I. Key Parameters for the Weight of a Single Coil
The weight of a coil is not a fixed value and must be calculated based on the following four parameters:
1. Material Density: Ordinary carbon steel has a density of 7.85 tons/cubic meter, while stainless steel (such as 304) has a density of 7.93 tons/cubic meter.
2. Dimensions:
- Thickness (mm): Commonly 0.5-20 mm
- Width (mm): Mostly 1000-2000 mm
- Outer Diameter (mm): Typically 800-2000 mm
- Inner Diameter (mm): International standard is 508 mm (20 inches) or 610 mm (24 inches)
3. Calculation Formula:
$$Weight (tons) = \frac{π × (outer diameter² - inner diameter²) × width × density}{4 × 10^9}$$
4. Reference Values:
- Thin plate (1 mm thick × 1250 mm wide): Approximately 3-5 tons/roll
- Medium plate (10 mm thick × 1500 mm wide): Approximately 15-20 tons/roll
- Extra thick plate (20 mm thick × 2000 mm wide): Up to 25-30 tons/roll
(Data source: GB/T 708-2019 "Dimensions, Shape, Weight, and Tolerances of Cold-Rolled Steel Sheet and Strip"
II. Practical Factors Affecting Weight
1. Differences in Production Standards:
- Hot-rolled coil is heavier than cold-rolled coil (10%-15% heavier for equivalent dimensions)
- Japanese International Standard (JIS) coils typically use an inner diameter of 610mm, which differs from the national standard.
2. Transportation and Storage Restrictions:
- Road transport of a single coil typically does not exceed 25 tons (subject to vehicle load limits).
- The maximum load capacity of port lifting equipment is generally 30 tons per coil.
3. Special Industry Requirements:
- Galvanized coils for automotive use: 5-8 tons per coil (needs to accommodate automated production lines)
- Color-coated coils for construction use: 10-15 tons (considering both transportation and construction efficiency).
III. User FAQs
1. How can I get a quick estimate?
Simple formula: Weight per ton ≈ 0.00617 x Thickness (mm) x Width (m) x Coil Length (m)
Example: A coil of 2mm thick, 1.5m wide, and 1000m long weighs ≈ 18.5 tons.
2. Why do coils of the same specification weigh different weights?
- Positive and negative tolerances (e.g., a 3mm coil might actually weigh 2.8-3.2mm)
- Coil tightness causes variations in outer diameter.
3. How are special materials calculated?
- Aluminum coil (density 2.7): Weight is only 34% of that of a steel coil of the same volume.
- Copper coil (density 8.9): 13% heavier than a steel coil