Introduction
This Special Instruction provides the necessary information on all welding procedures.
Proper Cleaning for Inspection
Before you inspect the area, clean the area with an appropriate high-pressure washer. Be careful not to damage wires or other components. Use an appropriate de-greaser to remove any oil or grease from the frame assembly. A wire brush or a scraper to remove excessive dirt and grease may also be needed. Make sure that the substances that follow are removed from the area that will be inspected.
- Oil
- Grease
- Dirt
Preparing the Area for Welding
Clean the area that will be welded. Make sure that the substances that follow are removed from the area that will be welded.
- Oil
- Grease
- Paint
- Dirt
If the temperature of the base metal is below 0 °C (32 °F), heat the base metal to a temperature of at least 21 °C (70 °F). Maintain the temperature of the base metal at 21 °C (70 °F) during the welding process.
Note: Heat distortion of the base metal is possible when you weld. Avoid excessive heating of the base metal.
Attach the welding ground cable directly to the base metal. Protect machined surfaces from sparks. Protect the machined surfaces from the weld splatter.
Weld Specifications and Qualifications
Note: Personal breathing protection should be worn by the personnel that are welding. Personal breathing protection will prevent fumes from entering the lungs of the person that is welding. Use a 1U-8088 Type H Respirator for breathing protection.
Qualifications
Welders must be qualified for fillet welding and groove welding. The welders should be qualified in the use of the welding processes that follow: Shielded Metal Arc Welding (SMAW), Flux Cored Arc Welding (FCAW) and Gas Metal Arc Welding (GMAW). Refer to “American National Standards Institute (ANSI)/American Welding Society (AWS) Specification D1.1, or Specification D14.3” for information that regards the qualifications for the processes that follow: SMAW process, FCAW process and GMAW process. The welders must have used the process at some time within the last 6 months. The welders must complete the process of certification if the welders have not used the welding processes for 6 months.
Proper Welding Procedure on Machines and Engines with Electronic Controls
Proper precautions are necessary to prevent damage to electronic controls. When you weld on a machine with electronic controls, use the steps that follow:
- Turn off the engine. Put the key start switch in the OFF position.
- If the machine has a battery disconnect switch, open the switch. If the machine does not have a battery disconnect switch, disconnect the negative battery cable at the battery.
- Connect the ground cable for the welder directly to the actual machine component that will be welded. Attach the clamp for the ground cable as close as possible to the area that is being welded. The ground cable will reduce the chance of damage from welding current to the components that follow: bearings, hydraulic components and electrical components.Note: Do NOT use electrical components as a ground point for the welder. Do NOT use ground points for electronic components as a ground point for the welder.
- Protect the wiring harnesses from the weld splatter.
Specifications
Low Hydrogen Electrodes for the SMAW Process
The tables that follow list the mechanical properties of welds that are deposited by low hydrogen electrodes.
Mechanical Properties of Welds from Low Hydrogen Electrodes That Are Classified as “ANSI/AWS A5.5 E10018-D2” | |
---|---|
Tensile Strength | 690 MPa (100076 psi) |
Yield Strength | 600 MPa (87000 psi) |
Elongation | 16% |
Impact Toughness | 27 J @ -50 °C (20 ft lb @ -60 °F) |
Mechanical Properties of Welds from Low Hydrogen Electrodes That Are Classified as “ANSI/AWS A5.1 E7018” | |
---|---|
Tensile Strength | 480 MPa (69618 psi) |
Yield Strength | 400 MPa (58015 psi) |
Elongation | 22% |
Impact Toughness | 27 J @ -18 °C (20 ft lb @ -20 °F) |
Low hydrogen electrodes must be stored in an electrode oven at 120 °C (248 °F). If low hydrogen electrodes get damp, scrap the low hydrogen electrodes or recondition the low hydrogen electrodes to the specifications from the manufacturer.
The table that follows shows setting for the welding current for the electrode diameter.
Welding Current for Low Hydrogen Electrodes | |
---|---|
Diameter | Amperage Rating |
3.2 mm (0.125 inch) | 70-140 |
4.0 mm (0.157 inch) | 110-180 |
4.8 mm (0.189 inch) | 190-270 |
Use a polarity setting of DC reverse polarity. Remove the slag after each pass of the welding electrode. The width of the weld should not exceed two times the electrode diameter.
Flux Cored Welding Electrode for the FCAW Process
As an alternative process, use the Flux Cored Arc Welding (FCAW) with E71T-1 H8 (ANSI/A5.20) welding electrode and the manufacturer’s shielding gases that are specified for inside welding. The H8 implies that the electrode is designed to provide less than 8 ml/100 g of diffusible hydrogen in the weld deposit. The weld that is deposited by the flux cored welding electrode will have the following minimum mechanical properties:
The table that follows lists the mechanical properties of welds that are deposited by the flux cored welding electrode.
Mechanical Properties from Flux Cored Welding Electrode That Is Classified as “ANSI/AWS A5.20 E71T-1” (1) | |
---|---|
Tensile Strength | 480 MPa (69618 psi) |
Yield Strength | 400 MPa (58015 psi) |
Elongation | 22% |
Impact Toughness | 27 J @ -18 °C (20 ft lb @ -20 °F) |
( 1 ) | The properties that are listed are for three passes of the welding electrode. |
The table that follows shows setting for the welding current for the flux cored welding electrode that has a diameter of 1.3 mm (.051 inch).
Welding Current for Flux Cored Welding Electrode That Is Classified as “ANSI/AWS A5.20 E71T-1” | ||
---|---|---|
Wire Feed Rate | Voltage | Amperage |
Minimum 5080 mm (200 inch) Per Minute |
24 | 210 |
Optimum 6985 mm (275 inch) Per Minute |
28 | 250 |
Maximum 8255 mm (325 inch) Per Minute |
29 | 300 |
Note: The settings for the welding current can vary due to the position of the weld. Also, the settings for the welding current can vary with the manufacturer of the welding electrode.
Use a polarity setting of DC reverse polarity. Remove the slag after each pass of the welding electrode. The fast freezing characteristics of flux cored welding electrode increases the possibility of evolving gas that is trapped in the weld. Control the size of the weld in order to reduce the possibility of evolving gas that is trapped in the weld. The volume of the fillet weld should not exceed 8.0 mm (.315 inch).
Arc Welding Electrodes for the GMAW Process
The table that follows lists the mechanical properties of welds that are deposited by the GMAW Process.
Mechanical Properties of Welds from Arc Welding Electrodes That Are Classified as “ANSI/AWS A5.28 ER100S-2” | |
---|---|
Tensile Strength | 690 MPa (100076 psi) |
Yield Strength | 610 MPa (88473 psi) |
Elongation | 16% |
Impact Toughness | 68 J @ -51 °C (50 ft lb @ -60 °F) |
The welding parameters will vary with the position of the weld and with different electrode manufacturers.
Weld Inspection
The weld should not have any of the conditions that follow:
- Cracks
- Porosity
- Undercut
- Incomplete Fusion
In order to verify the quality of the weld, refer to”American National Standards Institute (ANSI)/American Welding Society (AWS) Specification D14.3″.
General Repair for Cracked Welds
- Remove any components that prevent access to the cracked weld.
- Clean the weld of the substances that follow: oil, grease and dirt.
- Use the dye penetrant to inspect the entire area for possible cracks.
- Protect machined surfaces from sparks and weld deposits.
- Use an air carbon arc torch or use a grinder in order to remove cracks. Use a grinder to remove cracks that extend through the castings. Remove at least 50.8 mm (2.0 inch) of material past each end of the crack. When the crack is removed, the bottom of the groove should have an angle of 90 degrees in order to ensure sufficient penetration. The side walls of the groove should extend upward at an angle of 45 degrees.
- Use the dye penetrant to inspect the gouged area in order to ensure that the crack has been removed. Be sure to clean the prepared groove before welding.
- Use Welding in order to repair the prepared groove by using passes that do not exceed two times the electrode diameter. If the alternate welding process is selected, the size of the weld pass should not exceed 7.88 mm (0.31 inch) by volume. Do not allow any slag inclusion when multiple pass welding is used.
- Clean the weld and inspect the weld. The weld must be free from the following: cracks, porosity, undercut and incomplete fusion. All quality of the weld must conform to ANSI/AWS standard 14.3.