© COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON IV electrodes are immediately packaged in hermetically sealed metal containers following the high temperature bake. 4.3.1 Storage and Reconditioning - All low hydrogen electrodes will absorb some moisture from the air after the electrode container is opened.  Therefore, those electrodes that are not intended for use within a given period of time must be stored in a vented oven and maintained at a constant temperature. Various structural and military codes allow only specified times of exposure. These may be anywhere from 30 minutes to 8 hours depending on the electrode alloy, the relative humidity in the work area, and the critical nature of the application.  If the low hydrogen elec- trodes are exposed to the atmosphere beyond these time limits, they must be scrapped or reconditioned by rebaking in a vented oven for a specified time at a specific temperature. The recommended storage and rebake temperatures for Atom Arc low hydrogen electrodes are follows: STORAGE RECONDITIONED 225-300°F 1 hr. @700°F 4.3.2 Moisture Resistant Coating - Moisture absorption is of special concern to end- users such as shipbuilders and oil rig fabricators who are situated in areas of the world that have a high level of relative humidity.  As the temperature and relative humidity increase, the chance of absorbing moisture in the low hydrogen coating is greatly increased.  To combat this possibility, major electrode manufacturers have in recent years developed low hydrogen electrodes with moisture resistant coatings.  These coatings low the rate of moisture absorp- tion in electrodes that have been exposed to the air for extended periods, thus adding an extra degree of reliability to low hydrogen electrodes. The following graphs (figure 3) give an idea of the effectiveness of a moisture resistant coating.  The tests were conducted on Atom Arc 7018 electrodes.  The method of moisture testing chosen by ESAB is that described in Section 25 of the AWS A5.5-96 Specifi- cation.  This method was chosen because it satisfies the AWS specifications and is sensitive only to water, making it one of the most accurate and reliable methods of moisture determina- tion currently in use. The AWS structural code and military specifications allow a maximum of 0.40% and 0.20% moisture content, respectively, for E70XX low hydrogen electrodes.  As shown on the preceding graphs, the Atom Arc 7018 electrode satisfied this low moisture requirement for exposure times beyond those normally allowed in field use.

Lesson 1
The Basics of Arc Welding
Lesson 2
Common Electric
Arc Welding Processes
Lesson 3
Covered Electrodes for Welding
Mild Steels
Lesson 4
Covered Electrodes for Welding Low Alloy Steels
Lesson 5
Welding Filler Metals for Stainless Steels
Lesson 6
Carbon & Low Alloy
Steel Filler Metals -
Lesson 7
Flux Cored Arc Electrodes Carbon Low Alloy Steels
Lesson 8
Hardsurfacing Electrodes
Lesson 9
Estimating & Comparing Weld Metal Costs
Lesson 10
Reliability of Welding Filler Metals
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