What are the standard sizes of tower bolts covered in this code?

The standard sizes range from 50 mm to 300 mm in length (Clause 4).

What are the two main types of tower bolts specified?

Barrel type and Skeleton type (Clause 4).

What materials are acceptable for manufacturing these tower bolts?

Components must be made of mild steel conforming to IS 2062 or IS 1079, or suitable free-cutting steel (Table 3).

What is the standard tolerance on the overall length of the bolt?

Tolerance on length is typically +/- 2 mm for smaller sizes and increases slightly for longer lengths as per the dimensional tables.

IS 204

: 2000

Tower Bolts - Specification: Part-1 Ferrous Metals

CurrentFrequently UsedSpecificationBIMArchitectural · Builder Hardware

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This Indian Standard specifies the requirements for materials, dimensions, manufacture, and finish of ferrous metal tower bolts (both barrel and skeleton types) used as builders' hardware. Architects, contractors, and site engineers use this standard to ensure proper sizing, strength, and corrosion resistance for door and window fastenings.

Tower Bolts - Specification: Part-1 Ferrous Metals

Quick Reference Values

Standard lengths of tower bolts50, 75, 100, 125, 150, 200, 250, and 300 mm

Diameter of shoot for bolts up to 125 mm length10 mm

Diameter of shoot for bolts 150 mm length and above12 mm

Minimum thickness of base plate (Barrel Type)1.2 mm

Minimum thickness of base plate (Skeleton Type)3.15 mm

Practical Notes

Always specify the finish (e.g., galvanized, stove enameled, or oxidized) based on the environmental exposure to prevent rusting of ferrous bolts.

Skeleton type tower bolts are generally lighter and more suited for internal doors or windows, whereas barrel types offer more robustness for primary doors.

Ensure the shoot (bolt) diameter matches the load/security requirement; larger doors should use bolts of 150 mm length or more which feature a thicker 12 mm shoot.