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TOWERS
ACCAT keeps towers in-country for rapid deployment, check out our STOCK LISTING for current availability. Click here for photographs of the tower. Online Stock List

The Andrew Self-Supporting Tower
The Andrew self-supporting three-legged tower has been designed for use throughout Africa and has become the preferred choice of a number of major multinational telecommunications companies.

The tower design was compiled after careful consideration of key factors, such as ease and speed of fabrication, ease of transport, ease and speed of erection and functionality. The solution is a galvanised, all-bolted, triangular, angle sectioned lattice tower that is cost effective with low maintenance requirements.

The tower is unique in that it has a unique patented methodology, which ensures reduced gusset plates and unnecessary points of attachment. It has been stringently tested for performance by Africa’s leading cellular microwave technology integrators.

The tower when put to the test will carry the required loads. Andrew ensures that the tower meets and in virtually all cases exceeds the design requirements for the American, British, South African (all of African standards) and the stringent Canadian standards for design of steel members, welding, use of high tensile bolts and calculations for wind terrain and antenna loading. The quality and grade of steel used in the tower is the highest quality high performance industrial heavy-duty steel.

Manufacturing Process
The Andrew tower is fabricated in South Africa in an ISO 9001 certified factory, which utilizes computer-controlled machines ensuring consistency and quality of product.

‘Prokon’ software was used to analyse the behaviour of the structure under various loading combinations and to determine member sizes. The following materials are used in the construction of the tower:

• Grade 300WA steel
• Grade 8.8 bolts

The efficient production line methodology allows for short fabrication periods leading to ease of supply of bulk orders.

Each tower member is stamped, facilitating part tracking for export applications, and easy reference to key assembly diagrams, allowing simple erection procedures and quality control on site.

All tower sections are supplied galvanised as standard practice. The galvanising is done to high standards meeting local South African specification SABS 0763. When required, a duplex corrosion control system can be supplied where towers are painted as well as being galvanised.

Tower Dimensions
The standard height range offered is from 10m to 92m in 10m intervals, although height variations in steps of 2m for lower towers and 4m for higher towers are available.

Tower strength is categorised as light, medium or heavy duty. This is determined in the design phase with the customer.

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Tower Design
Andrew has developed a computer program called ‘Tower Planner’ to assist the customer with the design process. The software examines the following key factors:

• Height of tower
• Terrain
• Wind speed
• Antenna loading

A typical standard 54m medium duty tower for use by a cellular operator comprises the following design features:

• Standard octagonal concrete foundation for hard soil
• 44m tapered tower section
• upper 10m parallel tower section
• crows nest at 50m for base station antennas
• full internal rest platform at 30m
• internal catladder
• lightning protection
• earthing mat
• navigation lights
• brackets for microwave and base station antennas

Once the design has been agreed and future expansion taken into consideration, the tower can be manufactured.

Foundation
The design of the concrete foundations is provided by Andrew in accordance to the South African specification SABS 0100 (The Structural use of Concrete).

Various design scenarios are used, which are dependent on the soil characteristics of the installation site. Raft or piled foundations being used for soft soil sites.

A typical standard 54m medium duty tower at a hard soil site would need a foundation base area of 8m x 8m.

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Tower Accessories
The following accessories can be provided:

• Navigation lights and cabling
• Lightning protection
• Earthing
• Internal catladder with fall arrest cage and integral feeder cable brackets
• Full internal work platforms
• Rest platforms
• Crows nest for mounting base station antennas

Foundation and Erection Services
ACCAT (Nigeria) Ltd provides a turnkey solution for its customers’ tower requirements. In accordance to Andrew’s strict installation policies and practices, ACCAT uses pre-qualified sub-contractors to undertake civil works, foundation and tower erection.

Andrew’s strict procedures are followed at every stage of the installation process and monitored by ACCAT’s own certified civil engineer. This guarantees that the customer will be handed over a tower that is capable of meeting its current and future needs with minimal maintenance and a life long guarantee.

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Summary of the Key Features of the Andrew Tower

Key Features	Benefits
Triangular Three Legged Tower	Low tonnage Speed of erection Small site footprint Minimised paint surface area
Design Philosophy	Control of twist, sway & rotations Simple selection charts to suit clients needs
No Welding	Minimise quality problems Speed of fabrication
All Bolted Construction	Smaller member lengths simplified packaging & transport
Shaped Angle Legs	Minimise needless fittings Ease of erection Low cost of fabrication
Standard off the Shelf Angle Sections	Speed of delivery Ease of manufacture Low cost No galvanising or corrosion problems associated with ‘pipe’ sections
Angle Section Horizontals	Provides rest platforms at 2m intervals Regular connection points for accessories
Two Metre High Leg Bays	Ease of transport No need for heavy erection equipment

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