The IS 204 Part 1 (1991) standard outlines the specifications for tower bolts fabricated from ferrous metals such as mild steel and cast iron. This includes detailed classifications, dimensions, material grades, finishes, marking, packaging, and quality assurance protocols essential for ensuring the bolts meet Indian construction hardware standards.
Overview
The IS 204 Part 1 (1991) standard outlines the specifications for tower bolts fabricated from ferrous metals such as mild steel and cast iron. This includes detailed classifications, dimensions, material grades, finishes, marking, packaging, and quality assurance protocols essential for ensuring the bolts meet Indian construction hardware standards.
Audience
Contents
Structure
This section defines the range of tower bolts covered, including their dimensional specifications, tolerances, and quality control sampling procedures. It references key tables such as dimensions for barrel and skeleton tower bolts and sampling scales for defect acceptance.
Lists related Indian Standards including those for materials like grey iron castings, steel sheets, coatings, and wood screws that are essential for compliance with this specification.
Details the categorization of tower bolts into barrel, semi-barrel, riveted or spot welded, and skeleton types with subtypes. Includes dimensional data tables for each category and requirements for finish and defect-free construction.
Specifies the grades of mild steel and cast iron permitted for manufacturing tower bolts as per relevant Indian Standards, along with certification obligations.
Provides comprehensive dimension tables for various tower bolt types, including bolt lengths, diameters, plate sizes, and minimum screw holes, along with manufacturing tolerances.
Outlines the acceptable tolerances for key dimensions of each tower bolt type to guarantee interchangeability and quality.
Describes acceptable finishing techniques such as bright finishing, nickel-chrome plating, copper oxidation, and zinc plating, ensuring smoothness and removal of sharp edges.
Explains requirements for marking tower bolts with manufacturer identification or trademarks and the optional use of the Standard Mark to demonstrate conformity.
Details packaging methods such as carton packing for barrel bolts and paper wrapping for skeleton bolts, including labeling with manufacture source, type, size, and quantity.
Specifies the sampling plan for lot inspection, permissible defective counts based on lot size, and conditions for lot acceptance or rejection, along with certification requirements.
Enumerates relevant Indian Standards for materials, coatings, and screws referenced for compliance and quality assurance purposes.
Frequently Asked
IS 204 Part 1 permits the use of mild steel sheets complying with Grade 0-1079 of IS 1079:1988 or Grade D of IS 513:1986, mild steel bars of Grade Fe 310-0 as per IS 1977:1975, and cast iron conforming to Grade FG 150 of IS 210:1978. These materials are utilized across various tower bolt types, with mild steel bolts polished bright before assembly and cast iron bolts cast and polished prior to assembly.
The dimensions and tolerances for barrel tower bolts are detailed in Table 1 of IS 204 Part 1, covering parameters like bolt length, barrel length and width, bolt diameter, socket length, sheet thickness, and bore diameter with tolerances such as ±3 mm for length and ±0.5 mm for diameter. Semi-barrel tower bolts follow specifications in Table 2, with similarly defined dimensions and tolerances. Both require defect-free smooth finishes.
According to IS 204 Part 1, each tower bolt must bear a clear mark indicating the manufacturer or trademark. Optionally, the Standard Mark may be applied to signify conformity. Packaging labels for barrel bolts should indicate manufacturer details, bolt type, size, and quantity, typically on cartons. Semi-barrel bolts are bundled and wrapped with corresponding labels specifying the same information.
The standard allows surface finishes such as bright finish, bright stain finish, nickel-chromium plating per IS 1068:1985 Grade 1, copper oxidation as per IS 1376:1987, and zinc plating conforming to IS 1573:1986. Additionally, all edges must be smoothened with no sharp corners, and mild steel bolts should be polished bright before assembly.
Sampling involves selecting a number of bolts from the lot based on its size, as per Table 6 in the standard, with permissible defective bolt counts defined for each lot size range. Bolts are drawn randomly from multiple packets, inspected for dimensional and finish conformity. A lot is accepted if defective counts do not exceed the allowable limits; otherwise, it is rejected. Manufacturers must provide compliance certification.
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