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World Cement
North America 2019
The more manpower, equipment, and
expertise needed onsite, the more costly an
inspection can become. This also depends on
how many silos are inspected. Is just one being
inspected or is it six? And for how many days
will the experts be onsite? Will it be one day or
two weeks?
Unfortunately, some customers have let
silo inspections lapse. The result is dozens
or hundreds of silos that must be inspected,
usually at a great cost.
It is suggested that companies plan a rotating
annual inspection programme and configure
that programme so that the problem silos are
observed and inspected more frequently. More
structurally sound silos can go longer without
inspection. In this way, the most economical
programme can be designed and potential
issues caught before they become major
structural or catastrophic problems.
Inspection specialisation
How silos differ from more common structures
is usually related to the unusual load
configurations that must be taken into account,
such as gravity and horizontal loads.
Silos are designed to hold vertical loads
from gravity forces. The design must withstand
internal pressures from materials that are
statically stored, but they must also resist
pressures from materials flowing through the
silo, as well as environmental conditions.
From the start, the key to protecting a silo
is based on proper design and construction.
General engineers are not typically experienced
in the pressure-loading design of silos. Many
inspection reports include cases where
a company has hired a local engineer, a
silo cleaning company (one that only does
cleaning), or a company that is on the periphery
of silo design and construction. However, the
inspection reports from these companies are
expensive and do not address the important
issues that are already understood by silo
contractors. In more than 60% of these cases,
observations provided by those not specialising
in silo construction are not credible and often
require re-inspection. They typically do not
address the true root cause of a problem and
often they do not know the best way to fix what
they find. For example, one customer spent
US$100 000 on an inspection, before being
provided with a report that had no usable
information to help design a repair.
Preventative maintenance
After the periodic inspection of cement silos
is established, the keys to maintaining healthy
and sound silos are cleaning and maintenance.
These keep the cement flowing through the
A thorough inspection of the exterior silo walls
includes visual and other techniques to detect
concealed weaknesses.
Lateral interior loads can stress the silo wall.
Here, a large crack will be closely evaluated
and a repair plan presented to the owner.