High Security Design (Obyek Vital Nasional)

3.1. FENCE

3.1.1 FENCE FABRIC AND CONSTRUCTION REQUIREMENTS

The outer perimeter and some selected facilities are required to be secured by security fence. The fence shall be of sufficient height and construction to present an effective barrier against intrusion. The fence includes anti-climbing devices such as concertina razor coils mounted on top of the fence or/and on the unsecured side of the fence bottom. The basic philosophy to improve the security fence of the selected facilities shall keep the existing access even for operation, maintenance and safety purpose.

FENCE SPECIFICATION
Fence Fabrics
The fence shall be constructed with weld-mesh metal fabric and meet the following minimum specifications:
Welded Mesh Fabrics shall be constructed by resistance welding, high-tensile carbon steel line, (8 gauge) and stay wires together. The wires have a nominal tensile strength of 83,000 psi. (572 Mpa). Hot-dip zinc coated after welding (GAW).

The weld-mesh fence section consists of 2 mm diameter steel wire welded into a grid configuration, with horizontal spacing differing from the vertical spacing. These fence sections are secured to fence posts, to top and bottom rails, and to the adjacent fence panel sections. The sections of weld-mesh fence are either welded together or connected using clips, bolts or rivets.

Anti-climbing Devices
The fence top shall be installed with concertina razor coil and secured by outrigger arrays to prevent casual movement due to environmental conditions. Each coil in the outrigger array shall be taut and tightly secured at each support.
All top-of-fence material and deterrent hardware shall meet the following minimum specifications:
• Any extension arms or outriggers attached to post tops shall have a tight press-fit or shall be spot-welded.
• The extension arms shall be installed on the top of the fence at 45 degree inward and outward as “Y” sharp apron.
• The extension arms as “Y” sharp shall be provided with the “beam” on each arm as a saddle (support) for the concertina razor coil.
Concertina Razor Coil Specifications
• Coil Diameter: 450mm
• Coil Diameter When Stretch: 400mm
• Stretch Length: 10 m
• Spiral Turns Per Coil: 55
• Clips Per Spiral: 3
• Blade Body: 0.5mm Thick Galvanized
• Blade Length: 20 to 25mm
• Blade Width: 19mm
• Wire Body: 2.5mm Galvanized High Tensile Wire

Fence Post
The fence post shall be of 50mm x 50mm x 5mm Galvanized Mild Steel Post (square bar or angle bar) welded to metal foot base and embedded in 300 sq mm concrete footing. Span between two posts shall be 2500 mm (see Figure – 3). For overturning anticipation and stiffness purpose, proper longitudinal and transversal support bracing each 8 spans as a minimum shall be provided.