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IS 204:2000 (Part 2) is the Indian Standard (BIS) for tower bolts - specification part-2 non-ferrous metals. This standard lays down the technical specifications for non-ferrous tower bolts, primarily covering brass and aluminium alloy hardware used for fastening doors and windows. It is used by architects and site engineers to ensure the hardware meets standard dimensions, material grades, tolerances, and corrosion-resistant finishes.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Ensure aluminium tower bolts are properly anodized (typically Grade AC 10) to prevent oxidation and ensure longevity, especially in coastal or damp areas.
! Verify the smooth sliding action of the bolt shoot within the barrel during site inspection, as excessive clearance or tightness indicates poor manufacturing tolerance.
! When specifying hardware for heavy-duty exterior doors, prioritize larger diameter shoots (12mm or higher) to prevent bending under forced entry.
Builders hardware - Door and window bolts - Requirements and test methods
Directly covers performance requirements and test methods for door/window bolts, which are the same product category as tower bolts.
ANSI/BHMA A156.16-2018BHMA/ANSI (US)
MediumCurrent
American National Standard for Auxiliary Hardware
Covers a broad range of auxiliary hardware, with a specific section on 'Surface Bolts' which are functionally identical to tower bolts.
Key Differences
≠IS 204 is a prescriptive standard, specifying exact materials (e.g., Mild Steel to IS 2062, Cast Iron to IS 210) and dimensions. In contrast, EN 12051 and ANSI/BHMA A156.16 are performance-based, allowing any material that can meet specified performance criteria for strength, durability, and corrosion.
≠International standards like ANSI/BHMA A156.16 mandate durability testing through mechanical cycling (e.g., Grade 1 requires 100,000 cycles). IS 204 has no such requirement, relying instead on material specifications and workmanship for longevity.
≠EN 12051 and ANSI/BHMA A156.16 use a formal grading/classification system for corrosion resistance based on hours in a Neutral Salt Spray (NSS) test. IS 204 specifies finish types (e.g., zinc plating to IS 1573) but does not mandate a specific duration of salt spray performance for the final product.
≠IS 204 explicitly includes specifications for tower bolts made from grey cast iron (Grade FG 150 of IS 210). Modern international performance standards generally do not specify or encourage cast iron for this application due to its brittleness.
Key Similarities
≈All standards cover the same fundamental product: a manually operated sliding bolt (known as a tower bolt, barrel bolt, or surface bolt) used to secure doors, gates, or windows.
≈All standards are based on the primary use of ferrous metals like steel for manufacturing the bolts, shoots, and staples, acknowledging its strength and suitability for the application.
≈All standards define key dimensional characteristics such as nominal length, bolt/shoot diameter, and plate/staple sizes to ensure fit and function, though the specific values and tolerances vary.
≈All standards recognize the need for protective finishes to prevent corrosion. IS 204 lists specific Indian standards for finishes, while international equivalents link the finish quality to a verifiable corrosion resistance performance test.
Parameter Comparison
Parameter
IS Value
International
Source
Primary Material (Steel)
Mild Steel conforming to IS 2062.
No specific grade mandated; must pass performance tests. Carbon steel is a common material.
ANSI/BHMA A156.16-2018
Primary Material (Cast Iron)
Grey Cast Iron, Grade FG 150 of IS 210.
Not specified; generally not used in modern performance standards for this application.
BS EN 12051:2000
Durability (Cyclic Test)
Not specified in the standard.
10,000 cycles (Grade 1 - Normal use); 25,000 cycles (Grade 2 - High use).
BS EN 12051:2000
Corrosion Resistance (Plated Finish)
Recommends zinc plating to IS 1573, but no salt spray duration is mandated in IS 204.
Grade 3 (moderate resistance) requires 96 hours in Neutral Salt Spray (NSS) test.
BS EN 12051:2000
Classification System
Based on nominal size (length), material (steel/cast iron), and type (straight/cranked).
Performance-based grading (e.g., Grade 1, 2, 3) for durability, finish, and material tests.
ANSI/BHMA A156.16-2018
Shoot (Bolt) Diameter for 150mm Bolt
10.0 mm (min 9.80 mm)
Not explicitly specified; dimension is part of a design that must meet performance tests.
BS EN 12051:2000
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
standard lengths50, 75, 100, 150, 200, 250, and 300 mm
diameter of shoot brass upto 100mm10 mm
diameter of shoot brass 150mm and above12 mm
diameter of shoot aluminium upto 100mm10 mm
anodic coating thickness aluminiumMinimum Grade AC 10 as per IS 1868
Tables & Referenced Sections
Key Tables
Table 1 - Dimensions of Extruded Brass Tower Bolts
Table 2 - Dimensions of Cast Brass Tower Bolts
Table 3 - Dimensions of Extruded Aluminium Alloy Tower Bolts