1、Length dimensions of steel materials

Length dimensions of steel materials are the most basic sizes of various kinds of steels, which refer to the length, width, height, diameter, radius, inner diameter, outer diameter, and wall thickness, etc. of the steel.The legal units for steel length are meter (m), centimeter (cm), and millimeter (mm). Sometimes it is also expressed in inches (″）, however, it is not a legal unit.

1. Fixed scale of steel materials within a certain rangeItis an effective measure to save materials. Fixed scale within a certain range requires that the length or the product of length and width is not smaller than a certain number, or that the length, or the product of length and width is within a size range. The producer may manufacture and supply the products according to this size requirement.
 
2. Unfixed scale (usually the length)If the size (length or width) of steel is required to be within the defined standard range, while not required as unfixed, the requirement is called an unfixed scale. Unfixed scale length can also be called usual length. Any metal product to be delivered according to unfixed scale can be delivered as long as they are within the defined range of lengths. For example, a commercial round steel of the size no greater than 25 mm can be delivered as long as its length is between 4 m and 10 m, which is its usual length.

3. Fixed scaleIn this situation, the steel must be cut into a fixed size according to the ordering request, which is called the fixed scale. The delivered metal products according to fixed scale must have the same length as is requested in the ordering contract. For example, if the fixed scale length is 5 m in the contract, all the products delivered must be 5-meter long. Any product shorter or longer than 5 m is not qualified. Actually products delivered are always not exactly 5-meters long. Therefore, it is stipulated that the positive deviation is allowed while the negative deviation in no allowed.

4.Multiple scalesIt requires the goods to be cut according to the contract into multiples of a fixed size, which is called a multiple scale. When the products are delivered according to multiple scales, the metal material’s length must be the multiples of the size requested in the ordering contract (single scale). For example, if the single scale length requested in the contract is 2m, it must be 4m long while cut according to double scale, and is 6m long according to triple scale. The length of one or two saw-size should be added, which is stipulated in the standard.

When delivering according to multiple scales, only positive deviations are allowed, while negative deviations are prohibited.

5. Short scaleIf the length is smaller than the lower limit of the defined unfixed scale length, but not smaller than the allowable minimum length, this is called short scale. For example, as stipulated in the standard of steel pipe for water and gas delivery, it is allowable that in every batch there are 10% short scale pipes of length between 2m to 4m, where 4 m is the lower limit of the unfixed scale and the shortest length allowed is 2m.

6. Narrow scaleIf the width is smaller than the lower limit of the unfixed scale but not smaller than the allowable minimum width, this is called narrow scale. While delivering according to narrow scale, we must pay attention to the percentage of the short scale and the narrowest scale stipulated in the standard.

2、Examples of length dimensions of steel

1. Length dimensions of section steels

⑴ Standard length for railway track is 12.5m or 25m.
⑵Dimensions of round steel,wire rod and steel wire are calibrated by the length of their diameter (d) in mm.
⑶Dimensions of square steel are calibrated by the length of its edges (a) in mm.
⑷ Dimensions of hexagonal steel and octagonal steel are calibrated by the distance between their opposite edges (s) in mm.
⑸ Dimensions of flat steel is calibrated by its width (b) and thickness (d) in mm.
⑹ Dimensions of I beam and channel beam are calibrated by the waist height (h), the leg width (b), and the waist thickness (d) in mm.
⑺ Dimensions of equilateral angle iron is calibrated by edge width (b) and thickness (d) in mm. The un-equal angle steel is calibrated by edge width (B, b) and edge thickness (d) in mm.
⑻ Dimensions of H-shaped steel is calibrated by web plate height (h)，wing plate width (b), web plate thickness (t1), and wing plate thickness (t2) in mm.

2. Length dimensions of plate and strip

⑴ It is usually calibrated by plate thickness (d) in mm, while strip by strip width (b) and thickness (d) in mm.
⑵ Each sheet has defined dimensions, for example, for hot rolled steel plate: 1 mm thick plate, there are the following sizes: width 600×length 2000 mm, 650×2000 mm, 700×1420 mm, 750×1500 mm, 900×1800 mm, and 1000×2000 mm, etc.

3. Length dimensions of steel pipes
⑴ Usually, steel pipe is calibrated by its outer diameter (D), inner diameter, and wall thickness (S) in mm.
⑵Each kind of steel pipe has defined dimensions. For example, for seamless steel tubes with an outer diameter of 50 mm, there are 15 different kinds of wall thicknesses ranging from 2.5mm to 10mm; Or, for those with the same wall thickness of 5 mm, there are 29 kinds of outer diameters ranging from 32 mm to 195 mm. Another example: for welded steel pipe with a caliber of 25 mm, there are commercial steel pipe with wall thickness of 3.25 mm, and thickened steel pipe with wall thickness of 4 mm.

3、Weight of steels

1. Theoretical weight of steels

The theoretical weight of steels is obtained by calculating nominal dimensions and density (which is called specific weight in the past). This is directly related with the steel length, the cross section area, and the allowable size deviation. Because of the allowable deviation in the process of manufacturing, the calculated theoretical weight is somehow different from the actual value, and the theoretical value is only for reference while estimating。

2. Actual weight of steels

Actual weight of steel refers to the weight obtained by actual weighting (with a scale). The actual weight is more accurate than the theoretical weight.
   
3. Methods for calculating weight of steels
⑴Gross weight opposed to net weight. It’s the total weight of steel itself and the packing materials. Transportation companies calculate fare based on gross weight, while the purchase and sale of steel is calculated based on net weight.
⑵Net weight opposed to gross weight. It is obtained by subtracting the weight of the packing materials from gross weight. It is the actual weight, called net weight. The purchase and sale are usually based on net weight.
⑶ Tarethe weight of steel products’ packing materials, called tare.
⑷ Ton the weight unit used in calculating carriage by the gross weight of steel. Its legal unit of measurement is ton (1000kg). Besides, there are long ton (British measurement unit, 1016.16kg), and short ton (American measurement unit, 907.18kg)。
⑸ Charged weight also called “the charged ton” or “ the freight ton”. It is the weight of steel for which transportation departments charge. Different ways of transportation have different criterions and methods of calculation. For example, in whole train transportation, usually the charged weight is the marked weight carried by the vehicle. In the highway transportation, it is charged according to the weight capacity of the truck. As for other non-whole train or truck transportation, the minimum charged weight is several kilograms by gross weight. If the weight is a little less than an integral value, it will be calculated by this integral value.