How much is the negative difference per ton of rebar

10--12 national standards allow 70 kg per ton negative difference, 14--20 allow 50 kg 22-25 allow 40.

Rebar. Rebar is hot-rolled ribbed steel bar.

It is a common name for small section steel.

Steel, mainly used for the skeleton of reinforced concrete building components. In use, it is required to have a certain mechanical strength, bending deformation performance and process welding performance. The raw material billet for the production of rebar is carbon structural steel or low-alloy structural steel that has been calmly smelted, and the finished steel bar is hot-rolled forming and normalizing.

or delivered in hot-rolled condition. The grade of rebar consists of HRB and the minimum yield point of the grade. H, R, and B are the first letters of the three words "hotrolled", "ribbed" and "bars", respectively.

Hot-rolled ribbed steel bars are divided into three grades: HRB335 (old grade is 20mnsi), HRB400 (old grade is 20mnsiv, 20mnsinb, 20mnti) and HRB500.

10--12 national standards allow 70 kg per ton negative difference, 14--20 allow 50 kg 22-25 allow 40.

This depends on the standard of each factory, 10--12 70 kg per ton, 14--20 allowed 50 kg, 22-25 allowed 40 This is the international standard. But there are 3 times the standard ones on the market, and 2 times the general ones.

It depends on which manufacturer. A lot of things are different. Generally, it is not much different from what I said above. That's the range.

Calculation: (.

Weight difference: 6mm 12mm rebar is allowed to have a maximum difference of 7%, 14mm 20mm rebar is allowed to have a maximum difference of 5%, and 22mm 50mm rebar is allowed to have a maximum difference of 4%.

Steel has its international standard, that is, the theoretical weight, according to different models, but the steel we produce is often lighter than this weight, so as to earn the difference, and this difference is the negative difference, also called the lower difference.

The calculation method of negative difference: negative difference = theoretical weight actual weight - 1.

Theoretical weight. The theoretical weight of steel is calculated based on the nominal size and density of the steel (in the past known as specific gravity), and the weight is called theoretical weight. This is directly related to the length dimensions, cross-sectional area and allowable deviation of the dimensions of the steel. Due to the allowable deviation of the steel during the manufacturing process, the theoretical weight calculated by the formula is different from the actual weight, so it is only used as a reference when estimating.

Actual weight: The actual weight of steel refers to the weight of steel obtained by actual weighing (weighing), which is called actual weight. The actual weight is more accurate than the theoretical weight.

(Actual weight - theoretical weight) Theoretical weight = difference. If the actual weight is less than the theoretical weight, it is a negative difference.

For example, you now have a bundle of threads:

The actual weight needs to be weighed.

The theoretical weight is calculated as follows:

The square of the diameter of the rebar * the length * the number of threads in a bundle is the weight of a bundle of threads, the unit of diameter is millimeters, the unit of length is meters, and the unit of weight is kg, and the diameter of the threads usually sold in the market is 10, 12, 14, 16, 18, 20, 22, 25, 28, 30, etc. The units are all millimeters.

Actual weight Theoretical weight * = negative difference %

Calculation formula: diameter * diameter *

The correct name of rebar is hot-rolled ribbed steel bar, and its national standard is "GB T steel for reinforced concrete Part 2: hot-rolled ribbed steel bar", and the allowable tolerances of each specification are different, see the following table:

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Weight difference: 6mm 12mm rebar is allowed to have a maximum difference of 7%, 14mm 20mm rebar is allowed to have a maximum difference of 5%, and 22mm 50mm rebar is allowed to have a maximum difference of 4%. The specification requirements for rebar should be set out in the import and export ** contract.

Generally, it should include the standard grade (type code), the nominal diameter of the rebar, the nominal weight (mass), the specified length and the tolerance value of the above indicators. China's standard recommends a series of rebar with a nominal diameter of mm. The length of supply is divided into two types: fixed length and double ruler.

China's export rebar sizing sizing selection range is 6 12m, and the sizing range of Japanese rebar is; If there is no requirement in the contract, the domestic rebar is usually fixed to 9m and 12m in length.