by the manufacturer; backfill adjacent to the tanks shall be pea
gravel unless otherwise recommended by the manufacturer.
Backfill for steel tanks shall be sand.
(2) Set steel tanks on a bed of sand not less than 152 mm 6 inches
deep over the concrete slab and strap in place with stainless
steel hold-down straps with stainless steel turnbuckles. Set FRP
tanks on a bed of pea gravel not less than 305 mm 12 inches thick
and pre-shape for the tank contours for FRP tanks. Fabricate
straps for FRP tanks from FRP resins reinforced with stainless
steel to prevent breaking of straps and floating of empty tanks.
(3) Slope tank toward sump not less than 25 mm in each 1.50 meters
one inch in each 5 feet.]
[b.
Horizontal Fuel Oil Tanks (Above Ground). Continuously support
steel tank saddles along the full length of the base and level and
grout to ensure full bearing.]
[c.
Vertical Fuel Oil Tank. Provide [sand, crushed stone or fine
gravel cushion] [concrete base].]
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NOTE: Choose for a base material either sand/
crushed stone/fine gravel or a concrete base.
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(1) Sand, Crushed Stone or Fine Gravel Cushion: Area beneath
tank shall be covered with a fuel resistant plastic membrane with
a thickness of not less than 0.50 mm 20 mils. Carefully fuse or
cement plastic membrane seams. Lay plastic over a thoroughly
compacted select subgrade free from rocks that could puncture the
plastic. Over the plastic provide a bed of sand, crushed stone or
fine gravel not less than 152 mm 6 inches thick. Stabilize the
bed with an approved material and shape to the tank bottom. Slope
bed down to the center sump approximately 152 mm 6 inches for each
3 meters 10 feet of tank radius. When in place, tank shell shall
be plumb.
(2) Concrete base shall be as indicated and in accordance with
Section 03300N CAST-IN-PLACE CONCRETE.
(3) Mastic Seal: Place the mastic seal between the tank and the
concrete ring to the cross section indicated. Compact the mastic
thoroughly. Immediately before placing the mastic, coat the tank
surfaces to be in contact with the concrete ring with a coat of
MIL-C-18480 bituminous material.
3.1.3
Piping
Unless specified otherwise, erection, welding, brazing, testing and
inspection of piping shall be in accordance with ASME B31.1 and Section
15216N WELDING PRESSURE PIPING. Piping shall follow the general
arrangement shown. Cut piping accurately to measurements established for
the work. Work piping into place without springing or forcing, except
where cold-springing is specified. Piping and equipment within buildings
shall be entirely out of the way of lighting fixtures and doors, windows,
and other openings. Locate overhead piping in buildings in the most
inconspicuous positions. Do not bury or conceal piping until piping has
SECTION 15502N
Page 172
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