This standard outlines the specifications for hot-rolled steel L-sections intended for shipbuilding, including detailed dimensional criteria, tolerances, and material characteristics to guarantee structural soundness and suitability for marine use. It is relevant for manufacturers, suppliers, and engineers engaged in ship design and construction requiring dependable steel angle profiles.
Overview
This standard outlines the specifications for hot-rolled steel L-sections intended for shipbuilding, including detailed dimensional criteria, tolerances, and material characteristics to guarantee structural soundness and suitability for marine use. It is relevant for manufacturers, suppliers, and engineers engaged in ship design and construction requiring dependable steel angle profiles.
Audience
Contents
Structure
This section defines the applicability of the standard, describing the dimensional and sectional property requirements for hot-rolled steel L-shaped sections used in shipbuilding, including both standard and supplementary sizes as detailed in Tables 1 and 1A.
Explains the format used to denote L-section dimensions: L H × B × t × T, where H is web height, B is flange width, t and T are thicknesses of web and flange respectively, supported by examples and typical values from tables.
Provides detailed dimensions and sectional properties including mass per unit length, leg lengths, thicknesses, fillet radius, cross-sectional area, and moments of inertia necessary for structural design and analysis.
Outlines the material standards and quality criteria for steels used in these L-sections, referencing applicable Indian Standards for structural and shipbuilding grade steel.
Details tolerances allowed on flange thickness, web height, flange width, web thickness, and mass per unit length to ensure conformity during fabrication and quality control.
Describes methods to measure key dimensions and sectional properties, including length, thickness, radius, flatness, and straightness, with instructions on rounding off data as per relevant standards.
Specifies marking requirements for each L-section to include size, mass, manufacturer’s identification, and batch or heat number for traceability and quality assurance.
Lists additional size options beyond the standard range available under mutual agreement with suppliers, including their dimensional and sectional properties.
Explains the procedures for rounding test results, verifying dimensional compliance, and mass tolerances to maintain standard conformity.
Discusses the practical application of hot-rolled L-sections in ship hull framing and structural reinforcements, highlighting critical sectional properties for strength and stability.
Frequently Asked
IS 1864 defines dimensional tolerances for hot-rolled L-sections utilized in shipbuilding, broadly consistent with ISO/DIS 4973. Typical tolerances include leg length variation of ±2 mm, thickness deviations ranging approximately from ±0.3 mm to ±0.5 mm depending on thickness, angular deviation between legs from ±1° to ±2°, and straightness limited to about 1 in 1000 of the length. These tolerances help ensure precise fit and reliable structural performance. For exact figures, the full IS 1864 document or ISO/DIS 4973 should be consulted.
The standard requires L-sections to be fabricated from steels conforming to Indian Standards such as IS 226 (standard structural steel), IS 961 (high tensile structural steel), IS 2062 (fusion welding quality structural steel), or IS 3039 (shipbuilding quality structural steel). The chosen grade depends on purchaser specifications, emphasizing yield strength typically between 250 and 410 MPa, tensile strength ranging from 410 to 560 MPa, weldability, and corrosion resistance suitable for marine applications.
According to IS 1864, straightness is controlled by limiting deviation to a maximum of 0.003 times the length, measured along the entire section with a straight edge. Flatness tolerances for the web are not fixed and must be mutually agreed upon between manufacturer and purchaser. Flatness is typically checked using a steel straight edge to detect any deviations or gaps along the web surface.
The permissible deviation for the angle between the two legs of an L-section is limited to a maximum of 2.5% of the length of the shorter leg, measured at the end of that leg. This ensures the legs maintain near perpendicularity, which is essential for structural integrity and proper assembly.
Yes, IS 1864 provides supplementary sizes in Table 1A, which include less common dimensions beyond the standard range. These supplementary sections can be procured through mutual agreement with suppliers or manufacturers. The purchaser identifies the desired supplementary size and coordinates with the supplier for availability and conformity to the dimensional and mass tolerances specified in the standard.
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