Coatings. In tank coating projects, minimize the
generation of hazardous waste associated with coating removal.
Some alternatives to traditional sand blasting include shot
dioxide, or chemical stabilizer additive process. Designs for
maintenance painting, both interior and exterior, should be
based on a coating condition survey, as discussed in the notes
to NFGS-09971, Exterior Coating for Welded Steel Petroleum
Storage Tanks. An evaluation of shell coating should be based
not only on condition but on the need for coating the shell
and an evaluation of apparent corrosion pressures on the
shell. Corrosion pressure on shell coatings is generally
fairly low; therefore, there is not the same need for coating
thickness and integrity that is required for floors and
ceilings. Refer to Section 8 of this handbook for additional
information on interior and exterior coatings for storage
tanks. Re-coat the portion of the tank that is already
coated. When tanks are taken out of service for inspection or
repairs, inspect the underside of the roof for rust. If
conditions merit, coat the underside of the roof in
conformance with Section 8 of this handbook.
Isolation Valves. Require tank isolation valves to
prevent the accidental release of fuel into the environment.
Provide double block and bleed tank shell valves located
between the tank shell and the high level shut-off valve.
Alarms and High Level Shut-off Valves. Equip
storage tanks with a means to prevent accidental overfill.
Design in accordance with Standard Design AW 78-24-27. Refer
to Section 8 of this handbook for applicable requirements for
alarm and valve installation.
UNDERGROUND OPERATING TANKS. If major
rehabilitation is required, upgrade existing underground
operating tanks to conform with 40 CFR 280 and 40 CFR 281 and
applicable state and local underground storage tank
regulations. As a minimum, provide leak detection, cathodic
protection, and overfill protection. Careful study of cut and
it impossible to comply.
Manholes. Provide a 36-inch (900 mm) diameter
manhole for tanks. Extension necks and internal ladders are
required for cleaning and inspection. Provide a minimum of