18 Storing and Re-Drying Submerged Arc Fluxes Unionmelt bags are designed to reduce the amount of moisture intrusion, when they are completely closed. They are provided with layers of paper, as well as a film of plastic to help retard moisture penetration. However, when the bags are opened or if they become punctured, they should be kept in a closed container in order to ensure that the products remain low in moisture. If the flux becomes exposed to humidity, it can be re-dried. Re-drying flux can often restore it to its original, as-manufactured condition. In the case of fused submerged arc fluxes, a re-drying temperature of a minimum of 300°F (149°C) is recommended to assure the moisture is reduced to its original levels. For bonded fluxes, a minimum of 500°F. (260°C) is recommended. For bonded flux, it is important not to exceed 1000°F (538°C), or the welding characteristics of the flux may suffer. When re-drying the flux, it is important that the complete mass be brought up to the temperature designed. If the flux is held in large containers, this can take a very long time - perhaps over 24 hours. In thin layers, reduction in moisture can be accomplished in as little as one hour, for example, in layers one or two inches thick. The re-drying temperature and time, therefore, are dependent on the amount of moisture contamination and the thickness of the flux bed being dried. Flux Handling Condition* Holding Baking Type (Opened Bags) (Reconditioning) Fused 250°F (121°C) Min. 300°F (149°C) Bonded 250°F (121°C) Min. 500°F (260°C) Max.1000°F (538°C) * The actual baking time and temperatures are a function of the amount of moisture.
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