Why the Manufacturing Process Determines the Quality of Grain Silos
Global grain production is increasing year by year, and the demand for grain storage is also expanding. Whether it is farmers, grain purchasing enterprises, or large grain and oil groups, they all need reliable storage facilities to ensure food security and reduce losses.
As a widely used grain storage solution, the quality of bolted grain silos is directly related to the storage safety of grain and the service life of the facility. And every detail in the manufacturing process, from design to production to installation, directly affects the durability and safety of the grain silo.
Step 1: Engineering Design And Structural Calculations
manufacturing bolted grain silo, the first step to do is not to produce parts, but combined with customer demand and site conditions, to complete the engineering design and structural calculations – this is the basis of the entire manufacturing process, equivalent to the design drawings of the grain bin.
The capacity of bolted silos can be flexibly customized, from 100 tons to over 20,000 tons can be adjusted, different capacity corresponding to the silo diameter, height and structural design differences are obvious.
Key data on the project site must be collected accurately, which is directly related to structural safety. The wind and snow loads in different areas vary greatly, and the earthquake-prone areas need to be strengthened with earthquake-resistant structures, all of which have to be considered in the design.
Grain silo wall plate adopts the hierarchical design of top thin and bottom thick, the bottom needs to bear all the weight of the grain in the silo, the pressure is the greatest, the wall plate needs to be thicker to ensure the strength; the top pressure is the smallest, it can be appropriately thinned out, not only to protect the safety and save materials.
Foundation load calculation should not be ignored, combined with the total weight of the silo, the weight of the grain, accurate accounting of the foundation to withstand the pressure, to avoid subsequent settlement of the foundation, silo tilt and other issues.
There are two options for the bottom design: funnel bottom is suitable for the scene that needs fast discharging, the grain can flow out automatically by gravity, reducing manual operation; flat bottom is more suitable for the scene with large storage capacity and low discharging frequency, the manufacturing cost is relatively low, and the customer can choose according to the needs.
The design of ventilation and discharging system should be closely integrated with the structure of the silo, the ventilation system can keep the air circulation in the silo to prevent the grain from mold, and the discharging system should guarantee the smooth discharging of the grain to avoid the grain from clogging.
After the design is completed, 3D modeling will be carried out through CAD, Tekla and other professional software to visualize the design scheme, so that it is convenient to check the rationality of the structure and adjust and optimize it in time.
We can provide customized design to ensure that the grain silo meets the project requirements of different countries and regions, to avoid affecting the project advancement due to non-conformity of standards.
Step 2: Selection of high-strength galvanized steel plate
The main structure of the bolted silo is made of steel plate, and the quality of the steel plate directly determines the durability of the silo, so the selection of materials is crucial, and we give priority to the selection of high-strength galvanized steel plate.
Structural steel plate grade is mainly selected S350GD, S450GD or equivalent performance of the steel, this type of steel is the international common high-strength structural steel grade (in line with the EN 10346 standard), widely used in various types of steel structure manufacturing, its tensile strength, yield strength to meet the structural requirements of the silo can withstand the pressure of the grain and the outside world’s natural loads, it is not easy to deformation, fracture. At present, this kind of steel has realized mass production, and can stably supply the demand of international projects.
Galvanized treatment is to enhance the corrosion resistance of the steel plate, to avoid long-term exposure of the steel plate in the air, corrosion by rain and moisture, to extend the service life of the grain silo. The thickness of the galvanized layer is directly related to the service life of the silo. Generally speaking, Z275 galvanized layer can meet the anti-corrosion demand in the conventional environment, and the service life can be up to 15-20 years; Z450 and Z600 galvanized layer is suitable for the more corrosive environment such as humidity, salinity and alkali, and the service life can be extended to more than 25 years.
After the raw materials come in, we will carry out strict inspection to ensure that the quality of steel meets the requirements. The first is the tensile strength test, to detect whether the steel can withstand the design requirements of the tensile force, to avoid the problem of insufficient strength.
Next is the coating adhesion test to check how closely the galvanized layer is bonded to the steel sheet to prevent the galvanized layer from falling off and losing its anti-corrosion effect during use. Finally, the chemical composition analysis should also be carried out to confirm that the chemical composition of the steel meets the standard, to avoid excessive impurities affecting the performance of the steel.
Step 3: Corrugated Wall Plate Roll Molding
Grain silo wall plate with corrugated design, this shape can enhance the structural strength of the wall plate, more than the flat plate wall plate to withstand the pressure, so it is necessary to make corrugated wall plate through the roll molding process.
During production, the whole roll of galvanized steel is first put into the automatic uncoiler to complete the uncoiling and leveling process to remove the wrinkles on the surface of the steel plate and ensure that the steel plate is flat, in preparation for the subsequent molding.
Subsequently, the flattened steel sheet enters the cold roll forming machine, and through the extrusion of the rollers, it is gradually molded into a preset corrugated shape. Cold roll forming does not require high-temperature heating, which preserves the original properties of the steel sheet to the greatest extent possible and avoids high temperatures damaging the strength of the steel and the galvanizing layer.
The core advantage of the corrugated structure is to disperse the pressure. The pressure of the grain on the wall plate inside the silo will be evenly dispersed to the whole wall plate through the curvature of the corrugation, reducing the concentration of local stress and lowering the risk of deformation and breakage of the wall plate.
According to the previous design program, the thickness of the wall plate of different ring layers is different, and the thickness change will be strictly controlled during the production process to ensure that the thickness of each layer of the wall plate meets the design requirements, and the thicker steel plate is selected for the bottom ring layer, and the thinner steel plate is selected for the top ring layer.
At the same time, the dimensional accuracy of the wall panels is strictly controlled, including the spacing of the corrugations, the length and width of the wall panels, and the error needs to be controlled within the permissible range, to ensure that the subsequent on-site assembly of the wall panels can be accurately docked to minimize the difficulty of installation.
We use fully automated roll forming production line, automated operation can not only improve production efficiency, but also ensure that the specifications and shape of each wall plate are consistent, to ensure the stability of the structure of the silo, to avoid errors caused by manual operation.
Step 4: The Bolt Connection Hole Cnc Stamping
The core feature of the bolt-type grain silo is assembled through the bolt connection, so the processing accuracy of the bolt hole directly affects the assembly effect and the sealing of the silo, and this step is also the core of the whole manufacturing process.
We use high-precision CNC stamping machine to process the bolt holes. The CNC equipment can accurately control the position and size of the holes, avoiding the deviation caused by manual stamping, and ensuring that the precision of each bolt hole meets the requirements.
All bolt holes adopt standardized design to ensure that the holes are aligned, so that the bolts can pass through smoothly during subsequent on-site assembly without additional drilling and adjustment, thus improving installation efficiency.
The tolerance of the holes is controlled within ±0.5mm, and this precision ensures that the bolts and holes are closely matched to avoid gaps and prevent rain and moisture from entering the silo, and also ensures the strength of the connection and prevents the bolts from loosening, which affects the stability of the silo.
The stamped bolt holes need to be compatible with the high strength bolt system. We will accurately design the size of the bolt holes according to the specifications of the bolts to ensure that the bolts can be firmly tightened, and at the same time, avoiding the holes to be too big or too small, which will affect the connection effect.
All wall plates and fittings complete the bolt hole stamping in the factory, which belongs to the pre-stamping process, in this way, when assembling on site, you only need to align the parts and tighten the bolts, which greatly shortens the installation time on site and ensures the installation precision at the same time.
Step 5: The Production Of Reinforcing Bars, Wind Ring And Roof Structure
In addition to the main wall plate, the reinforcing bars, wind ring and roof structure of the grain silo are also key components to ensure the strength and safety of the silo body, and need to be produced separately.
Vertical reinforcement is mainly used to enhance the vertical strength of the wall plate, to prevent the wall plate from longitudinal deformation due to the pressure of the grain in the silo, according to the height and thickness of the wall plate, cutting, bending into a pre-set shape, to ensure that the wall plate and the wall plate fit tightly, connecting firmly.
The wind ring is an important part used to enhance the wind resistance of the silo, installed around the silo circumference, can disperse the impact of the wind on the silo, especially in windy areas, the wind ring can effectively prevent the silo from being deformed and damaged by the wind.
The roof structure adopts radial roof plate molding process, the roof plate is radially distributed, spliced into a circular roof, this design can enhance the load-bearing capacity of the roof, and at the same time, it is convenient for drainage, avoiding the accumulation of rainwater on the roof and corrosion of the roof plate.
Roof beams and compression rings are used to support the roof and bear the weight of the roof and external snow loads. Strict control of dimensions and strength is required during production to ensure that the roof can be stably supported to avoid roof collapse.
At the same time, various types of safety accessories, including manholes, ladders, guardrails, etc., have to be produced. Manholes are used for staff to enter the silo for inspection and maintenance; ladders are convenient for staff to climb to the roof or various parts of the silo; guardrails are used to protect the safety of staff and prevent falling from height.
From the performance point of view, we produce bolted grain silos with wind resistance up to 120-160 kilometers per hour, which can cope with strong winds; at the same time, we adopt an integrated seismic structural design, which can adapt to areas with different seismicity levels, and ensure that the silo structure is stable to ensure food security in case of earthquakes.
Step 6: Surface Protection and Quality Inspection
After the production of all components is completed, surface protection inspection and comprehensive quality inspection are required to ensure that each component meets the quality standards and to avoid unqualified components from entering the subsequent stages.
First is the galvanized layer thickness test, using professional equipment to test the galvanized layer thickness of each steel plate, to ensure compliance with the preset Z275, Z450 or Z600 standards (the international general ISO 1461 standard), and for the components with insufficient thickness, they will be re-galvanized to ensure anti-corrosion performance.
Next is dimensional testing, where the dimensions of all components such as wall plates, reinforcement bars, roof plates, etc. are thoroughly checked, including length, width, thickness, bolt hole positions, etc., to ensure that the dimensional accuracy meets the design requirements and to avoid affecting the subsequent assembly.
Then comes the trial assembly test, where some of the key components are pre-assembled to check the docking accuracy of each component, the firmness of the bolt connection, and the sealing of the silo body, and problems are found to be adjusted and repaired in time to ensure that the on-site assembly can be carried out smoothly.
Bolt torque test is also essential to check whether the torque of the bolts after tightening meets the requirements, to ensure the strength of the bolt connection, and to avoid the loosening of the bolts in the process of use, which will affect the stability of the silo.
We adopt a batch numbering system, numbering and marking each batch of components, labeling the specifications of the components, use, production batch and other information, which not only facilitates the subsequent quality traceability, but also simplifies the on-site installation process, and the staff can quickly find the corresponding components according to the number.
In terms of quality control, we strictly follow the ISO quality management system, from raw materials to component production to quality testing, each link has clear quality standards and processes to ensure stable product quality.
At the same time, we support third-party testing, we can invite customer-specified third-party testing organizations to conduct comprehensive testing of product quality and issue test reports, so that customers can rest assured.
Step 7: Modular Packaging and International Transportation
Considering that most of our customers have international project requirements, the packaging and transportation of components need to take into account moisture-proof and damage-proof, as well as optimize the logistics and reduce the transportation cost.
All components will be coded and labeled, each wall plate and each accessory will have a unique code, marking its position in the warehouse, specifications and other information, which is convenient for customers to receive, inventory and assemble on site.
Bolts and all kinds of small accessories will be packed separately and organized into accessory kits according to batches, marking the quantity and specifications of the accessories to avoid loss and confusion during transportation, as well as to facilitate on-site access.
Adopting moisture-proof export packaging, all parts will be wrapped with moisture-proof film and put into moisture-proof packing materials to prevent rusting of steel plate and damage of galvanized layer due to humid environment at sea or rainwater soaking during transportation.
Container loading will be optimized, according to the size and weight of the components, reasonable planning of the placement in the container, maximize the use of container space, reduce the number of containers used, reduce transportation costs.
At the same time, we will carry out cost-optimized logistics planning, combined with the geographic location of the project destination, transport routes, choose the most appropriate mode of transport, taking into account the transport efficiency and transport costs, to ensure that the components can be delivered to the project site on time and safely.
Step 8: On-Site Assembly of Bolted Grain Silos
After the factory completes the production and packaging of the components, all the components will be transported to the project site for on-site assembly, which is a key step in transforming the prefabricated components into complete grain silos.
Before assembly, the foundation preparation and foot bolt installation should be completed first. The foundation should be constructed in accordance with the previous design requirements to ensure that the foundation is level and firm, and the position and height of the foot bolts should be precisely controlled, so as to lay a foundation for the subsequent installation of the silo body.
The installation of the bottom ring layer is the key alignment stage, the bottom wall plate needs to be accurately docked, adjust the verticality and horizontality of the silo body, tighten the anchor bolts to fix the bottom ring layer, to avoid tilting in the subsequent installation.
After the fixing of the bottom ring layer is completed, the bolted assembly of the wall plate is carried out layer by layer in the order from bottom to top, and the alignment accuracy and verticality of the wall plate should be checked for each layer of assembly to ensure that the silo body is overall flat and stable.
After the wall plate assembly is completed, the roof installation is carried out, and the roof plate, roof beams and other components are spliced and fixed in order to ensure that the roof is sealed tightly without water or wind leakage.
The next step is sealing and waterproofing treatment, sealing all the bolted joints, wall plate splicing parts, roof seams, etc. Professional sealing materials are used to prevent rain and moisture from entering the silo and to protect the quality of the grain.
Finally, final testing and commissioning is carried out to check the overall structural stability and sealing of the silo, and to test the operation of the ventilation system and the discharge system to ensure that the silo can be put into use normally.
Compared with welded silos, the advantages of bolted silos are obvious: no on-site welding is required, which reduces the difficulty of on-site construction and construction time; the installation cycle is shorter, and for silos of the same capacity, bolted silos shorten the installation time by more than 30% compared with welded silos.
At the same time, the structure of the bolted grain silo can be expanded, the subsequent need to increase the storage capacity, can be based on the original silo, increase the number of layers of wall plates or splicing of the new silo; long-term maintenance costs are also lower, the components can be replaced individually after the damage, without the need for overall maintenance.
Bolted Steel Plate Grain Silo Manufacturing Cycle
Many customers will be concerned about the manufacturing cycle, in order to plan the project progress, here to introduce you to the conventional manufacturing time nodes, the specific cycle will be adjusted according to the capacity of the grain silo and the complexity of the project.
Engineering design phase, usually takes 7-10 days, mainly including demand docking, site data collection, structural calculations, 3D modeling and program optimization, if the customer has special customization needs, the design cycle may be extended appropriately.
Production stage, the cycle is 15-30 days, the smaller the capacity, the shorter the production cycle; the larger the capacity, the more components, the longer the production cycle, and also consider the time of raw material procurement, quality testing and other links.
There is no fixed standard for the transportation time, which mainly depends on the project destination, the transportation distance and logistic efficiency of different countries and regions are different, and the general international transportation takes 15-45 days.
On-site installation stage, the cycle is 1-4 weeks, small grain silo (100-1000 tons) installation time is shorter, 1-2 weeks can be completed; large grain silo (more than 10,000 tons) more parts, installation time needs 3-4 weeks.
Summarize
The manufacture of bolted grain silo is a systematic project, from design, material selection to production and installation, every step needs to be strictly controlled. The characteristics of factory prefabrication and on-site assembly make it more suitable for international grain storage projects, with both flexibility and practicality. Choosing a professional manufacturer can guarantee the quality of the product and the progress of the project, providing a reliable guarantee for grain storage.