MIL-HDBK-1022
b) Subject to Paragraph (a), provide minimum depths
in accordance with 49 CFR 195. Under roadways and shoulders
of roadways, provide a minimum depth of 4 feet (1.2 m).
9.3.2
Parallel Pipes. Provide a minimum clearance of 12
inches (300 mm) between the outer wall of any buried pipe and
the extremity of any underground structures including other
underground pipe. In areas where multiple utilities are
routed in the same area (e.g., a utility corridor), make sure
electrical and communication ducts/conduits are kept a minimum
of 36 inches (900 mm) from all other underground utilities
especially fuel, steam, and high-temperature water pipes.
Refer to ANSI C2, ANSI/ASME B31.4, and 49 CFR 195 for
additional requirements. For pipes in concrete trenches,
provide a minimum clearance of 6 inches (150 mm) between
flanges and the trench wall and between adjacent flanges. If
there are no flanges, provide a minimum of 8 inches (200 mm)
between the pipe and the trench wall and between adjacent
pipes within the concrete trench.
9.3.3
Casing Sleeves. Use steel casing sleeves only for
those crossings where sleeves are required by authorities
having jurisdiction, where it is necessary to bore under the
roadway or railroad tracks to avoid interference with traffic,
or where boring is the most economical construction method.
When planning construction of open trench crossings, consider
the economics of installing spare casing sleeves to eliminate
excavating for future fuel lines. Ensure that the design
isolates fuel-carrying pipes from contact with the casing
pipes. Require a seal of the annular space at each end of the
casing. Include a vent on the higher end of each casing.
Locate crossings at a minimum depth of 36 inches (900 mm)
beneath the bottom of drainage ditches. If this depth cannot
be obtained, install above, but not in contact with, the
casing or pipe, a 6-inch (150 mm) thick reinforced concrete
slab of adequate length and width to protect the casing or
pipe from damage by equipment such as ditch graders and
mowers. Refer to API RP 1102 for additional information.
9.3.4
Line Markers. Except where prohibited by national
security considerations, install line markers over each buried
line and allow for maintenance provisions in accordance with
49 CFR 195.
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