Page 180 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

158 CORROSION CAUSES

must be protected from human and weather factors in order for their operation to
be executed in a reliable way over a long period of time. According to an expert
in electronics, manufacturing and corrosion failures of this type of equipment are
caused by environmental factors such as moisture. Corrosion of the delicate small
parts can cause malfunction of the equipment.
Most of the telecommunication hardware is placed and used in buildings and thus
not exposed to corrosive atmosphere. In addition, electronic hardware has a limited
lifetime and becomes obsolete in a few years. The actual service life of consumer is
often limited by rapid technological changes rather than material degradation issues.
Telecommunication equipment with a longer design life consists of cables, con-
nectors, and antennas for the transmission and reception of electronic signals. These
components may be placed and buried so that they become exposed to environments
such as soils and water or they may be exposed to air and moisture conditions. There
is no report on the percentage of failures because of corrosion for each category.
A specific corrosion problem is a possibility at telephone facilities that maintain
backup power systems in case of power outages. These facilities may have diesel
fuel generators supplied by USTs. A leaking UST system can lead to contamination
of ground water supplies and can cause fires, explosions, and vapor hazards. Under
the Resource Conservation and Recovery Act (RCRA) for USTs, the owners and
operators of USTs must have upgraded, replaced, or closed existing substandard UST
systems by December 22, 1998. Upgrading may involve adding spill, overfill, and
corrosion protection to the UST system.

3.16.1 Shelters
Telecommunications equipment is usually housed in a shelter to protect it from wind
and foul weather. Shelters are structures without windows that can be climate con-
trolled and contain a large amount of electronics, computers, and other equipment
such as transformers.
Shelters are generally located in the immediate vicinity of power stations and com-
munication towers. Many antennas and towers are placed at high locations; therefore,
shelters are located on rooftops. Shelters are also placed at locations on the ground.
The mobile telephone system requires many support antennas spread throughout the
landscape. Along a major interstate highway, it is possible for one to count nearly
one communication tower per one mile of highway. Each tower is protected with a
shelter and a fence around it, both of which protect the infrastructure.
Four construction materials are used for communication shelters: steel, aluminum,
fiberglass, and concrete. Wooden blocks or concrete block are used for the founda-
tions of shelters.
Carbon steel shelters need to be painted to protect them from corrosion. Stainless
steel shelters do not require to be painted, but are more expensive than carbon
steel shelters. Aluminum has favorable weight-to-strength ratio. On roof tops
and on other mounted structures, the dead weight of the shelter can be important
for structural purposes. Aluminum is generally corrosion-resistant in nonmarine
environments. Aluminum is costlier than carbon steel and requires no painting.