PLUG-METRIC 9U7139 - Caterpillar

WELDING ELECTRODESProper preparation of the weld area must beconducted prior to any weld repair. Clean the area to be welded with agrinder. All paint, rust, oil, scale, slag, dirt, moisture, etc. must becompletely removed. Any dye penetrant must also be removed with the appropriatecleaner. After the crack is completely removed, prepared and cleaned itmay be weld repaired by one of the two following options:OPTION 1Preheat the weld groove and 3" in each directionfrom the weld centerline to 300 degrees F (150 degrees C). The maximuminterpass temperature should not exceed 450 degrees F (250 degrees C).Weld the prepared groove with either the SMAW or FCAW electrode as specifiedbelow.Electrode /CharacteristicsThe SMAW process may be used with E7018 (ANSI/AWSA5.1) welding electrode. The weld deposited by these electrodes will havethe following minimum mechanical properties:
TENSILE STRENGTH 480 MPa (70 KSI)
YIELD STRENGTH 400 MPa (58 KSI)
ELONGATION 22%
IMPACT TOUGHNESS 20 FT LBF @-20F (27J@-18C)Caution: These are low hydrogen electrodesand must be stored in an electrode oven at 120 degrees C (250 degrees F)when not in use. If the electrodes get damp, scrap or recondition to manufacturer'sspecifications.The following chart relates to the electrode diameterand approximate current settings for welding:
DIAMETER AMPS
3.2MM (0.125") 1/8" 70-140
4.0MM (0.156") 5/32" 110-180
4.8MM (0.166") 3/16" 190-270Use the direct current electrode positive (DCreverse polarity) polarity setting and remove the slag after every pass.The weld pass weave width shall not exceed two times the electrode diameter.OPTION 2As an alternative process the FCAW processmay be used with E71T-1 H8 (ANSI/AWS A5.20) welding electrode and the manufacturersspecified shielding gas (es). The weld deposited by these electrodes willhave the following mechanical properties:Caution: Only use flux-cored electrodes thathave been properly stored in moisture resistant packages that are undamagedor which have been placed in a drying oven maintained at 250 degrees F(120 degrees C).
TENSILE STRENGTH 480 MPa (70 KSI)
YIELD STRENGTH 400 MPa (58 KSI)
ELONGATION 22%
IMPACT TOUGHNESS 20 FT LBF @-20F (27J@-18C)Welding parameters will vary due to weld positionand manufacturer of the welding electrode. For 1.3mm (0.052 inch) diameterelectrode typical welding parameters should be:
WIRE FEED SPEED VOLTAGE APPOX. AMPERAGE
MIN 200 IMP 24 210
OPT 275 IMP 28 250
MAX 325 IPM 29 300Use the direct current electrode positive (DCreverse polarity) setting and remove the slag after every pass.POST WELD INSPECTIONUse dye penetrant or the magnetic particlemethod to inspect the weld repair after it is allowed to cool for 48-72hours. The weld shall be free from cracks, porosity, undercut, and incompletefusion. All weld quality shall conform to ANSI/AWS 14.3 or CaterpillarEngineering Specification 1E99.CRACK REPAIRThe sequence of operations for weld repairis as follows:1. Locate and mark understructure cracks bya through visual inspection.2. Completely remove cracks by grinding orcarbon arc gouging followed by grinding. Verify crack removal by additionalinspection using die penetrant.3. Preheat area to be repaired to 300 F (150C) not to exceed 450 F (250 C).4. Using one of the welding process optionsdescribed, and a balanced welding technique, complete the repairs.5. For Cold ambient temperatures prepare areafor thermal soak, slow cooling, allowing at least one hour to cool.6. Perform any profile grinding or dressingof welds.7. Conduct a post-repair visual inspectionand/or die penetrant inspection.