b) For cone roof tanks with floating pans, provide
roof vent/inspection hatches in the fixed roof and overflow
port/vents near the top of the shell near a device(s) in the
floating pan which is (are) sized by the manufacturer to
evacuate air and gases from underneath the pan when the pan is
on its supports during filling operations.
c) Provide grounding bonds between the floating pan
and shell as follows:
(1) Two lengths of bare, 3/16-inch (5 mm)
diameter, stranded, extra-flexible, stainless steel wire rope,
each extending from the top of the floating pan to the
underside of the fixed roof.
(2) Attach two of the wires near the tank
periphery, 180 degrees apart. Attach the third wire to the
floating pan manhole cover.
(3) Securely connect the wires to the pan and
extend vertically to the tank roof. Ensure wires are
accessible for inspection.
(4) Ensure wires are long enough to accommodate
the full travel of the pan. Locate wires to miss all interior
tank appurtenances and structure.
d) Provide antirotation cable in accordance with
Standard Design AW 78-24-27.
e) For cone roof tanks with floating pans, provide
gauge and sampling hatches as described for cone roof, except
that on each hatch provide a gauge well which penetrates the
floating roof through sealed openings and is arranged so that
gauging and sampling can be accomplished from the top of the
tank. Provide a separate well for ATG extending through the
floating pan having the same datum plane as the manual gauge
well. Provide full length slotted stilling well with internal
floating seal and hand operated lifting winch. Construct
stilling wells of aluminum or stainless steel for tanks
storing aviation turbine fuels.
f) Provide a 36-inch (900 mm) diameter covered
manhole in the floating pan.