Quantcast Utility Opening Retrofit Construction

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MIL-HDBK-1013/1A
5.6.6
Window Retrofit Construction.  It may be possible to replace
existing windows with new windows; see par. 5.5.6 for window design options.
As an alternative, elimination of windows will provide enhanced penetration
delay time if the retrofit is accomplished properly.  The most
straightforward method is to seal the window opening with the same
construction used in the wall or building section being sealed.
5.6.7
Utility Opening Retrofit Construction
5.6.7.1
Overview.  In conventional building designs, utility openings,
manholes, tunnels, air conditioning ducts, filters, and equipment access
panels can provide intruders with an attractive entrance or exit route with
no significant delay.  Either such openings must be eliminated or delay times
increased significantly, if consistent physical security integrity of the
overall structure is to be provided.  The following paragraphs provide a
brief description of typical utility openings and the factors and issues that
require special consideration in determining and enhancing delay times.
5.6.7.2
Hardening Utility Openings for Conventional Buildings.  Methods for
hardening utility openings greater than 96 square inches (0.06 sq m) are
described in par. 5.5.6 under New Construction.  These openings include
electrical system conduits, mechanical system conduits for air conditioning,
heating, and venting systems, roof-mounted equipment, filter banks, and
manholes.
5.6.7.3
AA&E Ventilation Openings
1)  Overview.  Door, wall, or roof ventilators in an earth-covered
arms, ammunition, and explosives (AA&E) storage magazine often provide the
best means of penetrating the structure.  Any AA&E ventilator that is 96
square inches (0.06 sq m) or larger must, therefore, be secured against high-
severity level attacks.
2)  Door Ventilators.  Most magazine door ventilators are shrouded,
shrouded and louvered, or simply louvered.  These openings can be quickly and
easily penetrated because of inherent weaknesses in the external mounting,
quality of the mounting, or because, in some cases, the steel of the
ventilator is considerably lighter than the door.  All external shrouds
should be mounted with a continuous bead-weld along all edges.  Many door
ventilators can be reinforced on the inside with riveted steel grating,
MIL-G-18014 Type A, Class B, as shown in Figure 56.  Where design of the door
permits, this cover should be welded flush with the inside of the door.  If
door stiffeners and ventilator frames do not permit flush mounting, this
cover should be offset mounted, using 1/4-inch (6-mm) flat bar or angle steel
at the minimum possible offset.  An alternative to the welding of this grate
to the door is to mount it with 1/2-inch (13-mm) steel bolts and a 1/4-inch
(6-mm) flat bar in the manner shown in Figure 57, with the ends of the
grating extending 6 inches (150 mm) beyond the opening and the bolts and nuts
welded to prevent removal.
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