25 May 2005
Steam boiler water problems (corrosion, deposits, and carryover).
Cooling water problems (corrosion, deposits, and biological).
Closed loop problems (corrosion, deposits, and biological).
Deposits. The term "deposits" refers to a broad categorization of
residues. Deposits are composed of mineral scale, biological matter, and suspended or
insoluble materials (e.g., sludge, dirt, or corrosion byproducts). Deposits can be created
by the attachment of deposit-forming materials to pipe or equipment surfaces, or by
settling and accumulation.
Scale. The term "scale" describes specific types of deposits caused when
mineral salts, dissolved in water, are precipitated either because their solubility limits
have been exceeded or as a result of reaction to water treatment chemicals. Scale
adheres to pipe and equipment surfaces and its formation results in loss of heat transfer
and restricted flow of water or steam. Many different types of scale reflect the quality
and characteristics of the makeup water and the type of chemical treatment being
Biological. The term "biological" describes both macrobiological
organisms (mollusks, clams, fish) and microbiological organisms (algae, fungi, bacteria).
Algae are microscopic plants that may grow in various industrial water systems but most
commonly appear on the distribution decks of cooling towers. Fungi are living
organisms that may cause damage to the wooden parts of cooling towers by causing
the cooling water equipment. Macrobiological organisms can cause fouling problems in
once-through cooling water systems if untreated ("raw") water is used.
Suspended Solids (SS). The term "suspended solids" refers to any
materials present in the water stream that are not actually dissolved in the water. SS
can result from the presence of dirt, silt, and sand in the makeup water or can be
introduced into the water from air in a cooling tower system. Biological matter, both
dead and living, can be a form of SS if carried in the water stream. Corrosion products,
such as iron oxide, are forms of SS that often originate in the system piping.
. The term "corrosion" refers
to metal deterioration resulting
from a refined metal's tendency to return to its original state (i.e., the ore from which the
refined metal was produced). The process of corrosion involves a series of
electrochemical reactions. Metals that contact water in any type of water system can
corrode if there is no attempt to protect them.
Objectives of Industrial Water Treatment. Industrial water is treated to
achieve the following objectives with respect to the equipment in which it is used:
maintaining its efficiency, prolonging its usable "life," and reducing the frequency of
repair or replacement (or both). These objectives can be achieved by treating the water
to prevent scale and to control corrosion, fouling, and microbiological growth. To meet