This standard was first issued in 1981. This standard is a revision of GB 2440-1991 "Urea" and GB/T 13257-1991 "Gravimetric method for determination of ash content of industrial urea". This standard specifies the technical requirements, test methods, inspection rules, labeling, packaging, transportation and storage of urea. This standard applies to urea synthesized from ammonia and carbon dioxide, which is divided into two categories: industrial and agricultural. Its main uses are as fertilizers in agriculture and as raw materials for industrial use such as plastics, resins, coatings, and medicines. The main technical differences between this standard and GB 2440-1991 are as follows: 1. The total nitrogen content index, moisture index and particle size index are adjusted in the technical requirements, and the particle size index of large granular urea is added. The particle size range of the particle size item is divided into four grades. 2. GB/T 13257-1991 "Gravimetric method for determination of ash content of industrial urea" is included as Appendix A of this standard for type inspection. 3. The sampling method is modified in the inspection rules. This standard will replace GB 2440-1991 and GB/T 13257-1991 from the date of implementation. GB 2440-2001 Urea GB2440-2001 Standard download decompression password: www.bzxz.net

GB 2440—2001
Chapter 3, Chapter 6 and Article 7.1 of Chapter 7 of this standard are mandatory provisions, and the rest are recommended provisions. This standard is a revision of GB2440—1991 "Urea" and GB/T13257—1991 "Gravimetric method for determination of ash content of industrial urea".
The main technical differences between this standard and GB2440-1991 are as follows: 1. The total nitrogen content index, moisture index and particle size index are adjusted in the technical requirements, and the large particle urea particle size index is added. The particle size range of the particle size item is divided into four grades.
2 GB/T13257—1991 "Gravimetric method for determination of ash content of industrial urea" is used as Appendix A of this standard for type inspection. 3. The sampling method is modified in the inspection rules. Appendix A of this standard is a prompt appendix.
This standard shall replace GB2440-1991 and GB/T13257-1991 from the date of implementation. This standard is proposed by the State Bureau of Petroleum and Chemical Industry. This standard is under the jurisdiction of the National Technical Committee for Standardization of Fertilizers and Soil Conditioners and is responsible for its interpretation. The drafting units of this standard are: National Fertilizer Quality Supervision and Inspection Center (Shanghai), PetroChina Urumqi Petrochemical Company Fertilizer Plant, Sinopec Jiujiang Branch, Hainan Fudao Chemical Co., Ltd. The main drafters of this standard are: Zhang Qiuzhen, Jiang Jianxin, Li Xianjia, Guo, Sha Yanping, Yang Jiqun. This standard was first issued in 1981.
1 Scope
National Standard of the People's Republic of China
GB 2440—2001
Replaces GB2440—1991
GB/T 13257.-- 1991
This standard specifies the technical requirements, test methods, inspection rules, as well as labeling, packaging, transportation and storage of urea. This standard applies to urea synthesized from ammonia and carbon dioxide, which is divided into two categories: industrial and agricultural. Its main uses are as fertilizers in agriculture and as raw materials for industries such as plastics, resins, coatings, and medicines. Molecular formula: CO(NH)2
Relative molecular mass: 60.055 (according to the 1997 International Table of Relative Atomic Masses) 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were all valid. All standards are subject to revision and parties using this standard should investigate the possibility of using the most recent versions of the following standards. GB/T1250-1989 Methods for expressing and determining limit values ​​GB/T 2441.1---2001
Urea determination method Determination of total nitrogen content
GB/T 2441.2-2001
Urea determination method
GB/T 2441.3—2001
Determination of bisphenol A content Spectrophotometric method (neqISO2574:1973)Urea determination method
Determination of water content Karl Fischer method (eqvISO2573:1973) GB/T 2441.4--2001
Urea determination method Determination of iron content O-phenanthroline spectrophotometric method (neqISO6685:1982)
GB/T 2441. 52001
GB/T 2441. 6—2001
GB/T 2441. 7—2001
GB/T 2441. 8--2001
GB/T 2441.9----2001bZxz.net
Urea determination method
Urea determination method
Determination of alkalinityVolumetric method (negISO1593:1977)Determination of water-insoluble matterGravimetric method
Urea determination method
Determination of particle sizeSieving method
Urea determination method
Determination of sulfate content, visual turbidimetric methodDetermination of methylene diurea contentSpectrophotometric methodUrea determination method
GB/T 6679-1986
General rules for sampling of solid chemical products
GB 8569--1997
Packaging of solid chemical fertilizers
Contents and requirements for fertilizer labeling (neqISO7409:1984) GB 18382—2001
3 Requirements
3.1 Appearance: white or light-colored granules.
3.2 The requirements for urea shall comply with the provisions of Table 1. Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on July 26, 2001 and implemented on January 1, 2002
Total nitrogen (N) (on dry basis)
Bis(III)
Water (H,O)
Iron (on Fe)
Alkalinity (on NH)
Sulfate (on SO-)
Water insoluble matter
Methylene diurea (on HCHO)
d 0. 85 mm~2. 80 mm
d 1.18 mm~3. 35 mm
d 2. 00 mm~4. 75 mm
d 4. 00 mm~8. 00 mm
GB 2440—2001
Requirements for urea
Superior quality
First-class quality
If formaldehyde is not added in the urea production process, the determination of methylene diamine content may not be performed. 2 The particle size item in the index only needs to meet any of the four levels, which should be indicated in the packaging label. 4
Test method
Determination of total nitrogen content
Perform in accordance with the provisions of GB/T2441.1.
4.2 Determination of diaminobenzene content
Perform in accordance with the provisions of GB/T2441.2.
4.3 Determination of moisture
Perform in accordance with the provisions of GB/T2441.3.
4.4 Determination of iron content
Perform in accordance with the provisions of GB/T2441.4.
4.5 Determination of alkalinity
Perform according to the provisions of GB/T2441.5.
4.6 Determination of water-insoluble matter content
Perform according to the provisions of GB/T2441.6.
4.7 Determination of particle size
Perform according to the provisions of GB/T2441.7.
4.8 Determination of sulfate content
Perform according to the provisions of GB/T2441.8.
4.9 Determination of methylene disulfide content
Perform according to the provisions of GB/T2441.9.
Qualified products
Superior products
First-class products
Qualified products
5 Inspection rules
GB 2440--2001
5.1 The qualified judgment of the indicators in this standard adopts the "rounded value comparison method" in GB/T1250-1989. 5.2 The products shall be inspected by the quality inspection department of the manufacturer. The manufacturer shall ensure that each batch of products shipped out of the factory meets the requirements of this standard. Each batch of products shipped out of the factory shall be accompanied by a quality certificate in a certain format. The certificate shall include the following contents: manufacturer name, manufacturer address, product name, trademark, product category, grade, particle size, batch number or production date, product net content and this standard number. 5.3 The user unit has the right to conduct quality inspection on the received urea in accordance with the provisions of this standard to verify whether its indicators meet the requirements of this standard.
5.4 The products shall be inspected in batches, with the output of a shift or a day as a batch, and the maximum batch shall not exceed 1500t. The user shall regard the products with quality certificates or received as a batch.
5.For 5-bag products, when the total number of packaging bags is less than 512, the number of sampling bags shall be determined according to Table 2; when it is greater than 512, the number of sampling bags shall be determined according to the calculation result of formula (1). If a decimal is encountered, it shall be rounded up to an integer. Number of sampling bags = 3×N
Wherein: N is the total number of bags of each batch of products.
Table 2 Determination of the number of sampling bags
Total number of bags
82~101
102~125
126151
152~181
Minimum number of sampling bags
Total number of bags
182~216
217~254
255296
297 ~343
344～394
395~450
451~512
Minimum number of sampling
（1）
According to the results of Table 2 or formula (1), randomly select the number of sampling bags, insert the sampler from the longest diagonal line of each bag to three-quarters of the bag to take no less than 100g of sample, and the sample quantity of each batch shall not be less than 2kg. For bulk products, sampling shall be carried out in accordance with the provisions of GB/T6679. 5.6 The sample taken shall be quickly reduced to 600g~1200g of sample using a divider or quartering method according to the different requirements of industrial and agricultural products, and divided into two clean, dry wide-mouth bottles or polyethylene bottles with ground stoppers, sealed, and labeled with the name of the manufacturer, product name, category, batch number, particle size range, sampling date and name of the sampler. One bottle is used for product quality analysis, and one bottle is kept for two months for future reference. 5.7 If one of the indicators in the test results does not meet the requirements of this standard, samples should be taken from twice the number of sampling bags for re-testing. If one of the indicators in the re-test results does not meet the requirements of this standard, the entire batch of products cannot be accepted. 5.8 When the supply and demand parties have objections to the product quality, they should follow the relevant provisions of the "Product Quality Arbitration Inspection and Product Quality Appraisal Management Methods".
6 Labeling
The packaging bag should indicate the particle size range, and the category may not be marked. The rest should be marked according to the provisions of GB18382. 7 Packaging, transportation and storage
7.1 Urea is packaged in double-layer bags or composite plastic woven bags composed of plastic woven bags as the outer bag and polyethylene film bags as the inner bag. The net content of each bag is (25±0.25) kg, (40±0.4) kg or (50±0.5) kg. The average net content of each batch of product bags shall not be less than 359
25.0kg, 40.0kg, 50.0kg.
GB2440—2001
The quality of urea packaging shall comply with the relevant provisions of GB8569. 7.2 Urea can be transported by vehicles, trains, ships and other means of transportation. Transportation tools and loading and unloading tools should be clean, flat, and free of protruding sharp objects to avoid puncturing or scratching the packaging.
7.3 Urea should be stored in a warehouse with a flat, cool, ventilated and dry site. The packages should be stacked neatly and the stacking height should be less than 7m. 7.4 During the transportation and storage of urea, attention should be paid to rain and sun protection. 360
A1 Scope
GB2440—2001
Appendix A
(Indicative Appendix)
Determination of ash content of industrial urea by gravimetric method
This method specifies the gravimetric method for determining the ash content of urea. This method is applicable to the determination of ash content in industrial urea synthesized from ammonia and carbon dioxide. A2 Method Summary
The sample is burned at (800±25)°C, and the residue is expressed as ash content. A3 Apparatus
-General laboratory instruments and
A3.1 Platinum III or quartz crystal, flat bottom, diameter .50mm, height 25mm; A3.2 Box-type high temperature furnace, capable of controlling (800±25)°C. A4 Analysis Steps
Weigh about 100g of sample, accurate to 0.1g, and place in a clean, clean container. Weigh platinum III or quartz crystal (accurate to 0.001g) that has been burned to constant weight at (800±25)℃ and cooled in a desiccator, place it on a low fire in a fume hood, add a small amount of accurately weighed sample, and when it melts, add a small amount of remaining sample until all the sample has been added, melted and partially decomposed.
Transfer the platinum dish or quartz crystal containing the melt to a high-temperature furnace at about 300℃. In order to avoid splashing loss during the heating process, the temperature should be slowly increased to (800±25)℃ (about 1h), and continue heating until the residue is completely burned (about 30min). Take out the platinum crystal or quartz dish, cool it to room temperature in a desiccator, weigh it, accurate to 0.001g, and repeat the burning, cooling and weighing operations until the difference between two consecutive weighings does not exceed 0.0005g.
Note: If the ash content is ≤0.001% or it is used to determine the iron content, platinum crystal should be used. 5 Expression of analysis results
The ash content (X) in the sample is expressed as mass fraction (%) and is calculated according to formula (A1): m2-ml
Wherein: m2-
the mass of the empty platinum blood or quartz dish, g,
the mass of the platinum blood or quartz dish containing ash, g; m21
the mass of the sample, g.
The result should be expressed to five decimal places.
(A1)001% or use it to determine the iron content, platinum blood should be used. 5 Expression of analysis results
The ash content (X) in the sample is expressed as mass fraction (%) and calculated according to formula (A1): m2-ml
In the formula: m,—
The mass of the empty platinum blood or quartz dish, g,
The mass of the platinum blood or quartz dish containing ash, g; m21
The mass of the sample, g.
The result should be expressed to five decimal places.
(A1)001% or use it to determine the iron content, platinum blood should be used. 5 Expression of analysis results
The ash content (X) in the sample is expressed as mass fraction (%) and calculated according to formula (A1): m2-ml
In the formula: m,—
The mass of the empty platinum blood or quartz dish, g,
The mass of the platinum blood or quartz dish containing ash, g; m21
The mass of the sample, g.
The result should be expressed to five decimal places.
(A1)
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