Welding Electrodes
Proper preparation of the weld area must be completed prior to any repair welds. Clean the weld area with a grinder. All paint, rust, oil, scale, slag, dirt, moisture, and so on, must be removed. Any dye penetrant must also be removed with the appropriate cleaner.
Option 1
Preheat the weld groove and 76.2 mm (3.0 inch) in each direction from the center of the weld to 150 °C (300 °F). The maximum interpass temperature should not exceed 250 °C (450 °F).
Characteristic
The SMAW process may be used with E7018 (ANSI/A5.1) welding electrode. The weld that is deposited by these electrodes will have the following minimum mechanical properties.
| Mechanical Properties of Welds from Low Hydrogen Electrodes That Are Classified as “E7018 (ANSI/AWS A5.1)” | |
|---|---|
| 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) |
Note: The low hydrogen electrodes must be stored in an electrode oven at 120 °C (250 °F). The electrodes must be reconditioned to the manufacturer’s specifications if the electrodes get damp.
The following table relates to the electrode diameter and approximate current settings for welding.
| 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.
Option 2
Preheat the weld groove and 76.2 mm (3.0 inch) in each direction from the center of the weld to 150 °C (300 °F). The maximum interpass temperature should not exceed 250 °C (450 °F).
As an alternative process, the FCAW process may be used with E71T-1 H8 (ANSI/AWS A5.20) welding electrode and the manufacturers specified shielding gas. The weld that is deposited by these electrodes will have the following mechanical properties.
| Mechanical Properties of Welds from Low Hydrogen Electrodes That Are Classified as “E71T-1 H8 (ANSI/AWS A5.20)” | |
|---|---|
| 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) |
| 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 width of the weld should not exceed two times the electrode diameter.
Note: Heat the repair weld to 150 °C (300 °F) for at least 30 minutes. Heat for 1 hour per 25 mm (1.0 inch) of the base material thickness. Cover the repair weld with a thermal blanket. The blanket will slow the cooling. The blanket will assist in the release of hydrogen.
Finish Weld Inspection
Use the dye penetrant or the magnetic particle inspection process in order to inspect the repair weld. The repair weld should be allowed to cool for 48 hours to 72 hours. The weld shall be free from cracks, porosity, undercut, and incomplete fusion. All weld quality shall conform to (ANSI/AWS 14.3).