Recommended Practice for
Home Heating Oil Tank Flood Resistance
Fig. 1 – General photo of assembled
tank and slab before anchoring
- Note all photos are of ½ size
horizontal obrounds tested, but the
hold down methods apply to vertical
obrounds.
National Oilheat Research Alliance 59
Appendix II
This RP is intended to provide recommended installation
guidelines for small heating oil tanks to resist floating
and mitigate spills under severe static flood conditions.
Guidance information of what tank owners should do
before and after flood events occur is also provided.
This RP is intended for use by homeowners, businesses,
oil tank installers, regulators or others who either have
small heating oil tanks on their property, may install
or maintain these tanks or have various government or
regulatory responsibilities for such tanks.
This RP was developed around the most common types
of heating oil tanks typically used in small heating
systems, and reflects practical solutions using widely
available construction components. This RP may also be
used for similar tanks storing similar Class II liquids.
Design Parameters
The following are the heating oil tank and system details
upon which this RP was developed. For tank types,
foundations, hold-downs and flood conditions that differ
from these parameters, a professional engineer should be
consulted to design equivalent flood resistant solutions.
Tank Types:
• Steel UL80 or UL142 obround shapes, max 330 gal.
• Tanks located above ground outdoors or indoors.
• Welded supports or attached legs of min. 1.25" sch 40
steel pipe.
Tank Foundations:
• Existing concrete slabs or structures, such as
garages or patios.
• Concrete slabs designed in accordance with this
RP per (Figure 1).
• Structural steel floors meeting applicable building
code requirements.
Tank Hold-Downs:
• Foot flanges in
combination with
pipe legs per
(Design A1 or A2).
• Concrete anchor
(Design B1 or B2)
in combo with
hold-down (Design
D1 or D2).
• Earth auger
ure(Design C1 or
C2) in combo with
hold-down (Design
D1 or D2).
Flood Conditions:
• Still water in Flood Zones 1-4 with tank at 40% fill
level.
• Flood height of 2.0' above tank shell top for Flood
Zone 1.
• Two day submersion in fresh or salt water.
Miscellaneous Assumptions:
• The tank and supports are in good condition
without damage or corrosion.
• Annual damage and corrosion check of the flood
resistant components used.
• Maintenance or repair of the flood resistant
components if needed.
• All work is done by a licensed contractor.
Disclaimers
Please be aware that the following tanks, installations
or flood conditions are not specifically covered by this
RP:
• Underground tanks of any type, material or size.
• Rectangular steel tanks, and any nonmetallic tanks
(plastic or fiberglass).
• Installations above 1st floor levels or basements one
level below grade.
• Dynamic flood conditions, such as wave action,
storm surge or river flows.
• Excessive wind loads, such as those from tornadoes
or hurricanes.
During severe flood events, such as those
occurring from Hurricane Irene and Super-
Storm Sandy, many coastal and low elevation
inland areas were subjected to high water
conditions. As a result, a number of outdoor above-ground
home heating oil tanks were dislodged and, in some cases,
caused property damage.
In response to the combined effects of these events,
the Oil Heat Institute of Long Island (OHILI) and
the National Oilheat Research Alliance (NORA), in
collaboration with local government agencies and oil heat
industry experts, have developed this Recommended
Practice (RP) in an effort to mitigate these problems in
future flood events.
The research, testing and approval of this RP went
through the National Fire Protection (NFPA) 31
Technical Committee and was balloted successfully for
publication as a reference document.
This RP should be used as guidance when installing
new tanks or upgrading existing installations.
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