Damages in weld joint of water elevated reservoir steel structures

Abstract

Water elevated reservoirs are commonly designed for drinking water storage in small communities. Usually they comprise prefabricated steel structures of elevated tanks, especially due to fast assembly of the component parts once parts of the structure just need to be connected. That one was the construction system used in small communities in the State of Tocantins, Brazil. However, weld joint failures have caused degradation and damage occurrence in the water elevated reservoir components welded by Shielded Metal Arc Welding (SMAW) process that uses a flux-coated electrode to form the weld. In this work, an investigation was carried out in order to analyze the existence of pathologies in the welded joints in the water elevated reservoir located in Tocantins. Following, the components were tested to tensile strength (NBR 6892-1: 2013) in plates equal to those used in water elevated reservoirs and with joints welded intentionally with the same identified pathology. The damages found by visual analysis were related to fast cooling, slag inclusions, high and low welding amperage and moist welding electrodes. Concerning the tensile strength test, joint welded with low welding amperage and joint welded with moist welding electrodes presented more damages, results that evidenced the importance of the quality control of the weld in this construction system.