Tank foundation is the place where storage tanks are placed and requires firmness; It not only affects the appearance, but also causes uneven stress in the storage tank. The foundation of the storage tank belongs to the category of civil engineering and must comply with basic construction drawings and technical standards. Before installing the storage tank, the tank foundation must be inspected and can only be installed after passing the inspection.

Prefabricated assembly

For the manufacturing of large vertical storage tanks, it is generally necessary to prefabricate and assemble them in sections and segments, and then assemble them. This is very helpful for improving production efficiency. Firstly, the materials and accessories selected for the construction of the storage tank should be re inspected. The standard used is GB74003-88, which should meet the Level III standard to be qualified. Prefabricated assembly includes components and parts such as bottom plate, wall plate, floating roof and inner floating roof, fixed top plate, windproof ring, reinforcement ring, edge wrapped angle steel, etc.

Welding of storage tanks

For first-time use of steel, welding process evaluation is based on factors such as steel grade, plate thickness, welding method, and welding material., Conduct process evaluation according to current national standards and determine appropriate welding processes. The butt weld sample and the T-shaped fillet weld sample are used for welding process qualification. Perform tensile and transverse bending tests on butt weld specimens.

2. Welders who are required to engage in electrode arc welding, submerged arc welding, and gas electric vertical welding should be evaluated in accordance with GB50236-1998. Welders who pass the examination according to the "Assessment Rules for Welding Operators of Special Equipment" and obtain the qualification certificate of steel grade, group and specimen classification code issued by the quality and technical supervision department may engage in welding of tank parts without further examination.

3. Preparation before welding: To ensure welding quality, welding equipment should meet the requirements of tank welding construction. For tank wall butt welds with tensile strength b ≥ 430 megapascals and plate thickness ≥ 13 millimeters, low hydrogen welding rods should be used for welding. Before welding, the welding material should be dried and used according to the specifications in the product manual or Figure 1. The dried low hydrogen electrode should be stored in an insulated tube at 100 ℃~150 ℃ and can be removed as needed. It is worth mentioning that sealed flux cored wire and sealed box flux cored wire should no longer be dry in principle, and the flux cored wire should be cooled to room temperature and dried before use.

4. Clean the qualified steel plates for welding construction, prepare the groove according to the drawing requirements, and fix the positioning welding fixtures firmly. For ordinary carbon steel and low-alloy steel, the length of each weld seam should not be less than 50 millimeters. Low alloy steel with a yield strength greater than 390 megapascals should not be less than 80 millimeters. Before welding, the assembly quality should be checked, and sediment, rust, moisture, oil stains, and dirt on the groove surface and within a 20mm range on both sides should be removed, and dried separately. To ensure the quality of the beginning and end of the weld seam, the reverse arc method should be used at the groove at the beginning, and guide plates can be used if necessary. When terminating the arc extinguishing, the arc pit should be filled. The indirect ends of multi-layer welding should be arranged in a staggered manner. Note: Arc initiation and extinguishing should be on the groove or weld seam. The butt joint welded on both sides should be rooted before welding on the back. When using carbon arc gouging, the root should be repaired with a grinding wheel after cleaning. When s ≥ 390 megapascals, penetration inspection should be performed after root cleaning. Overlapping fillet welds with a thickness greater than 6mm should be welded at least twice.