Understanding the Evolution and Specifications of Tower Bolts
Foreword
The
Indian Standard for tower bolts, now in its fifth revision, was adopted by the
Bureau of Indian Standards following approval by the Civil Engineering Division
Council and the Builders Hardware Sectional Committee. Initially published in
1950 and revised in 1961, 1966, 1974, and 1978, the standard was bifurcated
during the fourth revision into two parts: Part 1 for ferrous metals and Part 2
for non-ferrous metals. This latest revision introduces necessary updates to
dimensions, practical use, and sampling clauses, aligning with the latest
Indian Standards and international practices. All tower bolts must comply with
these standards, with final values from tests rounded off as specified by IS 2:
1960.
Tower Bolts - Specification
1. Scope
This
standard (Part 2) specifies the requirements for tower bolts made from
non-ferrous metals, including:
- Barrel Tower Bolts:
- Brass barrels with cast or
rolled brass bolts.
- Aluminium barrels with extruded
aluminium alloy sections.
- Zinc barrels with die-cast
zinc alloy.
- Skeleton Tower Bolts:
- Brass skeletons with cast
brass plates and rolled or drawn brass bolts.
- Aluminium skeletons with
extruded aluminium alloy sections.
- Zinc skeletons with
die-cast zinc alloy plates and staples.
2. References
The
Indian Standards listed in Annex A serve as necessary adjuncts to this
standard.
3. Types
- Barrel Tower Bolts: Available in brass,
aluminium, or zinc, featuring various constructions and finishes.
- Skeleton Tower Bolts: Includes brass, aluminium,
and zinc options with specific design requirements.
4. Materials
Materials
for different types of tower bolts must conform to the standards specified in
Table 3 of the standard.
5. Manufacture
Tower
bolts must be well-made, smooth, and free from defects. Sharp edges and corners
should be removed. Where possible, the knob should be integral with the bolt.
For non-ferrous metals, bolts should feature a small spring and ball inside the
barrel to ensure smooth operation.
6. Dimensions and Tolerances
The
dimensions of barrel and skeleton tower bolts must conform to specified
standards, with tolerances outlined in Table 1.
7. Finish
- Brass Tower Bolts: Should be polished or
plated according to standards.
- Aluminium Tower Bolts: Must be anodized to a
specified grade.
- Zinc Tower Bolts: Require oxidation or
plating as specified.
8. Packing
Tower
bolts should be packed in cartons with appropriate labeling. Aluminium tower
bolts need individual wrapping to ensure protection.
9. Sampling and Criteria for Conformity
Sampling
criteria and testing procedures are outlined to ensure conformity. A lot is
considered conforming if the number of defective bolts does not exceed the
allowable number.
10. Marking
Each
tower bolt must be clearly marked with the manufacturer's name or trademark.
The Standard Mark may also be included if applicable.
Conclusion
Understanding
the specifications and standards for tower bolts is essential in the door
hardware industry. Whether you’re sourcing from leading #doorkitmanufacturers
or looking for #doorkitmanufacturersinindia, being knowledgeable about these
details ensures you receive high-quality products that meet industry standards.
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