).

Has your wedge become scratched or become very rough, or has the wedge been dropped?? That could also cause you to see alot of noise when scanning at high levels. Also, make certain there is no air between your crystal and wedge.<---bad couple to the wegde usually reduces the amount of sound going into tthe part though, so that might not be your problem.

I use vasoline to couple the crystal to the wedge and then calibrate, get my reference level set, then add the required gain to get to the scanning level.

edit: after you start scanning and run into something that needs to be evaluated, you reduce the amount of gain until your signal is completely visible on the screen, position the transducer so that you peak up and get the highest signal possible, then reduce your gain until the peak of your signal is just barely breaking your gate(reference line). At this point take note of your decibel level and record it. Now figure your sound path and attenuation, so that you can subtract the attenuation out. Now that you have done this, the number you now have is your indication level. Take that number and look at your acceptance/rejection table in your code book and see where it is in relation to the table. Be sure to follow the chart correctly for the thickness, angle used, etc....
Parent - - By kazu (*) Date 06-15-2007 14:16
Thanks you.
Scanning level chages by Sound Path.

>5 in. throught 10 in. : +35db etc...


I feel high.
And I do not understand Acceptance Criteria.
About Weld Thickness and Search Unit Angle vs. Flaw Severity Class.
Parent - - By jwright650 (*****) Date 06-15-2007 14:46 Edited 06-15-2007 14:48
I don't have a copy of D1.5 in front of me and it is different than the D1.1 that I'm looking at.
Make sure you are using the correct Acceptance/Rejection chart for your application...one is statically loaded connections, the other is cyclically loaded connections.

I'm looking at Table 6.3 in D1.1.....

>2 1/2" thick material through 4" thick material


find your angle, where does your indication rating hit in that column?

ie. 70* column
+6 and up is a Class "D" Severity Rating
+4 through +5 is a Class "C" Severity rating
+2 through +3 is a Class "B" Severity rating
+1 or lower is a Class "A" Severity rating

There are also notes below the Table regarding the lengths of these Classes of disconituities to determine acceptance or rejection.
Parent - - By kazu (*) Date 06-15-2007 23:02
Thanks.
I know the this table (+6 and up is a Class "D" Severity Rating etc...).
But I can not use it.
Because, I don't understand that why "large + number" is Class D (minor flaws).
"small + number" is classA (large flaws).
Is "Indication Rating, d" equal to +X db?
Parent - By cepennington (*) Date 06-16-2007 18:21
Just for explanation purposes, I will not include attenuation factors.

The larger number is a smaller flaw because the numbers come from your reference. If your reference is 56 db, and the indication is a +10, then it means that the signal size of that indication matches the signal size (screen height) of your reference with a gain of 10 db. That sounds confusing.

Ok, if your reference is 56db with a screen height of 80%. And the indication reaches a screen height of 80% at 66 db, then it would be a +10. Now with that said, if the indication reached a screen height of 80% at a db level of say 46, it would be a -10. Meaning, the smaller reflector would take more sound to reach the same screen height. The larger reflector would take less sound to reach a screen height of 80%.

You get this by using the formula a-b-c=d which is designed to be used with the attenuation factor. The attenuation factor is what AWS uses in lieu of a DAC curve.

Hope this helps
Parent - - By CWI555 (*****) Date 06-17-2007 05:59
It has to be keep in mind that the standard AWS exam is reliant on decibel response.
For acceptance, the final number of the a-b-c=D the acceptance goes in descending order. I.E. a rating of +10 is less severe than a rating of 0 or -5.

I suggest before you begin trying to apply the testing procedures, you first get familiar with the equipment qualification procedures.

What you described as to much noise could be an internal reflector problem as others have mentioned to you.
To check for internal reflectors in the transducer shoe set calibrate per normal calibration procedure setting the reference level B. then remove the transducer from the block, wipe it dry, and while keeping the transducer free of any contact with anything, increase your DB's by 20. The screen area beyond 12 mm [1/2 in.] sound
path and above reference level height shall be free of any indication. if it is not, something is wrong.

Vertical linearity is different from the ASME method. AWS holds a tighter tolerance for a reason. It's depending on decibel response for acceptance or rejection rather than percentages of DAC.

Again, it's highly advisable and I believe absolutely necessary to be familiar with the rules of AWS code before trying to apply them.

The acceptance criteria uses the A-B-C=D rule for instruments with gain in decibles and for instruments with gain in attenuation it's B-A-C=D.
The majority of units are the abc variant. The following is a break down of that formula.

A= indication level. When an indication is found, find the highest response, then drop it to reference level. The resulting reading for DB is your indication level.
(this is why your scanning level is set hot. When you do find an indication, the reduction to reference yields a response correlation to the zero reference level B)
If it's a small indication/reflector the resulting number will require more DB to bring it to reference, with a resulting higher number plugged into the ABC formula. A large indication/reflector is found (larger than the response from the 1.5mm IIW block hole, the response DB will be less than your reference level B number which will equate to a more severe discontinuity rating.
It is also important to remember that your scanning levels as found in table 6.4 are in sound path not in thickness (the same for table 6.3). Table 6.2 has to be taken into account as well. For a 4" (100mm)  butt weld, either no 6 or 7 plan is used. Using # 6 the face A is ground flush. The first scan is at 70 degrees for the first 1" or 25mm, the middle half (from 25mm to 75mm) is scanned again from face A with 70 degrees, and the final scan is the last quarter or 75 to 100mm is scanned with a 60 degree wedge.
(general notes table 6.2 where possible, all examinations shall be made from face A and in leg 1, unless otherwise specified in this table.)

for scan 1 scanning level is ref max+ 19db.
for scan 2 scanning level is ref max+ 29db.
for scan 3 scanning level is ref max+ 29db.

B= zero reference level. Which is as of 2002 (do not have the last edition of D1.5 but I doubt it's changed) doesn't specify the level. I typically use 50% FSH for zero reference.

C= attenuation factor. This is derived by subtracting 25mm from the sound path, then multiplying the remainder by 2. round fractions less than half to the lower number, and fractions 1/2 or better to the next highest number. AWS defines attenuation as 2 db for every 25mm after the first 25mm. I.E. for 75mm sp 75-25=50mm 50mm/25mm=2 2x2 =4 db attenuation factor.

A hypothetical flaw in a 100mm thick butt weldment at 27mm down on scan one at 70 degree scan. It would yield a sound path/metal path of 80mm. It was found at scanning level (reference plus 19db). After proper sizing using the 6db drop method (25mm long), and finding maximum amplitude return, it's dropped until it's at reference level. For this instance the resulting DB reading will be 50db. (indication level A)
Reference level B was set at 50db.
The attenuation factor would be 80mm-25mm= 55mm 55/25=2.2 the remainder being less than .5 is rounded down to 2. (2x2db =4db)
This makes the attenuation fact C = 4db.
Apply A-B-C=D. For instance if A was 50, B was 50 and C was 4 then 50-50-4= an indication rating D of -4.

Going back to table 6.4 and the appropriate column for the thickness of weld (60mm through 100mm) the indication reading D is applied to the table.
A rating of -4 would make this a class B flaw.
This brings you to the general notes of table 6.4
It's a singular flaw, therefore none of the primary notes apply, then going to the class B acceptance criteria we find that the maximum length for a class B flaw is 20mm.
Since the flaw was 25mm it is rejectable per the rules of 02 D1.5.

If anyone of the Gurus of this forum have a different take on this please feel free to speak up.

Regards,
Gerald
Parent - - By kazu (*) Date 06-18-2007 16:45
Thank you.
Now I am gradually understanding about AWS.
However, I have new two questions.

1. I understood that scanning levels indicate "MAX value".
e.g. When Above Zero Reference is 14 db, Max is +14db.
That is, Scanning levels is +6 or +12db etc...
Is this OK?

2. Next, I must make "other approved UT reference blocks" (Type DS, RC SC) .
I would like to know dimensional tolelance, surface fishish etc...
Please teach me how to make a block.
Parent - By CWI555 (*****) Date 06-18-2007 18:43 Edited 06-18-2007 22:31
As for the blocks, the dimensions are given in D1.1 or D1.5. Be careful with the "other approved". For instints, the resolution check block is not allowed for setting reference, it's sole purpose in live is the required resolution check. In short be mindful of the difference between a qualification block, and a reference block.

Zero reference level is your cal off the 1.5mm hole in the IIW. The scanning sensitivity is the required additional DB. I.E. reference at 34db, scanning is +19db total is 53DB that is used to scan with.

Regards,
Gerald
Parent - - By CWI555 (*****) Date 06-18-2007 22:31
D1.5 02 figure 6.5A material is A709 gr. 250 or acoustically equivalent.
Finish is maximum 3 &#956;m rms.

The notes of 6.5a also apply to 6.5B
The information you need to have these blocks produced are listed in the referencing code.
Parent - - By kazu (*) Date 06-19-2007 04:30

>Zero reference level is your cal off the 1.5mm hole in the IIW. The scanning sensitivity is the required additional DB. I.E. reference at 34db, scanning is +19db total is 53DB that is used to scan with.


I tried to sensitivity calibration again.
Reference level "b" is 48db (I used EPOCH4 and WB70°, adjust FSH75%).
I add db for scan.
I could perform scanning at +19 db (total is 67 db).
However, in other case (Add +29 or +39db), I think that scanning is very difficult,
because these total db will be very high sensitivity.
I will be not able to distinguish flaw indication from this high sensitivity.
e.g. Set the low FSH ? (I think this idea is not enough)
Parent - - By CWI555 (*****) Date 06-19-2007 04:53
Don't know what to tell you then. To perform D1.5 inspection by the book you are required to use the specified scanning sensitivity.
Your reference DB doesn't sound right to me, and you could use 50%FSH instead of 75. What is your screen range?
Jwright650 has already asked that question with no response.
If your having the problem your describing with an Epoch 4 or equivelent scope, then there is a missing element in your response.
I've used an Epoch4 extensively, and have never had the problem your having.

Regards,
Gerald
Parent - - By kazu (*) Date 06-19-2007 05:22

>What scale are you using?
>What is your screen range?


I can not understand it.
Relationship between screen range and sensitivity.

plaese, teach me.
Parent - - By CWI555 (*****) Date 06-20-2007 01:19
Kazu,

I am trying to help, but if you don't know something as basic as screen range, Im not sure how I can help you. I am getting the impression your trying to use the auto trig functions and auto cal functions in the scope. For information, screen range = horizontal sweep = time line = distance = metal path = sweep range. All have been used synonymously to describe the same thing. 
Parent - By thcqci (***) Date 06-20-2007 12:10
I have been quiet until now because others looked like they were answering your questions well and I had nothing to add.  But, with all due respect, I would like to say that if you are doing UT as a certified Level II inspector (or equivalent) and you are having some trouble doing UT on a bridge, you should probably turn to your UT III for some assistance.  I would be concerned with thoroughness of the inspection with some of the questions.
Parent - - By jwright650 (*****) Date 06-20-2007 13:23 Edited 06-20-2007 16:58
Ok, lets back way up and get some very elementry UT fundamentals under your belt before we go any further.

Scale or Screen range. This is very important, if you are trying to determine where something is that you have found....if you don't know where your seeing, how will you be able to determine whether the indication is in the weld or simply the edge of a backing bar?

If you have your machine set for a 10" range, and you have an signal on the screen at 50% FSW (Full Screen Width), where is your signal?

(I won't confuse you with determining where in the part your signal is or which leg your in, for now, we'll talk about that later once we get some of this understood)

***edit: Sound path = %FSW times range

or in other words: range=10" x 50%FSW = 5" Sound Path***

answer = 5"

If you have your range set at 5" that same indication would show up on your screen at 100% FSW.

If you have your range set at 3" that same signal will be off the screen to the right so far that you won't even see it and would completely miss a flaw that could make the weld fail and hurt somebody.

Are you starting to see the importance of the setting the range yet?

The range has nothing to do with the sensitivity at all in this case.
Parent - - By kazu (*) Date 06-21-2007 08:54
Thank you very much. Thank you for taking time in explaining things well to me.
Parent - - By kazu (*) Date 08-23-2007 07:14
I don't understand abc formula.
Gain
a-b-c=d (gain)
Attenuation
b-a-c=d (attenuation)

When d (attenuation) is positive, d (gain) is negative?
For example, a=56, b=50, c=2
Gain : 56-50-2=4 ???
attenuation : 50-56-2=-6

Is UT acceptance-rejection criteria d (attenuation)?
Parent - By jwright650 (*****) Date 08-23-2007 11:12
Hi kazu,
The formula that you will use to figure your Indication Rating (d), totally depends on the UT instrument.

for UT Instruments with gain in dB use a-b-c=d <----I use this one because of my machine

for UT Instruments with attenuation in dB use b-a-c=d

You can find this in D1.1:2006 6.26.6.5, also see Annex M for more description of this formula on page 329(directly in the center of the page).
Parent - - By jwright650 (*****) Date 08-23-2007 11:28
kazu,
I just realized this question was entirely answered in great detail by CWI555 on 6/17/07.
Parent - - By kazu (*) Date 09-10-2007 06:18
Thank you. I always appreciate for your answer.
May I ask you a question?
Now, I would like to perform the Equipment Qualification (UT and MT).
I will carry it out in conformance with Equipment Qualification Procedures.
And, I will use AWS form.
After I examined Equipment, I sign the paper and only keep the it in a file?
For example, My boss approval the paper, I stick small certification on the Equipment.
Please teach me.
Parent - - By jwright650 (*****) Date 09-10-2007 12:41
kazu,
Your company really needs to hire a Level III UT guy to help you get your NDT program off the ground and running. Your company needs to develope and adopt some equipment calibration forms and then have your company Level III advise you and have more input so that you won't make simple mistakes or overlook obvious flaws. It really worries me that inspection is taking place without the help of a Level III UT. The ASNT has already set up this chain of command for UT operators and it works with AWS to assure that your company has competant inspectors in place. Please obtain a Level III.
Parent - - By hogan (****) Date 09-11-2007 15:37
i am asking you please to be teaching me asnt level III ut with much appreciation
Parent - By g32141 (**) Date 09-12-2007 04:24
Shame on you.
Parent - - By g32141 (**) Date 09-12-2007 04:22
If you are qualified to qualify the equipment then you can print whatever piece of paper you want and sign it.

Make sure you know what you are doing though.
Parent - - By kazu (*) Date 09-15-2007 05:02
Thank you very much.
Now, I am making sure of requirements.
MT : ASTM E709  20.Evaluation of System Performance/Sensitivity Table 2 , 3
UT : AWSD1.5  6.17 Equipment Qualification
In the above part, there are approval priod etc...
I may prepare daily check sheets.

Next question OK?
I wolud like to know the following.
MT,UT : scanning overlap and scanning speed, Magnetizing Time.
I didn't find that description.
I only understood 100 percent inspection.
Please teach me.
Parent - - By g32141 (**) Date 09-15-2007 18:55
You need to obtain the codes that you are working to and the codes that they reference. That's all I can teach you.

Read them through and if you have questions keep asking.

Someone can help you eventually. There is only one dumb question and that is the one that you never ask.
Parent - - By kazu (*) Date 09-26-2007 08:54
Please teach me Equipment Qualification Procedures.
I don't understand "Decibel dB Accuracy Procedure".
From (6) to (7).
Increase the sound amplitude 6 dB, 80% screen height.(5)
Next, (7) Move the position U, 40% screen heigh?? (decrease??)

And FORM &#8550;-8, "a" dB Reading value is 6, 12, 18...
+6,+6+6....????? (addition??)
Parent - - By g32141 (**) Date 09-27-2007 21:00 Edited 09-27-2007 21:33
Send me the code in a PDF format and let me take a look at it. Without the code you are using in front of me I can't help you.

It sounds like you are trying to do a vertical linearity check.

I can't teach you anything but just point you into the right direction.
Parent - - By kazu (*) Date 09-29-2007 08:30
Sorry, I am hurrying up.
About Decibel dB Accuracy Procedure.
AWS D1.1/D1.1M:2002 and AWS D1.5M/D1.5:2002.
What does "dB Reading" mean?
Example of the use of form D-8 UT Unit Certification.
Add 6, 12, 18... dBs equal to "dB Reading"?
or 40 percent screen height dB + Add 6, 12, 18...?
Parent - By RANDER (***) Date 09-29-2007 22:13
Kazu,

This forum is not meant to be a replacement for technical training in the fundamentals/theory/practice of Ultrasonics. People are more than willing to help here but you must help yourself by getting some real training and education from a technical program or OTJ with a level III certified practioner. 
I apologize if I am making too great of an assumption here but you will find most answers to your questions with some proper study and training if you dont have it already. 

Respectfully,
Rob
Parent - By Joseph P. Kane (****) Date 09-29-2007 17:18
I was amused at this string at first. 

Now I am beginning to to get alarmed. 

Here is a person who does not have a clue, but is apparently eager to learn.  I wonder, if he will learn how to do just enough to complete an officious looking report, then go into actual practice - without being properly qualified?

I worry that this person will be performing UT and writing reports on actual production weldments without proper experience and qualification.

I THINK THAT ANSWERING THIS KAZU STRING MAY BE HARMFULL TO THE PUBLIC SAFETY!

Joe Kane
Parent - - By CWI555 (*****) Date 10-02-2007 02:40
Kazu,

I've tried to help you more than I probably should have. I've worked with several of your countrymen recently and have come to the conclusion that JSNDI trained personnel are ill prepared for AWS D1.1 work. I've worked with them extensively trying to enlighten them as to the ins and out of AWS DGS UT which took a considerable amount of time. These gentlemen were and are JSNDI LIII UT qualified. I've had the same difficulty with EN 473 personnel in which they just could not get away from the idea of needing a DAC and manual transfer correction instead of the A-B-'C"=D formula used by AWS. One of the things stated up front in D1.1 and D1.5 is that when the AWS code is specified for UT, the operator is required to demonstrate the ability to work to the rules of AWS UT.  Having said that, I am going to give you a suggestion. Based on the difficulties I've experienced with the JSNDI personnel, it would be advisable that you contract an ASNT level III who has extensive experience in AWS UT. ISO 9712, EN473, and JIS Z 2305 do not prepare you for DGS UT of the AWS nature. Even among the ASNT Level III's, not all are qualified to teach or perform AWS UT. Again I strongly advise contracting an ASNT Level III UT with extensive AWS UT experience to properly train you. Your original question was in regards to D1.5, which means your working on a bridge. Failure to properly execute the UT program can potentially cost lives in the event a fracture critical weld is improperly examined.

Regards,
Gerald
Parent - - By kazu (*) Date 12-19-2007 05:30
I would like to know the following word.
This word is "Leg". (Leg I, II, III)
What does the word "Leg" mean?
For example,
General Note:
"Where possible, all examinations shall be made from Face A and in Leg I, unless otherwise specified in this Table."
Please teach me.
Parent - By hogan (****) Date 12-19-2007 14:57
a leg is a measurement of the distance the sound travels from one side of the material to the other. it will be different for different angles.
Parent - - By CWI555 (*****) Date 12-19-2007 21:26
I have to say again, I strongly advise you contract an ANST Level III familar with D1.5 UT.
Parent - By hogan (****) Date 12-19-2007 21:46
woops i forgot. only read the one post
Up Topic Welding Industry / Inspection & Qualification / AWS D1.5 UT inspection

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