Advanced Inspection and Acceptance Procedure for Steel Structure Galvanization in Transmission Projects

Dubai Electricity & Water Authority (DEWA) uses tubular monopoles and steel lattice towers for the transmission and distribution of 400kV and 132kV voltages for overhead lines. Transmission towers are an essential part of DEWA?s power grid construction work and plays a vital role in the power transmission process. Transmission towers are exposed to external environment and easily affected by environmental pollution. Due to rapid shifts in relative humidity and higher airborne salinity levels corrosion may easily occur. This affects the service life of the tower and its performance. In order to prevent corrosion, anti - corrosion treatment must be carried out in the process of manufacturing the tower. Galvanization of tower parts using hot dip process is carried out to protect the steel from corrosion. The tower parts used in DEWA power grid systems are galvanized in accordance with DEWA technical specification requirements. Hot dip galvanizing of tower parts ensures many years of zero maintenance there by lowering the life cycle costs. Galvanization process shall comply with requirements laid on international standards ASTM A123 and A153 and procedure to avoid material embrittlement as per ASTM143. Galvanized tower parts are tested to ensure DEWA OHL specification requirements as per the guidelines given in ISO1461. DEWA ensures strict quality control by scrutinizing tower fabricator?s manufacturing quality plan and by conducting quality assessment tests at tower fabrication factory before giving dispatch clearance to tower supplier for delivery of materials at site. Tower fabricator has to obtain DEWA approval for material suppliers of steel and bolt, nut accessories and the inspection test plan. The different stages involved in the galvanization process, Inspection procedure and acceptance criteria on galvanization of finished goods are addressed in this article.