The works were carried out at the industrial facilities of Hellenic Petroleum SA, in Aspropyrgos, Attica and included local repairs at the welds of the shell plates of the spherical tank, repairs at the nozzle weldings and nozzle replacement.
More analytically:
a. Data of spherical tank Ρ-8852
Diameter: 14.6m, thickness of shell plates: 40 ÷ 60mm, material:
high tolerance steel ASTM A738
b. Works – methodology
Repair of 133 points of peripheral seams of the shell of the spherical tank and 4 nozzles with total seam length of 78m and replacement of 2 nozzles. Repair depth up to 54mm.
The repair works were carried out according to the following procedure:
§ Grinding of peripheral welding at the points shown during the Hellenic Petroleum inspection up to the depth of locating the internal errors and their eradication, confirmation of error eradication via controls by the Hellenic Petroleum SA inspection team
§ Local preheating at the repair points at temperatures of 150οC ÷ 315oC
§ Gradual welding at the repair points with intermediate magnetic controls and final ultrasound controls following the end of each welding
§ PWHT of all parts of peripheral seams and nozzles at the intervention-repair points
§ Surface final arrangement of peripheral seams, shell and nozzles
§ Cleaning, restoration and delivery of the spherical tank to Hellenic Petroleum SA
The works were carried out on a 24-hour basis without interruption.
The quality control was carried out by the Hellenic Petroleum SA inspection team.
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