PIN 1702187 - Caterpillar

Image1.1.3
Ultrasonic Thickness Inspection
Equipment ? Cat 168-7720 Ultrasonic Wear Indicator III Group (168-7721 UT Wear Indicator, 168-7722 UT Probe, and 9U-7981 UT Couplant)
Equipment Setup ? Ensure the UT probe is connected and the indicator is on by pressing the ON/OFF Key. The measured value needs to be displayed in MM to change press the MM/INCH key until MM is displayed. To calibrate the indicator apply a small amount of UT couplant on the face of the UT probe and place the probe on the Calibration Disk(6.3mm), then press the Probe Cal key, (Probe) will be displayed, continue to press the transducer to the calibration disk until the measured value display shows 6.3mm. If the thickness shown is not 6.3mm repeat the calibration process. Reference Image 1.2.1.
Image1.2.1
Inspection Procedure ? Couplant should be applied to the specific highlighted areas in Image 1.3.1. The areas should be scanned to get complete coverage of the entire area highlighted. Care should be taken to ensure proper thickness readings are observed. The measured value on the indicator will blink while scanning and denotes the indicator is getting readings. Not all areas will have parallel back walls and obtaining readings may be difficult in some areas. Reference Image 1.3.1 Section A-A and B-B for thickness profiles through the cross section.
Marking Areas for Repair ? If a thin wall condition is found, below minimum wall thickness, it is required to record the area and minimum thickness on the parts surface. The thin area should be mapped by placing the UT probe in the thin area and scanning outward until the thickness is found above nominal. At this point a mark should be made at the center of the transducer, repeat this action to provide an outline of the thin area on the part. The minimum thickness shall be recorded on the parts surface to help establish the thickness of weld repair. A picture of the thin area under the minimum thickness should be saved for future reference and documentation by truck serial number.
Inspection after Repair ? After the weld repair is finished per Image 1.8.1 the area of repair shall be inspected to ensure adequate buildup of weld material thickness equal to or greater than the nominal thickness requirements in Image 1.3.1. Follow initial inspection procedure for repair inspection.
Image1.3.1
If the area does not meet the ?minimum? wall thickness as depicted, then build up the appropriate area by welding to the "nominal" wall thickness shown in Image 1.3.1.
If a crack exists in one of the areas, repair the crack and then restore the area to the "nominal" wall thickness as depicted.
For those situations requiring build up:
Image 1.4.1 depicts an approximation of the cross section for a thin wall casting condition that is inspected to be below the ?minimum? wall thickness and requires the addition of weld metal. X represents the amount of material below the "nominal" wall thickness. X also represents the amount of material that will be needed to be added by welding to bring that area