Page 25 - Reliability and Maintainability of In service Pipelines

14 Reliability and Maintainability of In-Service Pipelines

The expected service life of drainage pipes is usually between 80 and 100
years, however factors including design methods, loads, installation errors, cli-
mate, and corrosion all affect the service life of these pipes. Installation errors
such as those related to depth and width of burial are usually hard to be pre-
vented. Also, factors such as climate change, which are going to continue having
direct effect on the corrosion process of concrete pipes, can not be prevented eas-
ily (Tran, 2014)
Glass Reinforced Epoxy (GRE) pipes: GRE is essentially a glass fiber that
forms into a polymer. This combination is known as a glass fiber-composite. This
composite is then combined with epoxy resin to make a glass fiber-reinforced
polymer matrix composite, with epoxy resin as a matrix. This combination is clas-
sified as glass reinforced epoxy. The epoxy resin is effective particularly for its
high wetting power and easy adherence to the glass fiber as well as adequate
cohesion strength (Asi, 2009).
Furthermore, epoxy resin does not shrink considerably when setting and also
holds thermal properties. Therefore, using epoxy resin as a matrix in glass fiber
composites increases the likelihood of producing a high strength and weather-
resistant material.
Due to the extensive use of GRE in automobiles, marine, aerospace, and
defense industries, it is evident that GRE is a reliable material, showing character-
istics that are ideal for usage in piping. These characteristics include, corrosion
and chemical resistance, light weight, and extensive service life.
GRE piping also has an efficient strength/stiffness ratio, suggesting that it pro-
vides a good balance if one was to outweigh the other due to external factors
such as loading and weathering and internal factors including flow of materials
and pressure changes. The high temperature resistance (above 125 C) and high

electrical insulation of these pipes also allows use in hot water and industrial
systems.
The ability of GRE pipes to resist thermal expansion also ensures high fatigue
performance in the sense that the structural expansion of the pipe is minimal,
therefore it will have a small effect on pressure changes, flow disruptions, and
turbulences within the pipe which may exacerbate aging of the pipe.

1.3.2.3 Ceramic Pipes

Clay pipes: Clay pipes are generally under the term of “Vitrified” clay pipes,
which is essentially the properties of clay being transformed into a glass-like sub-
stance via application of heat. This transformation makes vitrified clay pipes
harder than steel in terms of structure, however they do not exceed the tensile
strength of steel.
Clay pipes are known for their strength, longevity, and performance in terms
of environmental sustainability. Their strength minimizes the probability of