GB/T 29890-2026Technical specification for the storage of grains and oilseeds (English PDF)

4.2 Factors to consider when selecting storage technology

4.2.1 Based on climatic and environmental conditions, the country is divided into 7 grain storage ecological zones.

1.High-altitude, arid grain storage area;

---Second Zone. Low-Temperature Dry Grain Storage Area;

3.Low-temperature, high-humidity grain storage area;

4.Medium-temperature dry grain storage area;

5.Medium-temperature and high-humidity grain storage area;

---Section Six. Medium-Temperature, Low-Humidity Grain Storage Area;

7.High-temperature and high-humidity grain storage area. The characteristics of each grain storage ecological region and the main grain storage measures are shown in Appendix A. When selecting the main grain storage measures, the specific regional climate environment should also be considered. The impact of the environment.

4.2.2 Appropriate storage techniques should be adopted based on the following main factors.

---Ecological characteristics of the grain storage ecological zone where it is located;

---Warehouse type and performance of warehousing facilities and equipment;

---Types of grains and oilseeds and their storage characteristics;

---The season in which grains and oilseeds are stored, the quality of the stored grains, the temperature of the grain pile, and the status of pest infestation;

---Expected storage time and intended use.

5.1 Basic Requirements for Warehouses

5.1.1 Appropriate storage processes and facilities and equipment should be set up according to the needs of grain and oilseed storage, transshipment and collection functions.

5.1.2 It shall meet the dynamic and static load requirements for load-bearing grain piles in Building Standard 172-2016, and be able to meet the requirements for moisture-proofing, waterproofing, airtightness, heat insulation, and ventilation of grain storage. Requirements such as wind speed should be taken to reduce the impact of adverse environmental conditions, especially high temperature and high humidity, on grain storage.

5.1.3 Each independent grain and oil storage area should reserve appropriate storage capacity as backup storage capacity.

5.1.4 The floor inside the warehouse should be intact, flat, firm, and equipped with a moisture-proof layer.

5.1.5 The walls of warehouses storing bulk grain and oil should be load-bearing walls.

5.1.6 The interior walls of the warehouse should be intact and smooth with moisture-proof measures, free of cracks, and the joints between the walls and the warehouse roof, adjacent walls, and floor should be tightly sealed. The walls of bulk grain storage silos should be marked with loading lines and height gauges, and sealing grooves should be installed near the loading lines.

5.1.7 The walls of grain silos used for low-temperature or near-low-temperature storage should have good thermal insulation properties, and their heat transfer coefficients should preferably be as follows:

--- Fifth and seventh zones. not greater than

0.52 W/(m^2·K);

---Zones 4 and 6.not greater than

0.58 W/(m^2·K);

---Zones 1, 2 and 3.not greater than

0.70 W/(m2·K).

5.1.8 The roof of the storage area should be intact, with insulation and waterproofing layers, and meet the requirements of relevant design specifications. Roofs with organized drainage should use external gutters. drain. The heat transfer coefficient of the silo roof should preferably not exceed

5.2 Basic Requirements for Facilities and Equipment

5.2.1 The equipment for drying, cleaning, conveying, metering, and grain condition monitoring should be selected and equipped according to the ecological area of the grain storage, the type of storage facility, and the required storage technology. Equipment and facilities for ventilation, refrigeration, controlled atmosphere, fumigation, sampling, and quality inspection. Grain warehouse electromechanical equipment, grain condition monitoring systems, and mechanical ventilation systems. It should comply with relevant regulations.

5.2.2 Dust removal and explosion-proof equipment that conforms to GB 17440 shall be provided.

5.2.3 Lightning protection devices shall be installed in accordance with the provisions of GB 50057.

5.2.4 Large grain warehouses such as tall, flat warehouses and cylindrical warehouses should be equipped with deep sampling equipment.

5.2.5 For zones four through seven, bulk grain storage facilities shall be equipped with recirculation systems that comply with the specifications of GB/T 17913, LS/T 1213, or LS/T 1225. Fumigation or controlled atmosphere storage equipment, such as fumigation and controlled atmosphere storage equipment, should preferably be used in combination with multiple units. Zones 1 to 3 should be equipped with equipment conforming to GB/T 17913. The prescribed circulating fumigation equipment.

5.2.6 Safe, energy-saving, environmentally friendly and automated equipment should be used.

5.2.7 The facilities and equipment of simple warehouses shall comply with the provisions of LS/T 1217.

6.1 Preparations before warehousing

6.1.1 An inspection should be conducted on empty warehouses, equipment, materials, and tools to confirm that there is no damage, leakage, dampness, etc., and that doors, windows, and lighting fixtures are in good condition. It is in good working order and all equipment is functioning properly.

6.1.2 Empty warehouses, storage yards, and work areas should be cleaned thoroughly to remove any residual grains, dust, and debris.

6.1.3 When live insects are found in empty warehouses, packaging materials, grain loading tools, and conveying equipment, insecticides permitted by the state should be used for pest control treatment. Implement isolation measures effectively.

6.1.4 Grain sacks shall comply with GB/T 24904, and woven bags shall comply with GB/T 8946.Wheat flour bags shall comply with... The requirements of GB/T 24905 shall apply. Other packaging shall comply with relevant regulations.

6.2 Quality requirements for grains and oils entering the warehouse

6.2.1 The moisture content should meet the requirements for safe storage.

6.2.2 For raw grains and oilseeds stored for a long period (1 year or more), the quality indicators should meet the relevant national grain and oil quality standards or regulations, and the storage quality should be satisfactory. The indicators should meet the requirements of relevant standards.

6.2.3 The quality indicators of finished grain products shall comply with the relevant national grain and oil quality standards.

6.3 Warehousing Requirements

6.3.1 Raw grains and oilseeds should be stored in separate warehouses according to type and production year.

6.3.2 Raw grains should be stored in bulk. For long-term storage, the grain surface should be leveled.

6.3.3 Grain handling during storage should minimize damage and dust. Multiple methods such as throwing and dropping grain at various points should be adopted during storage to reduce automatic grading and mitigate impurities. Mass aggregation.

6.3.4 Cleaning operations should be carried out outside the warehouse to reduce dust.

6.3.5 Finished grain products should be stored separately according to variety, grade, specification, and production batch, and stacking positions should be marked. The width of the main aisle should preferably be no less than The width of the branch passageway should not be less than 0.6m, and the stack should be at least 0.6m away from walls and columns. Finished grain stacks should facilitate temperature and humidity control, and powdery grains should be stacked in a way that allows for proper temperature and humidity control. Grain should be stored in small stacks.

6.3.6 When stacking packaged grain, the grain bags should be stacked in a staggered manner, with the seams overlapping, neatly and securely arranged, avoiding any tilting. The stacking height should ensure the safety of the grain storage facilities. Personnel safety. Packed finished grain products should be stored on mats.

6.3.7 The height of the grain and oilseeds stored in bulk should not exceed 5m, and the grain stacks should be at least 0.6m away from walls and columns, with appropriate distances maintained between stacks. The stacking height of high-moisture grains should not exceed 3m, and the stacking height of high-moisture oilseeds should not exceed 1m.

6.3.8 Grains and oilseeds that have been infected with pests should be stored separately and treated in accordance with the provisions of

9.1 according to the pest grade.

6.3.9 If pests or diseases listed in the "List of Quarantine Pests for Imported Plants of the People's Republic of China" are found in grains and oilseeds, they should be immediately sealed and... It will be handled in accordance with relevant national regulations.

6.4 Outbound Requirements

6.4.1 When discharging grain from a room-type silo, attention should be paid to the pressure balance on both sides of the silo. When discharging grain from a cylindrical silo, if there is a lower discharge port, it is advisable to discharge from the lower middle section first. Grain should be discharged from the lower grain outlet; other grain outlets should discharge grain evenly and symmetrically, and those without a lower grain outlet should discharge grain symmetrically; grain should be discharged evenly from different silos. Unload to prevent unbalanced loading.

6.4.2 During the unloading operation of a silo, personnel should not enter the silo. If the grain inside the silo becomes brittle or blocked and cannot flow out by gravity, unloading should be stopped immediately. Warehouse operations shall be handled in accordance with relevant regulations.

6.4.3 When grains stored at low temperatures or near low temperatures are taken out of storage during the high-temperature season, measures should be taken to prevent condensation.

7.1.1 Temperature and humidity detection

7.1.1.1 Testing Cycle The temperature and humidity monitoring cycle is as follows:

---When the average grain temperature is < 15°C. Safely stored grains and oilseeds with minimal insect infestation should be tested at least once within 15 days; semi-safe storage... For stored grains and oilseeds or general insect-fed grains, moisture content should be tested at least once within 10 days; for dangerously stored grains and oilseeds, moisture content should be tested at least once within 5 days. Test once;

---When the average grain temperature is >=15°C or the highest grain temperature is >=25°C. Safely stored moisture-rich grains and oilseeds, or grains basically free of insects, should be inspected at least once within 7 days. Test once; for semi-safe storage, test the moisture content of grains and oilseeds or general insect-fed grains at least once within 5 days; for hazardous storage, test the moisture content of grains and oilseeds. The material should be tested at least once a day;

---For newly harvested grains and oilseeds stored for up to three months, in areas with a diurnal temperature range >=10°C, the frequency of testing should be appropriately increased until the grain condition is stable. Stablize.

7.1.1.2 Detection Point Setup The temperature and humidity detection points are set up as follows:

---The establishment of inspection points for bulk grains and oilseeds should be carried out in accordance with the provisions of GB/T 26882.1.Additional points may be added if necessary. The same applies to packaged grains and finished products. Grain quality testing points should be set up according to regulations;

---There should be no lighting fixtures or other heat sources around the testing point;

---For grains and oilseeds with uneven moisture content and impurity distribution, or localized pests, additional mobile temperature and humidity monitoring points should be installed.

7.1.1.3 Test Method Temperature testing of bulk grains and oilseeds shall be performed in accordance with GB/T 22184.Grain temperature, storage temperature, and air temperature shall be measured, and a three-temperature curve shall be plotted. Pay close attention to the highest grain temperature, and the temperature of the surface and edge layers of the grain pile (within 1m of the inner surface of the silo wall). Relative humidity is detected using a humidity sensor within the grain pile; or using a humidity sensor, wet-bulb thermometer, or other hygrometer. The relative humidity of the air inside and outside the chamber was measured.

7.1.1.4 Testing Equipment It should comply with the requirements of GB/T 26882.1.

7.1.2 Moisture Content Detection

7.1.2.1 Testing Cycle The moisture content testing cycle is as follows:

---For safe storage of grains and oilseeds, moisture content should be tested at least once every six months; if abnormal grain conditions are observed, testing should be conducted at least once a month.

---The moisture content of semi-safe stored grains and oilseeds should be tested at least once a month;

---Dangerous stored grains and oilseeds should be tested for moisture every 3 to 5 days, and samples should be taken and tested immediately if an increase in grain temperature is detected.

7.1.2.2 Setting up detection points Perform in accordance with GB/T 5491.

7.1.2.3 Detection Method In accordance with national standards or relevant regulations.

7.1.3 Detection of stored grain pests

7.1.3.1 Testing Cycle The pest density detection cycle is as follows:

---When the grain temperature is above 5°C or below 15°C, it should be tested once a month;

---When the grain temperature is between 15°C and 25°C, it should be measured at least once within 15 days;

---When the grain temperature is above 25°C, it should be tested at least once within 7 days;

---Test at least once every 7 days for 3 months after severe insect-infested food treatment.

7.1.3.2 Sampling Method 7.1.3.2.1 Bulk Grain Sampling Method The sampling points are set as follows:

---For a rectangular grain warehouse, one point is set at each of the four corners, two points are set on the long side of the wall, and one point is set on the short side;

---Points are evenly distributed around the outer perimeter of the circular grain surface; 6 points are distributed for shallow circular silos and large-diameter silos; and 4 points are distributed for the grain surface of vertical silos and underground silos.

---Around the pillars, inside the warehouse doors, personnel entrances and exits, exhaust fan vents, ventilation ducts, points of abnormal temperature changes, and areas where pests have previously occurred. Let there be one point;

---All edge points are 0.1m~0.5m from the wall;

---Depending on the size of the grain pile, 3 to 10 points should be set in the central area of the grain surface;

---Sampling layers within the grain pile are set at 2 to 4 layers according to the height of the grain pile. That is, for grain piles less than 3m high, two sampling layers are set, one at a distance from the bottom. The height of the grain pile should be approximately 0.5m above the grain surface; for grain piles exceeding 3m in height, one to two additional supports should be added at equal intervals between the upper and lower layers. Sample layer. Sampling. Use an electric sampler to sample in layers at each sampling point. The surface layer can be sampled manually. The sample amount at each point in each layer should not be less than 1 kg. The sample taken from each point in each layer is considered as one test point sample. 7.1.3.2.2 Sampling Method for Packaged Grain Sampling point setup. The sampling unit is the storage location. The sampling ratio is determined based on the total number of packages of grain. For packages with less than 500 packages, 10 samples are taken. For packages of 500 or more, determine the sampling package as 2% of the total. Determine the sampling package locations by zone and layer, with more sampling points in the outer layers. (Zoning and stratification) Refer to the principles for setting up sampling points for bulk grain. Sampling. Take samples from inside the package of raw grains. If necessary, unpack or invert the package for sampling. Large grains such as peanuts and broad beans, as well as oilseeds, should be sampled after unpacking. Each sample package should contain at least 1 kg of material. Each sample package serves as the sample for one testing point.

7.1.3.3 Test Method The methods for detecting pests in stored grain are as follows:

---Screening method. Used for determining the insect-fed grade of bulk and packaged grains and oilseeds. Samples collected using insect sieves (7.1.3.2) are sieved... For pests outside the grain, the pest density at that point is represented by the number of live insects sieved out per kilogram of sample (insects/kg).

7.2 Quality Inspection

7.2.1 Quality Inspection Testing is conducted in accordance with relevant national regulations after the product enters the warehouse, before it leaves the warehouse, and during storage.

7.2.2 Storage quality testing

7.2.2.1 Testing cycle. Grains and oils stored through the summer should be tested once each in spring and autumn; grains and oils stored without summer should be tested at least once.

7.2.2.2 Testing methods. Rice shall be tested according to GB/T 20569, corn according to GB/T 20570, and wheat according to GB/T 20571. Okay, soybeans shall be handled in accordance with GB/T 31785, and other grains and oilseeds shall be handled in accordance with relevant national regulations.

8.1 Temperature-controlled storage technology

8.1.1 Grain storage conditions Newly built low-temperature or near-low-temperature grain storage warehouses should meet the performance requirements specified in LS/T 8014; other warehouses should preferably refer to GB/T 26879. In accordance with regulations, heat insulation treatment shall be carried out, and the covers or gates of doors, windows, and all openings directly connected to the warehouse body shall have heat insulation, airtightness, and seepage prevention measures.

8.1.2 Cooling Measures

8.1.2.1 Adopt measures such as natural ventilation, mechanical ventilation, air conditioning, internal circulation temperature control, grain coolers, or other mechanical refrigeration to reduce grain temperature. The temperature of the grain and oilseeds, including overall silo cooling, hot crust cooling of the grain pile, or localized cooling. The performance parameters of the grain cooler should comply with GB/T 18835. In accordance with the provisions of GB/T 29374, the operation of air conditioners and their applications shall be carried out in accordance with the requirements of LS/T 1237.

8.1.2.2 After the grain is stored, during the autumn and winter seasons when the temperature is low, natural ventilation and mechanical ventilation should be used to gradually reduce the grain temperature to below 15°C. (Depending on the local minimum temperature), and take airtight insulation measures such as covering the surface of the grain pile before the temperature warms up. Implement these measures during the warmer seasons. When storing grains at low or near-low temperatures, refrigeration equipment such as grain coolers and air conditioners should be used to control the average grain temperature to below 15°C or 20°C. The following shall be performed in accordance with the provisions of GB/T 44744.

8.1.2.3 During hot seasons, use grain coolers or air conditioners, internal circulation devices, heat exchanger systems, etc., for cooling and humidification. Ventilation, or humidity-controlled ventilation in accordance with GB/T 44963, can reduce the temperature of the entire warehouse, the surface of the grain, or the local area of the grain pile, thus ensuring safe grain storage.

8.2 Grain Storage Ventilation Technology

8.2.1 The function and classification of ventilation Ventilation is used to lower and equalize the temperature of grains or oilseeds, reduce or regulate moisture content, prevent condensation or moisture transfer in grain piles or oilseeds, and discharge pollutants. It removes odors or toxic and harmful gases from grain piles. Based on its function, it can be divided into cooling ventilation, water removal ventilation, conditioning ventilation, and other ventilation methods. Ventilation technologies include natural ventilation and mechanical ventilation.

8.2.2 Natural ventilation

8.2.2.1 Natural ventilation is mainly used for cooling. It is employed when the outside air temperature is lower than the warehouse temperature and the grain temperature, and the relative humidity of the outside air is lower than the equilibrium temperature of the grain pile. Natural ventilation should be used when relative humidity is low and wind speed is between level 3 and 7.

8.2.2.2 It is advisable to dig trenches on the grain surface, open doors and windows, or utilize the ventilation ducts within the grain pile for ventilation. Care should be taken to prevent the grain pile from being exposed due to temperatures dropping below the grain level. Localized condensation caused by point temperature.

8.2.2.3 Packaged grains and oilseeds should be stacked in ventilated stacks.

8.2.3 Mechanical ventilation

8.2.3.1 Vertical ventilation shall be carried out in accordance with the provisions of LS/T 1202; horizontal ventilation shall be carried out in accordance with the provisions of LS/T 1220, and the fan shall meet the requirements. The provisions of LS/T 3549.

8.2.3.2 The intelligent ventilation control system shall comply with the provisions of LS/T 1226.

8.3.1 Nitrogen and carbon dioxide controlled atmosphere storage for grain

8.3.1.1 In sealed grain and oil storage warehouses or grain piles, nitrogen or carbon dioxide is introduced to alter the gas composition of the grain pile in order to control stored grain pests. It kills mites, inhibits mold, and slows down quality decline.

8.3.1.2 The airtightness of controlled atmosphere grain silos shall comply with the requirements of LS/T 1225 or LS/T 1213, and the supporting components of controlled atmosphere grain silos shall comply with... According to GB/T 25229, grain silos that do not meet airtightness requirements should be sealed with plastic film on one, five, or six sides. The plastic film tents used for enclosed grain piles should meet requirements such as high tensile strength, no pollution, no odor, and good airtightness. The adhesive used should have sufficient... The bonding strength is not contaminated.

8.3.1.3 When used to kill pests and mites in various stages, the carbon dioxide gas concentration in the sealed grain pile should reach above 35%, and should preferably be maintained at a certain level. The nitrogen gas concentration should generally reach 98% or higher, and the maintenance time depends on factors such as grain temperature, insect species, and insect development stage; it is generally advisable to maintain it for 30 days or more. above.

8.3.1.4 Nitrogen and carbon dioxide controlled atmosphere operations shall be performed in accordance with the provisions of LS/T 1225 and LS/T 1213, or other controlled atmosphere devices shall be used. Process.

8.3.2 Sealed low-oxygen storage

8.3.2.1 In sealed grain and oilseed piles, low-oxygen (<=12%) storage is carried out using natural oxygen reduction or deoxygenating agents to prevent the spread of disease during grain storage. It kills pests and mites, inhibits mold, and slows down quality decline.

8.3.2.2 The airtightness of sealed grain storage silos shall meet the requirements of controlled atmosphere storage level three or above in GB/T 25229.

8.3.2.3 The moisture content of grains and oilseeds stored in airtight containers shall comply with the regulations for safe storage moisture content.

8.3.2.4 When using plastic film to seal grain piles, it is advisable to place an oxygen absorber under the film to reduce oxygen levels. The oxygen absorber should be permeable. Packed with gaseous materials, it should be recycled after use to prevent it from getting into grain piles.

8.3.2.5 The concentration and time required for low-oxygen control of stored grain pests shall be in accordance with the provisions of GB/T 37491.

8.4 Optimized combination of storage technologies

8.4.1 Low-temperature and low-energy storage After grain or oilseeds are stored in the warehouse, the grain pile is sealed with plastic film. This utilizes the strong respiration during the post-ripening period of the grain or oilseeds to allow the air in the grain pile to breathe. After achieving the desired hypoxic state (oxygen concentration below 12%) and carbon dioxide concentration above 4%, proceed as follows: LS/T 1201 specifies the use of low-effective-concentration phosphine fumigation for insect control or temperature control measures, or "low temperature/quasi-low temperature and low oxygen" or "quasi-low temperature and low oxygen" methods. Low-efficiency phosphine concentration and other dual-low technology for pest prevention.

8.4.2 Low-calorie, low-temperature, and low-carbon storage In autumn and winter, ventilation is used to lower the grain temperature, and measures such as covering the grain surface for insulation are taken to maintain a low temperature in the grain pile for a long time, followed by sealing and cooling. After oxygen storage, pest control shall be carried out by fumigation with the lowest effective concentration of phosphine in accordance with the provisions of LS/T 1201.

8.4.3 Four-in-one storage In grain storage in room-type and silo-type warehouses, an integrated system of grain condition monitoring, mechanical ventilation, recirculating fumigation, and grain cooling technologies and equipment is employed. Its applications include. based on real-time monitoring of grain conditions using information technology, implementing low-effective-concentration phosphine circulating fumigation on newly stored grain. For heat prevention, utilize natural low temperatures for mechanical ventilation in autumn and winter to eliminate the risk of condensation; use airtight insulation to control temperature in spring; and eliminate accumulated heat in summer to achieve normal humidity levels. Safe storage for years.