MIL-HDBK-1005/16
stainless steels should require cleaning and passivating in
accordance with ASTM A380, Standard Practice for Cleaning and
Descaling Stainless Steel Parts, Equipment, and Systems.
12.2.2.4 Handrails and Grating. Avoid painted, carbon steel
handrails and grating because of the high maintenance associated
with these materials. The following guidelines apply to these
items:
a)
Aluminum handrails and gratings are acceptable in
most areas of a wastewater treatment plant. Stainless steel
fasteners and hold-down clips should be used, following the
criteria presented in par. 12.2.2.2. Handrails should be
fastened to floors or walls with cast-aluminum base plates.
Aluminum components should not be cast or embedded in concrete
because the high alkalinity of the concrete will cause
accelerated corrosion of the aluminum. Where aluminum is in
contact with concrete surfaces, it should be coated with a
bituminous coating. Do not use aluminum in any area where lime,
limestone, or sodium hydroxide (caustic) is being handled or
stored.
b)
Stainless steel handrails and gratings are also
acceptable and are used much like the aluminum ones. However,
stainless steel in contact with concrete does not require
coating. Stainless steels may be used in lime and caustic areas.
c)
In chemical handling areas (see par. 12.2.6) use
caution with applications of either aluminum or stainless steel.
The use of fiberglass-reinforced plastic (FRP) is generally
preferred in these applications.
12.2.3
Mechanical Items. Conventional mechanical items may be
used with good performance in most applications in a wastewater
treatment plant. The exception would be in the chemical handling
systems, described in par. 12.2.6, where more corrosion resistant
materials are required.
12.2.3.1 Piping. Nearly every type of piping material has been
used with good success in WTTPs. However, because of the
corrosive conditions that can exist, it is important that the
conditions of service be accurately determined when specifying
pipe materials. In certain installations, it may be a
requirement that double-containment of the piping be required.
This is especially true of chemical transfer lines when they are
buried.
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