Guidelines for the Installation, Inspection, Maintenance and Repair of Structural Supports for Highway Signs, Luminaries, and Traffic Signals
Appendix D Ultrasonic Anchor Inspection Procedure
Appendix D Ultrasonic Anchor Inspection Procedure
Fish Inspection and Testing LLC Ultrasonic Anchor Bolt Inspection Procedure
This procedure when specified shall be the method used to ultrasonically examine bolts to locate fatigue cracks perpendicular to bolt length.
ASME Section V
American Welding Society D1.1
Qualification and Certification of NDT Personnel
Control of Measuring and Test Equipment
The personnel implementing this procedure shall be certified in accordance with Fish Inspection and Testing LLC NDE Quality Assurance Manual "Qualification and Certification of NDT Personnel," as either Level II or III to evaluate results, or Level I to perform the operational portion of the examination and record data while under the direct supervision of a Level II or III.
Equipment and Material
Equipment and materials used to implement this procedure will be calibrated and certified in accordance with Fish Inspection and Testing LLC NDE Quality Assurance Manual "Control of Measuring and Testing Equipment." A copy of the equipment and material certifications wilt be available at the request of the client.
The ultrasonic instrument shall be a Pulse-Echo type unit equipped with an A scan presentation and capable of generating frequencies over the range of 1 MHz to 5 MHz. The instrument will also be equipped with a calibrated attenuator in one (1) or two (2) db steps with an accuracy over its range of ± 2db.
- Search units should be single element transducers.
- Transducers may be 1 MHz to 5 MHz in frequency.
- Search unit crystals may be 3/8 inch to 1/2 inch in diameter.
Calibration blocks shall be either International Institute of Welding (11W) Type I of Type II or Distance and Sensitivity Calibration Block (DSC) used in conjunction with calibration standards of Paragraph D. At the option of the client, specific calibration standards can be prepared at their discretion to verify adequacy of this procedure.
Calibration standards shall be made out of the same or similar material as the bolts being examined. The standard shall be made of material free of indications that may affect calibration. The optional standards should be of the same diameter and length and material type as the bolts being examined. The standards shall be machined with a 1/8 inch deep saw cut below the root of the threads. The saw cut shall be located at 2 inches, 4 inches, 6 inches, and 8 inches from the threaded end of the bolt. The saw cut shall be located perpendicular to the end of the bolt. The end of the bolt shall be flat and smooth as to not interfere with free movement of the search unit. The saw cuts shall be located in different quadrants so they do not mask the notch below.
Prerequisites, Precautions and Limitations
The surface of the test material shall be flat, smooth and in its final condition prior to the examination. This may require the use of hand grinders to facilitate search unit movement.
The same equipment used for calibration shall be the same as used for examination purposes. This includes the ultrasonic instrument, cables, search unit and couplant. Any change in this equipment requires recalibration.
This procedure may be used for 1/2 inch to 3-inch diameter bolts. The area of interest shall be the first ten inches. If the area past the first ten inches is to be examined, further evaluation should be performed before using this procedure with special attention to beam spread and mode conversion. This evaluation will be performed by Fish Inspection and Testing LLC level ultrasonic examiner and results approved by the client prior to any examinations.
The surface to be examined shall be smooth and tee of roughness or other conditions that would interfere with free movement of the search unit or impair the transmission of ultrasonic waves. The nut should be fully threaded past the end of the bolt so as not to interfere with search unit scanning area.
- Calibration shall include the complete ultrasonic examination system. Any changes in search units, shoes, couplant, cables, instruments, or recording devices will result in a calibration check. The initial calibration must take place on the IIW, DSC or optional calibration standards.
- The CRT screen shall be calibrated for a 10-inch screen range using the approved calibration blocks in Paragraph 1. Then place the search unit on the threaded end of the calibration standard. Locate the closest or 2-inch saw cut. Adjust the amplitude to 90 percent. Record the instrument setting on the examination sheet. Next, locate the 4-inch saw cut. Note the peak amplitude on the examination sheet. Also. mark the screen with an erasable marker. Do the same for the remaining two saw cuts. Next, connect the marks of the screen to create a Distance Amplitude Curve (DAC).
Straight Beam Examination of Bolts
- With CRT screen calibrated according to Paragraph B.2. Position the search unit on the bolt to be examined. The entire surface of the bolt shall be scanned at 12Db over reference.
- Accept/reject standards - any indication within 20 percent DAC at reference level, the indication shall be recorded. If any indications are found to exceed DAC at reference level, the bolt shall be considered reject and should be recorded on the examination sheet. If no indications are found, the bolt shall be considered acceptable.
- Anchor bolt length may be verified if plans showing anchor bolt details are available. Caution: If anchor bolts have a bent hook at ends, length measurement may not be possible.
- Calibrate the instrument for screen range required to analyze full bolt length using the AWS IIW block. Take measurements of the total bolt length and record it on, the examination sheet for each of the bolts.
System Calibration Check
- A system calibration check which verifies the instruments' sensitivity and sweep range calibration shall be performed at the start and finish of each examination or with any change of examination personnel or at least every 4 hours during the examination.
- System recalibration shall take place when one or more of the following occur.
- Any change of examination personnel.
- Any change of examination equipment cables, transducers or instruments.
- Any change of interruption in the power supply.
- When the operator doubts the validity of the calibration.
- All excess couplant shall be removed after completing examination.
- If original coating was removed for examination, examination area shall be recoated with a rust inhibitive coating approved by the client.
- if any point on fine DAC curve has decreased 20% of 2db of its amplitude, all data sheets since the last calibration will be marled void. A new calibration sheet shall be completed and all areas examined since the last calibration shall be re-examined.
- If any point on DAC curve increases 20% or 2 db of its amplitude, the same corrective action as Paragraph G.1 shall be taken.
- If any point on the DAC curve moves more than 10% of the horizontal sweep, all data taken since the list calibration shall be corrected.
Evaluation and Recording of Results
All defects or discontinuities revealed by the examination will be evaluated in accordance with Paragraph C2 and reported to the client.