Tank foundation tank foundation is the place the tank is placed, which is required to be firm; it only affects the appearance, but also causes uneven tank stress. Tank foundation belongs to the category of civil engineering, which must conform to the basic construction drawings technical standards. The tank foundation must be inspected before the installation of the tank, the tank can be installed only after the inspection is qualified.

　　Prefabrication assembly

　　For the manufacturing of large vertical storage tank, it is generally prefabricated combined by sections, then general assembly, which is very helpful to improve the production efficiency. First, the materials accessories selected for the construction of storage tank shall be retested, the standard: gb74003-88 shall meet the class III standard. Prefabrication assembly include: base plate, wall plate, floating roof internal floating roof, fixed top plate, wind resistant ring, reinforcing ring, edge angle steel other components parts.

　　Welding of storage tank

　　1. The welding procedure qualification is based on the steel grade, plate thickness, welding method, welding material, etc. for the steel used for the first time. According to the current national standards for process evaluation, determine the appropriate welding process. Butt weld specimens t-fillet weld specimens are used for welding procedure qualification. Tensile test transverse bending test shall be conducted for butt weld specimen.

　　2. Welders are required to be general welders engaged in electrode arc welding, submerged arc welding gas electric vertical welding, shall be qualified in accordance with gb50236-1998. Welders who pass the examination in accordance with the detailed rules for the examination of welding operators of special equipment obtain the qualification certificate of steel type, group test piece classification code issued by the quality technical supervision department may be engaged in the welding of tank parts without further examination.

　　3. Preparation before welding to ensure the welding quality, the welding equipment shall meet the requirements of tank welding construction. For butt weld of tank wall with tensile strength B ≥ 430mpa plate thickness ≥ 13mm, low hydrogen electrode shall be used for welding. Before welding, the welding materials shall be dried used according to the product manual figure 1. The dry low hydrogen electrode shall be stored in a heat preservation tube of 100 ℃ ~ 150 ℃ can be taken out as required. It is worth mentioning that in principle, the sealed flux cored wire the sealed box flux cored wire are no longer dry, the flux cored wire shall be cooled to room temperature for drying before use.

　　4. The qualified steel plate shall be cleaned for welding construction, the groove shall be made according to the requirements of the drawings. The positioning welding fixture must be fixed firmly. For ordinary carbon steel low alloy steel, the length of each weld joint shall be less than 50 mm. Low alloy steel with yield strength greater than 390 MPa shall be less than 80 mm. Before welding, the assembly quality shall be checked, the deposit, rust, moisture, oil stain dirt on the groove surface within 20 mm on both sides shall be removed dried separately. In order to ensure the quality of the beginning end of the weld, the back arc method shall be adopted at the groove of the beginning guide plate can be used if necessary. When the arc extinguishing is terminated, the arc pit shall be filled. The indirect ends of the layers shall be staggered. Note: arc striking extinguishing shall be on the groove weld. Butt joints welded on both sides shall have root before back welding. When carbon arc gouging is used, the root shall be repaired with grinding wheel after cleaning the root. When s ≥ 390 MPa, penetrant inspection shall be carried out after root cleaning. Lap fillet welds with plate thickness greater than 6mm shall be welded at least twice.