A 30-inch (750 mm) diameter manhole, a minimum
of one manhole for tanks between 1,000 gallons
(4000 L) and 5,000 gallons (19 000 L)
capacity, and a minimum of two manholes (at
least one 36 inch (900 mm), for tanks larger
than 5,000 gallons (19 000 L) capacity.
A dedicated manhole, other than required
above, as the primary point for piping
penetrations into a tank (may be as small as
22 inches (559 mm)).
Containment sumps and extension manhole.
Roof manholes in accordance with API Std 650.
A minimum of four 24-inch (600 mm) square
inspection hatches on fixed roof tanks with
floating pans and two hatches on all other
tanks. Locate the roof manholes near the
perimeter of the roof at opposite ends of a
diameter and approximately 90E from the shell
Shell manholes in accordance with API Std 650.
Two 36-inch (900 mm) shell manholes 180
degrees from each other. Align shell manholes
parallel with prevailing wind direction.
Hinge-mounted shell manhole covers.
A bolted cover in the roof for installation
and removal of the internal floating pan as
required by the tank supplier based on the pan
Internal ladders (in accordance with OSHA
criteria) for tanks of 5,000 gallons (19 000
L) or larger.
An external ladder and platform with safety
railing for gauging and sampling in accordance
with 29 CFR 1910.23 (if height justifies it).
Vertical Aboveground Storage Tank
Horizontal Aboveground Storage Tank
Horizontal Underground Storage Tank
Aboveground Concrete-Encased Storage Tank
Vertical Underground Storage Tank