Low-hydrogen electrodes for shielded metal arc welding were developed to control the contamination of the weld and weld metal from hydrogen absorption during welding. The moisture content of the electrode covering is maintained within specification limits, usually less than 0.15% moisture. Low-hydrogen (EXX15 and EXX16) and low-hydrogen, iron powder (EXX 18, EXX24, and EXX28) electrodes were

designed and developed to contain the minimum amount of moisture in the coverings.

To maintain this low moisture level in the covering, the filler metal manufacturer furnishes these electrodes in hermetically sealed containers. When the sealed container is opened, electrodes not used immediately should be stored in a holding oven at 120°C (250°F).  Electrodes should not exceed the moisture limits prescribed by the appropriate specification. Electrodes which have been exposed to the atmosphere for time beyond that permitted by the specification, or have been exposed to moisture, should either be discarded or reconditioned by re-baking. If not specified, information on the appropriate time and temperature for reconditioning should be requested from the manufacturer. Wet electrodes should be discarded. See FILLER METAL and SHIELDED METAL ARC WELDING.

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