MIL-HDBK-1005/16
expansion. Therefore, it is critical that proper layout, support,
and restraint be considered to avoid failure.
f)
Pipe Hangers. For all piping systems, specify
pipe hangers that provide maximum corrosion resistance with
little maintenance. Type 304 stainless steel is preferred in
most applications; however, FRP and plastisol-coated carbon steel
may also be used.
12.2.3.2 Gates and Weirs. Gates and weirs should be specified
to provide good performance in immersion applications. Sluice
gates constructed of cast iron materials should be protected with
a proper coating system (par. 12.3.1). Bronze should be
specified for seats and wedges, with Type 304 or 316 stainless
steel for stems, washers, and nuts.
Specify slide gates, weir gates, and weirs as Type 304
stainless steel, aluminum or nonmetallic (FRP). Stainless steel
or nonmetallic material is recommended in applications where
inspection and maintenance may be limited. If aluminum is used,
coat it on surfaces in direct contact with concrete (par. 12.3.1).
Coated steel is not recommended for weirs because of the
difficulty in applying and maintaining paint on the sharp edges.
12.2.4
Electrical Equipment. Electrical equipment located in
aggressive atmospheres within the wastewater treatment plant
should be provided with appropriate corrosion protection or
constructed of resistant materials.
12.2.4.1 Raceways. Raceways in atmospheric and interior
applications may be aluminum, galvanized, PVC, or PVC-jacketed
steel. In wet (humid) process environments, specify PVC or
PVC-jacketed steel. Hardware and accessories should be of
similar materials. Mounting hardware (metal framing support
systems) may be galvanized, aluminum, or PVC jacketed as
appropriate for the service conditions. Repair cut edges of
galvanized or PVC-jacketed materials with the appropriate repair
system. Cable trays may be aluminum or FRP, depending on the
specific exposure.
12.2.4.2 Switchgear and Motor Control Centers (MCCs). Install
switchgears and MCCs in electrical rooms with filtered,
conditioned air sources to minimize exposure to moisture and
hydrogen sulfide. Provide vapor phase inhibitor (VPI) devices in
cabinets, both during the construction period and after operation.
The following materials are suggested for these items:
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