Ultrasonics aws

04/13/231

Ultrasonic Testing

Weld Inspection using AWS D1.1

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Introduction

This presentation will help students perform testing using the American Welding Society Structural Steel D1.1-2000 code and procedure.

It is important to remember that this is a general training program and the procedure should be referenced for specific information.

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What you will learn

Completing Form D-11 Determine the proper transducer(s) needed for

testing a weld. Calibration using an IIW, rumpus, and DSC

block. Scanning for discontinuities. Calculate size and location of a discontinuity. Accept/Reject evaluation of a discontinuity.

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Form D-11

Weld Identification Material Thickness Type of Weld Joint Welding Process Quality Requirements Section Number Year of AWS D1.1 Code used. Testing Date Inspected By

Some basic information should be completed on form D-11 prior to the inspection. This information includes the following:

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Step 1 – Specimen Measurement Measure the part thickness. From this thickness you will need to

calculate the skip distance. The skip distance is the area where you will scan the part with the proper angle transducer. Mark the end of the skip distance from the edge of the heat affected zone (HAZ). The area in red will be used to identify the heat affected zone.

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Step 2 – Inspection Layout The skip distance will equal the surface distance of the two legs.

You will need to know the distance of this area in order to perform a lamination scan followed by an angle beam examination

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Inspection Layout Identifying the skip distance from the edge of the

HAZ will ensure complete coverage of the weld when performing an angle beam examination.

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Step 3 – Lamination Scan A lamination scan will be performed in the area

where the angle beam inspection will take place. This scan is performed with a straight beam transducer.

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Lamination Scan Perform a lamination scan from face “A”. You will need

to see at least two plate thicknesses on the display. The first backwall reflection shall be 50 to 75% full screen height.

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Lamination Scan If any area of the base metal shows a total loss of

backwall reflection, or if an indication is equal or greater to the backwall reflection, the size and location and depth will be reported.

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Lamination Scan Move the transducer in all directions until the

amplitude of the signal is reduced by 50%. Mark the center of the transducer.

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Lamination Scan The area can be measured and included in the report. This

area should be avoided when performing an angle beam examination or an alternate scanning procedure shall be used.

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Lamination Scan Note the location and size of the lamination on report

form D-11 or write an additional report with a drawing showing its location.

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Step 4 – Transducer Angle Table 6.6 will list the transducer angles needed to test the weld.

For material 0.60” the transducer angle used will be 70 degrees and will be tested from face “A”. On Form D-11 record the transducer angle and face which you will be testing from. The face is determined from Table 6.6

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Step 5 – Screen Range Calculate the full V-path. This is determined by the

material thickness and transducer angle. Choose the appropriate screen range in order to see a minimum sound path of two legs.

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Step 6 – Screen Range Calculate the full V-path. This is determined by the

material thickness and transducer angle. Choose the appropriate screen range in order to see a minimum sound path of two legs.

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Transducer Verify the transducer is coupled to the wedge

and there are no air pockets between the two.

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Calibration - IIW Block All measurements are taken from where the signal

breaks the baseline of the ultrasonic screen.

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Screen Range – IIW Block Adjust the ultrasonic machine to obtain the proper

screen range. With an IIW type II block shown, the backwall reflections will be located at 2” and 4”.

Position of the signals with a 10” screen range.

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Screen Range – IIW Block The position of the 2” and 4” reflections when using a

5” screen range.

Position of the signals with a 5” screen range.

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Screen Range – DSC Block The distance and sensitivity calibration block (DSC) can be

used for calibration. With the transducer placed in the position shown, the reflections will take place at 1”, 5”, 9”, etc.

Position of the signals with a 10” screen range.

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Screen Range – DSC Block With the transducer placed in the position shown, the

reflections will take place at 1”, 5”, 9”, etc.

Position of the signals with a 5.0” screen range.

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Screen Range – DSC Block With the transducer placed in the position shown, the

reflections will take place at 3”, 7”, 11”, etc.

Position of the signals with a 10” screen range.

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Screen Range – DSC Block With the transducer placed in the position shown, the

reflections will take place at 3”, 7”, 11”, etc.

Position of the signals with a 15” screen range.

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Screen Range – Rumpus Block The miniature calibration block or rumpus block can also be

used for calibration. With the transducer placed in the position shown, the reflections will take place at 1”, 4”, 7”, 10” etc.

Position of the signals with a 5” screen range.

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Screen Range – Rumpus Block With the transducer placed in the position shown, the

reflections will take place at 1”, 4”, 7”, 10” etc.

Position of the signals with a 10” screen range.

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Screen Range – Rumpus Block With the transducer placed in the position shown, the

reflections will take place at 2”, 5”, 8”, etc.

Position of the signals with a 5” screen range.

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Screen Range – Rumpus Block With the transducer placed in the position shown, the

reflections will take place at 2”, 5”, 8”, etc.

Position of the signals with a 10” screen range.

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Step 7 – Transducer Exit Point Determine the exit point of the transducer. Peak the signal on the

ultrasonic machine and verify that the index point on the plastic wedge matches the calibration block. You may use tape and a pen to mark the exit point. This will allow for easier measurements when measuring the surface distance.

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Exit Point – IIW Block The exit point and screen range can be performed at the same

time. Slide the transducer back and forth until the signal is maximized. The pictures below shows the location of the transducer when verifying the exit point using an IIW type II block.

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Exit Point – DSC Block The exit point and screen range can be performed at the same

time. Slide the transducer back and forth until the signal is maximized. The pictures below shows the location of the transducer when verifying the exit point.

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Exit Point – Rumpus Block The exit point and screen range can be performed at the same

time. Slide the transducer back and forth until the signal is maximized. The picture below shows the location of the transducer when verifying the exit point.

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Step 8 – Transducer Angle The angle of the transducer will need to be verified. It

shall be within plus or minus 2 degrees of the required angle.

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Angle – IIW Block Slide the transducer back and forth until the signal is

maximized. The picture below shows the location of the transducer when verifying the transducer angle.

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Angle – DSC Block Slide the transducer back and forth until the signal is

maximized. The picture below shows the location of the transducer when verifying the transducer angle.

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Angle – Rumpus Block Slide the transducer back and forth until the signal is

maximized. The picture below shows the location of the transducer when verifying the transducer angle.

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Step 9 – Transducer Resolution The resolution shall be checked with the instrument controls set at normal

test settings and the indications from the holes brought to midscreen height. Resolution shall be sufficient to identify the peaks of the three holes.

Position of the signals with a 5” screen range.

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Step 10 – Reference Level

The amplitude of a known size reflector will be adjusted from 50-75% full screen height. The dB will be recorded as the reference level on form D-11.

IIW blockDSC block

Rumpus block

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Reference Level – IIW Block The transducer shall be placed in the position shown and the signal

amplitude from the hole will be maximized. Adjust the dB in order to obtain a signal from 50 to 75% full screen height. This will be used as the reference level “b” on form D-11.

Position of the signals with a 10” screen range.

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Reference Level – DSC Block The transducer shall be placed in the position shown and the

signal amplitude from the notch will be maximized. Adjust the dB in order to obtain a signal from 50 to 75% full screen height. This will be used as the reference level “b” on form D-11.

Position of the signals with a 10” screen range.

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Reference Level – Rumpus Block The transducer shall be placed in the position shown and the

signal amplitude from the hole will be maximized. Adjust the dB in order to obtain a signal from 50 to 75% full screen height. This will be used as the reference level “b” on form D-11.

Position of the signals with a 5” screen range.

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Step 11 – Reference Level In this example the reference level “b” would be

recorded as 42 dB. The reference screen height used is 60% FSH.

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Step 12 – Scanning Level Scanning level is based on sound path distance and not

material thickness. If table 6.2 (Statically loaded nontubular connections) are tested, the following scanning levels will be used.

Above ZeroSound Path (in) Reference, dB0.0” to 2.5” 14>2.5” to 5” 19>5” to 10” 29>10” to 15” 39

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Scanning Level If table 6.3 (Cyclically loaded nontubular connections) are

tested, the following scanning levels will be used.

Above ZeroSound Path (in) Reference, dB0.0” to 2.5” 20>2.5” to 5” 25>5” to 10” 35>10” to 15” 45

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Scanning Level This shows the screen presentation when using a

scanning level 14 dB above the reference level.

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Step 13 – Initial Information Scan

Perform an initial information scan marking the location of any suspected discontinuities.

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Weld Configuration You can draw a diagram of the weld on the ultrasonic screen

with a water based marker or grease pencil. The line is drawn at the end of the 1st, 2nd, and 3rd leg. This may help you visualize the location of the discontinuity in the weld.

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Step 14 – Surface Distance Calculate the surface distance in order to determine if

the signal is located in the weld.

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Step 15 – Discontinuity Depth Calculate the depth in order to determine if the signal

is located in the weld.

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Step 16 – Sound Path Move the transducer in all directions in order to peak

the signal from the discontinuity. Record the “Sound Path” on Form D-11.

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Step 17 – Sound Path Record the “Leg” on Form D-11.

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Step 18 – Indication Level Increase or decrease the dB until the screen height from the

discontinuity is equal to the reference level. Record the dB under indication level (column b).

dB reference level - 60% FSH.

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Step 19 – Attenuation Factor Subtract one inch from the sound path distance and multiply the

remainder by two. This number will be rounded to the nearest whole number. If the number is less than 0.5 dB it will be lowered to the nearest whole number. If the number is 0.5 or greater, it will be increased to the nearest whole number.

In this example, the sound path is 1.9”

1.9” – 1 = 0.90.9 x 2 = 1.8

Rounded to the nearest whole number - 2

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Attenuation Factor On Form D-11, fill out the attenuation factor. This is

located under “Decibels- Attenuation Factor.

In this example, the sound path is 1.0”

1.0 – 1 = 0.00.0 x 2 = 0.0

If the attenuation factor is less than 0.5, the attenuation factor will be zero.

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Step 20 – Indication Rating

The indication rating is calculated by taking the “Indication level” minus “Reference level” minus “Attenuation factor”. A-B-C=D

The answer “D” is your indication rating and can be positive or negative. Write this number in column “D” under “Decibels”, Indication Rating”

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Step 21 – Discontinuity Length

Maximize the signal amplitude from the discontinuity.

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Step 22 – Discontinuity Length Slide the transducer parallel with the weld until the

signal amplitude has reduced by 50%. Mark the location next to the weld aligned with the center of the transducer. Perform this procedure in both directions.

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Discontinuity LengthRecord the length on Form D-11.

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Step 23 – Discontinuity Class From Table 6.2 or 6.3, determine the Discontinuity

Severity Class. This is based on the Indication Rating and Length.

Class A (large discontinuity)Any indication in this category shall be rejected regardless of length

Class B (medium discontinuity)Any indication in this category having a length greater than ¾” shall be rejected.

Class C (small discontinuity)Any indication in this category having a length greater than 2” shall be rejected.

Class D (minor discontinuity)Any indication in this category shall be accepted regardless of length or location in the weld.

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Step 24 – Discontinuity Evaluation

On Form D-11 under “Discontinuity Evaluation” list the class of the discontinuity.

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Step 25 – Accept/Reject On Form D-11 under “Remarks” accept or reject the

discontinuity.

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Step 26 – Distance from “Y” One side of the plate or weld can be identified with a “Y”

location point. From the edge of the weld measure to the beginning of the discontinuity. Record “Distance from “Y” on Form D-11.

Distance from “Y” = 1.0” Distance from “Y” = 0.3”

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Step 27 – Distance from “X” From the center of the weld (marked in black), if the

discontinuity is located opposite the “Y” location mark, it will be measured as a positive number. This will be recorded under “Distance from X” on Form D-11.

Distance from X = 0.2”

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Step 28 – Distance from “X” From the center of the weld (marked in black), if the

discontinuity is located on the same side as the “Y” location mark, it will be measured as a negative number. This will be recorded under “Distance from X” on Form D-11.

Distance from X = -0.2”

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Step 29 – Scanning Level Return to the scanning level and locate the next

discontinuity for evaluation.