The storage tank is a container used to store refined chemical substances such as acids, bases, alcohols, gases, and liquids. It can be manufactured and installed on-site, with specific construction plans.

1.Tank manufacturer productionInstallation construction plan

The storage tank is a storage container used to store refined chemical substances such as acids, alkalis, alcohols, gases, and liquids. It can be manufactured and installed on-site, and the specific construction plan is as follows:

1. Construction preparation

       (1) The construction site should be arranged according to requirements, with a flat area, and smooth access to water, electricity, and roads; the civil foundation construction must be completed, and the foundation must pass the handover inspection and meet the construction conditions; all types of construction personnel must be fully equipped, and special equipment operators must have the corresponding qualifications; all construction tools must be in place, and the storage areas for materials, semi-finished products, finished products, and waste must be clearly defined; safety protection measures must be implemented.

       (2) In terms of construction technical preparation, it is required to carefully read all construction technical documents, organize engineering technical personnel to review the drawings before construction, familiarize themselves with the drawings, design data, and relevant documents, and conduct a construction drawing review. Based on the requirements of the drawings and the site conditions, a feasible construction technical plan should be prepared and approved by the relevant supervisory departments. Before construction, the non-standard manufacturing technical personnel of the project department should provide technical and safety briefings to all construction personnel.

       (3) Foundation acceptance: Before the installation of the storage tank, the foundation construction records and acceptance data must be checked according to the civil foundation design documents, and the surface dimensions of the foundation must be rechecked according to the following regulations. Installation can only proceed after passing.

       (4) Material acceptance: The steel plates, profiles, and accessories used for the storage tank must meet design requirements and have quality certificates. The quality certificates should indicate the steel grade, specifications, chemical composition, mechanical properties, supply status, and material standards. The mechanical performance parameters must comply with current national or industry standards and meet the requirements of the design drawings.

2. Prefabrication of the storage tank

       (1) Prefabrication of the bottom plate: The bottom plate should be made according to the construction drawings, with the layout diameter of the tank bottom enlarged by 0.1% to 0.15% of the design diameter; the minimum size of the edge plate along the radius direction of the tank bottom should not be less than 700mm; the width of the middle plate should not be less than 1000mm; the length should not be less than 2000mm; the minimum straight edge size of the irregular middle plate connected to the edge plate should not be less than 700mm; the length of the edge plate extending outside the wall plate should not be less than 50mm; the distance between any adjacent welds on the bottom plate should not be less than 300mm.

       (2) Prefabrication of the wall plate: Similarly, prefabrication should be carried out according to the construction drawings. The surface of the steel plate after rolling should be flat and smooth, and the depth of any indentation should not exceed half of the allowable thickness tolerance of the steel plate, while the thickness of the steel plate at the indentation should not be less than the minimum thickness of the steel plate; all prefabricated parts should be clearly marked with a marker or paint upon completion of prefabrication. The wall plates should be placed horizontally on the ground after rolling.

       (3) Prefabrication of the fixed top plate: A layout drawing should be made before prefabricating the fixed top plate, paying attention to the splicing of individual top plates, which should be butt-welded and fully penetrated, with adjacent welds staggered and spaced at least 200mm apart.

       (4) Prefabrication of constructed components: After processing the edge angle steel, reinforcing rings, and other curved components, check their gaps with a curved template, which should not exceed 2mm, and their warpage should not exceed 0.1% of the component length, and should not exceed 6mm. Components formed by hot bending should not show signs of burning.

       (5) Production of expansion rings: After processing the expansion rings, check their gaps with a curved template, which should not exceed 1.5mm, and their warpage should not exceed 0.1% of the component length, and should not exceed 6mm.

3. Lifting method for the storage tank

       The construction of the storage tank is entirely carried out using the inverted installation method with a hoist, specifically the 'side column inverted method'. Four lifting columns are evenly set along the inner circumference of the tank wall (i.e., at 0°, 90°, 180°, and 270°), using Φ159x8mm steel pipes for the lifting columns, which should be 1000mm taller than the maximum lifting height. A counteracting brace is set on the side opposite the wall plate, and a 5-ton hand hoist is used for lifting.

During the lifting process, the following points must be observed:

       (1) The lifting columns must be installed according to the required dimensions, ensuring that the distances between the lifting points on the tank wall and the vertical columns are equal.

       (2) Before lifting, a height line can be marked on the lifting columns; during lifting, everything must be directed by the hoisting operator, with all lifting points rising synchronously, and the lifting height and speed must be consistent.

4. Assembly and installation of the storage tank

       (1) Before assembling the storage tank, the mud, sand, rust, water, and oil stains on the groove and lap joints of the components should be cleaned thoroughly.

       (2) Harmful defects such as scratches deeper than 0.5mm, arc damage, and welding scars should be ground smooth. The thickness of the steel plate after grinding and repairing should be greater than or equal to the nominal thickness of the steel plate minus the negative deviation; if the defect depth or grinding depth exceeds 1mm, it should be repaired by welding and ground smooth; the number of repairs at the same location should not exceed 2 times, and if it exceeds 2 times, it must be approved by the technical person in charge of the project department.

       (3) The edge plate of the tank bottom is a butt joint with a backing plate, and the butt welds should be fully penetrated, with a flat surface. The backing plate should be tightly fitted with the two bottom plates being joined, and the gap should not exceed 1mm. The gap at the butt joint of the tank bottom edge plate should meet the specified requirements.

       (4) The joints between middle plates and between middle plates and edge plates should use lap joints, and the lap length and welding should meet the requirements of the design drawings. Before laying the tank bottom plate, anti-corrosion treatment should be carried out according to the design drawings, with anti-corrosion paint applied to the underside of the tank bottom, leaving a 50mm margin unpainted at the edges of each bottom plate. After welding the tank bottom, the depth of any local deformation should not exceed 2% of the deformation length. When laying the bottom plate, the center positions at 0°, 90°, 180°, and 270° should be established first. The middle plates should be laid first, followed by the edge plates, with the sequence for laying the middle plates being: first laying the center strip of the middle plate, then laying the side strips on both sides of the center strip until the entire middle plate is laid.

       (5) Before assembling the tank wall, the prefabricated wall panels should be re-inspected and can only be assembled if they pass. The allowable deviation in the horizontal level of the upper edges of two adjacent wall panels should not exceed 2mm. The allowable deviation in the horizontal level between any two points on the entire circumference should not exceed 2mm; the allowable deviation in the vertical alignment of the wall panels should not exceed 2mm; the longitudinal welds of the wall panels in each ring should be staggered in the same direction, with a spacing of 1/3 of the panel length, and not less than 500mm; the distance between the longitudinal welds of the bottom ring wall panels and the welds at the edge of the tank bottom should not be less than 300mm; the distance between the outer edge of the pipe connection or reinforcement plate and the longitudinal weld of the tank wall should be greater than 150mm.

       (6) During the assembly of the wall panels, the inner surfaces should be flush, and the offset should meet the following requirements: the offset of the longitudinal welds should not exceed 1.5mm; the offset of the circumferential welds should not exceed 1.5mm. After assembly and welding, the local concave-convex deformation of the tank wall should be smooth, with no sudden fluctuations, and the local concave-convex deformation should be ≤15mm.

       (7) After the lifting tools and steel pads for inverted construction are ready, assembly should begin according to the wall panel layout diagram. First, assemble the topmost ring of wall panels, install the expansion ring at the bottom edge of the wall panels, and tighten the connection of the expansion ring with tension rods and bolts. Check whether the gap between the tank wall panels and the arc template meets technical requirements. Once all technical items are qualified, start welding the vertical seams of this ring panel (welding is not allowed within 100mm at the lower end). After all the top wall panels are welded, install and assemble the edge angle steel.

       (8) The installation of the top plate should be carried out after a single top plate is rolled into an arc shape and passes inspection. The top plate and edge angle steel should be welded with weak welds, with the outer side fully welded to a height of 4mm, and no welding on the inner side. The installation of the arch top plate should follow the procedure below: prefabricate and cut the arch top, after the rolled plate passes inspection, assemble and weld on temporary supports, draw the center line of the bottom plate to find the center of the storage tank, first assemble the temporary support columns, and then install the top plate in sections. The height of the arch top should be 50-80mm higher than the design value for the installation of temporary support columns, and the allowable deviation in the verticality of the columns should not exceed 0.1% of the column height, and not exceed 10mm.

The welding of the storage tank is a special process in the construction of storage tanks, and strict adherence to the following requirements is required during construction:

       (1) Before assembling the welds, remove mud, rust, moisture, and oil within a range of 20mm on both sides of the groove surface, and dry thoroughly to expose the metallic luster.

       (2) During welding, ensure the quality of the start and end of the weld, using the back-step arc-start method for the start, and the end should be filled with the arc pit. The joints of multi-layer welds should be staggered.

       (3) All corner joints and overlapping T-joint welds should be completed with at least two passes, with staggered joints, smooth transitions, and at least two passes of welding.

       (4) During tank welding, under the condition of ensuring good penetration and fusion, lower heat input, short arc, and multi-layer welds should be selected, and the inter-layer temperature should not be too high.

       (5) If any of the following conditions occur in the welding environment, effective protective measures must be taken; otherwise, welding is prohibited.

       (6) When manual arc welding, if the wind speed exceeds 8m/s.

       (7) When the wall panel thickness is less than 12mm, use a hand grinder to clean the root on the back side.