Technical Construction of Vessels-Welding, Fabrication

• Orbital weld and straight bead have to be, as far as technically possible, counterwelded.
• Nozzle and flange weldings > DN80 have to be counter-welded.
• All nozzle ends have to be smoothed off at the inside edge r = 3 mm.
• Cold coiled dished heads and parts from Mat. 1.4539 have to be solution annealed.
• When using TIG welding backs of the weld have to be rinsed with argon or forming gas during the welding process.
• Bracing sheets have to be smoothed off with 4-times-plate-thickness minimum. All drill holes have to be closed leak-proof before caustic treatment.
• Working residues such as welding cinders, welding chips, temper colour, or caustic rests have to be removed. Vessels that show scratches, drag lines etc. at dished heads, cone bottom and sheets are not quality standard of BDI – BioDiesel International AG and are thus not handed over. The producer has to take care that dished heads, rolled up sheets and cones are delivered resp. constructed in an appropriate manner so that scratches, drag lines on the vessels etc. are avoided.

• The welding filler used have to be indicated.
• At austenitic apparatuses medium sided no constructional fissures are permissible.
• During welding in winter it has to be paid attention on processing temperature of steel (preheat!)
• Storage tank pan may only be cleared of snow and ice with conventional instruments (bucket grit), in no case use salt
• Each engaged welder have to have a updated welding-certificate on site
• After errection the tank farm foundation has to be cleaned – permanent discolouring caused by dust or paint are not acceptable

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