This specification outlines the standard dimensions and permissible deviations for hot-rolled steel plates intended for ship hull construction. It establishes nominal plate sizes, thickness restrictions, and allowed variations in length and width, ensuring consistent quality and suitability for marine structural applications. The standard serves manufacturers, quality inspectors, naval architects, and other marine industry professionals.
Overview
This specification outlines the standard dimensions and permissible deviations for hot-rolled steel plates intended for ship hull construction. It establishes nominal plate sizes, thickness restrictions, and allowed variations in length and width, ensuring consistent quality and suitability for marine structural applications. The standard serves manufacturers, quality inspectors, naval architects, and other marine industry professionals.
Audience
Contents
Structure
This section defines the nominal dimensions — width, length, and thickness — for hot-rolled steel plates used in ship hull structures. Dimensions are specified in millimeters, and thickness must not exceed the maximum values listed in the reference table for each width-length combination. The table provides maximum permissible thickness limits for various width and length ranges, ensuring plates conform to standard sizes for marine structural use. Rounding of test results follows relevant IS code guidelines.
This part details nominal plate sizes with widths from 900 mm to 3500 mm and lengths spanning 5000 mm to 15000 mm. Maximum allowable thickness decreases as plate length and width increase. The mass of steel plates is calculated using the formula: Mass (kg) = 7.85 × thickness (mm) × area (m²), where 7.85 kg/dm³ is the standard steel density.
The standard specifies thickness tolerances according to plate thickness ranges, with plus and minus limits detailed for various thickness brackets. Width and length tolerances for sheared plates are outlined, varying by plate size and thickness. Edge conditions and tolerance agreements are also discussed, particularly for plates exceeding 32 mm thickness. Measurement points and procedures for thickness verification are described.
Maximum thickness values depend on the plate's width and length combination, with any thickness less than the maximum allowed. Thickness tolerances vary by thickness range, with defined positive and negative limits. Nominal thickness values and corresponding size specifications are standardized to maintain consistency.
Nominal plate lengths range between 5000 mm and 15000 mm, while widths vary from 900 mm to 3500 mm. Maximum thickness decreases with increasing dimensions as per the reference table. Detailed tolerances for width are provided, distinguishing between plates up to 20 mm thick and those thicker, with values expressed in millimeters or percentage of dimension.
Width tolerance limits depend on plate length, width, and thickness, allowing specific positive deviations and no negative tolerance. Length tolerances vary by mill type (continuous or non-continuous) and plate thickness, with defined maximum positive allowances and zero negative tolerance. Special provisions apply for plates thicker than 32 mm.
Defines positive and zero negative tolerances for width based on plate length and thickness categories. For plates thicker than 32 mm, tolerance limits depend on agreements between supplier and purchaser. Thickness tolerance values for various thickness ranges are also summarized.
Length tolerances for plates from non-continuous mills are specified with percentage and fixed millimeter values depending on plate length and thickness. Continuous mill plates with thickness between 5 and 10 mm have a length tolerance of +1% (maximum 70 mm) with zero negative deviation. Thicknesses exceeding 32 mm follow mutually agreed tolerances.
Mass is computed using the nominal steel density (7.85 kg/dm³) multiplied by the plate's thickness and surface area. The formula ensures accurate estimation of plate weight for procurement and structural design purposes.
Specifies rounding rules for test values conforming to the rules of the IS 2:1960 code. Includes measurement points and methods for thickness, width, and length verification to ensure compliance with tolerance criteria.
Guidelines for rounding final test or analysis data according to IS 2:1960 rules, maintaining the precision and significant figures as prescribed in the standard.
Defines nominal size availability, mass calculations, and tolerance agreements for as-rolled and gas-cut edge conditions. Specifies how thickness and dimensional tolerances are applied during supply, emphasizing mutual agreements for plates thicker than 32 mm.
Frequently Asked
As per the standard, hot-rolled steel plates intended for ship hulls are available in nominal thicknesses typically ranging from 3 mm to 100 mm, with common increments such as 3, 4, 5, 6, 8, 10, 12, 15, 20, 25, 30, 40, 50, 60, 80, and 100 mm. Nominal widths usually span from 1000 mm to 3000 mm, with standard widths including 1000, 1250, 1500, 2000, 2500, and 3000 mm. Lengths generally range between 2000 mm and 12000 mm, often customized within this interval. All dimensions comply with the rolling and cutting tolerances stipulated in the standard, with rounding rules applied to maintain uniformity.
Thickness tolerances vary depending on the nominal thickness of the plate. For thicknesses up to 12 mm, a positive tolerance of +7% and a negative tolerance of -0.4 mm apply. Between 12 mm and 15 mm, the plus tolerance is +5% with the same negative limit. For thicknesses from over 15 mm up to 45 mm, the positive tolerance is +4%, while the negative tolerance equals 0.02 times the thickness plus 0.1 mm. For plates thicker than 45 mm, a +4% positive and -1.0 mm negative tolerance apply. Thickness measurements are taken at the four corners, midpoints of the width edges, and midpoints of the length edges, each 50 mm from the edges, ensuring compliance with these tolerance limits.
Width tolerances depend on the plate's length, width, and thickness. For plates up to 20 mm thick and lengths up to 8000 mm with widths up to 2000 mm, the positive width tolerance is +10 mm with no negative tolerance. For widths over 2000 mm within the same length range, the tolerance is +0.5% of the width, zero negative. Plates longer than 8000 mm have width tolerance expressed as +0.2% of length for thicknesses ≤20 mm, and +0.3% for thicknesses >20 mm, with zero negative tolerance. Length tolerances vary by mill type: non-continuous mills allow positive tolerances from +0.5% length to fixed millimeter values depending on length and thickness, with zero negative tolerance; continuous mills for thicknesses 5–10 mm permit +1% length up to 70 mm positive tolerance and zero negative tolerance.
Yes, plates over 20 mm thickness have specific tolerance rules. Length tolerances for these plates depend on the mill type and length range: up to 6000 mm length, tolerances are +0.5% length with zero negative; between 6000 and 8000 mm length, non-continuous mill plates have +0.5% length tolerance, while plates longer than 8000 mm have a fixed +40 mm tolerance, all with zero negative tolerance. Continuous mill plates between 5 and 10 mm thick have a +1% length (maximum 70 mm) positive tolerance and zero negative tolerance. Thicknesses above 32 mm require tolerance agreements between purchaser and supplier.
The mass of steel plates is determined by multiplying the plate's surface area in square meters by its thickness in millimeters, then by the steel's nominal density of 7.85 kg per cubic decimeter. The formula is: Mass (kg) = Length (m) × Width (m) × Thickness (mm) × 7.85. This calculation ensures accurate estimation of plate weight for design and procurement purposes.
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