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Description / Abstract:
This standard provides a procedure that shall be used to (1)
identify electric transmission, distribution, and substation
structures that may be at higher risk for below-grade coating
degradation; (2) excavate and inspect the selected structure; (3)
assess the level of risk to the structure in terms of corrosion
attack and degradation to the existing coating system; (4)
prioritize structures to be repaired based on those findings as to
whether coating repair is needed and if so, to what extent; and (5)
apply repair coatings to the structure, if applicable.
This standard is limited to assessment and repair of coating
applied below grade and in the transition zone portions of carbon
steel and galvanized steel electric transmission towers, grillage,
and substation structures. It does not address assessment and
repair of coatings above the transition zone. For the purposes of
this standard, this area comprises of the below-grade portion, the
transition zone, and is defined as that portion of the coating
exposed up to 600 mm (24 in) above grade.
This standard does not address structural damage assessment,
structural repairs, weathering steel, or structural integrity. This
standard does not address concrete foundations or above-grade
attachment points including anchor rods, attachment nuts, and
noncoated ground sleeves. This standard does not address continuous
immersion environments. This standard does not provide guidelines
and repair procedures for coating systems for every specific
situation because of the complexity and diverse nature of
conditions to which buried structures may be exposed.
Purpose—This standard provides guidelines and repair procedures
for coating systems most commonly applied to belowgrade electric
transmission structures and typical of what inspection and coating
repair crews most often find.