MIL-HDBK-1110
detergent-based) cleaning (SSPC SP 1) is usually adequate for new
galvanizing. This will remove oil applied to the galvanizing to
protect it during exterior storage. If loose zinc corrosion
products or coating are present on either galvanized or
inorganic-zinc primed steel, they should be removed by bristle or
wire brushing (SSPC SP 2 or SSPC SP 3) or water blasting. The
method chosen must successfully remove the contaminants. Uniform
corrosion of unpainted galvanizing may expose the brownish iron-
zinc alloy. If this occurs, the surface should be painted as
soon as possible. If rusting is present on older galvanized or
on inorganic-zinc primed steel, remove the rust by sweep abrasive
blasting (SSPC SP 7) or using power tools, such as wire brushing
(SSPC SP 2, SSPC SP 3). Abrasive blasting is usually more
appropriate when large areas are corroded, while the use of hand
or power tools may be more appropriate when rusting is localized.
For either method, the procedure should be done to minimize
removal of intact galvanizing or of the inorganic zinc primer.
Deteriorated coatings should also be removed using abrasive
blasting or hand or power tools. When leaded-coatings are
present, special worker safety and environmental precautions must
be taken. Refer to Sections 3 and 13.
6.3.5
Aluminum and Other Soft Metals. New, clean aluminum
and other soft metals may be adequately cleaned for coating by
solvent cleaning (SSPC SP 1). The use of detergents may be
required for removal of dirt or loose corrosion products.
Abrasive blasting with plastic beads or other soft abrasives may
be necessary to remove old coatings. Leaded coatings will
require special worker safety and environmental precautions.
6.4
Standards for Condition of Substrates
6.4.1
Unpainted Steel. Verbal descriptions and photographic
standards have been developed for stating the condition of
existing steel substrates. SSPC VIS 1, Abrasive Blast Cleaned
Steel (Standard Reference Photographs) illustrates and describes
four conditions of uncoated structural steel. They are:
Title
Grade
Adherent mill scale
A
Rusting mill scale
B
Rusted
C
Pitted and rusted
D
Since the condition of the surface to be cleaned
affects the appearance of steel after cleaning, these conditions
are used in the SSPC VIS 1 cleanliness standards described below.
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