NOTE: If coating system similar to coal tar coating
and wrapping is required using different materials,
this paragraph shall be rewritten. If double wrap
system is required, the designer shall remove the
brackets.
**************************************************************************
Bituminous protective system shall be a coal-tar enamel and primer coating
system, and shall consist of a coal-tar priming coat, a coal-tar enamel
coat, a wrapper of coal tar saturated felt, and a wrapper of kraft paper,
or a coat of water-resistant whitewash, applied in the order named and
conforming to the requirements of AWWA C203 in all respects as to
materials, methods of application, tests, and handling, except that an
interior lining shall not be applied. [In addition, where excessively
corrosive soils are encountered, the piping shall be given a second coating
of coal-tar enamel and a second wrapper of felt.] Joints and fittings
shall be coated and wrapped.
3.5.3.2
Polyethylene Pipe Coating
Continuous extruded polyethylene coating and adhesive undercoat application
procedure, including surface preparation, shall be a factory-applied system
conforming to NACE RP0185, Type A. Joints, valves, flanges, and other
irregular surfaces shall be tape-wrapped as outlined under the
tape-wrapping system, except that the tape shall be applied half-lapped,
and all extruded polyethylene coating and adhesive undercoat surfaces to be
tape-wrapped shall be primed with a compatible primer before application of
tape. The primer shall be as recommended by the tape manufacturer and
approved by the applicator of the extruded polyethylene coating. Damaged
areas of extruded polyethylene coating shall be repaired by tape-wrapping
as described under the tape-wrapping system, except that any residual
material from the extruded polyethylene coating shall be pressed into the
break or shall be trimmed off. All areas to be taped shall be primed and
the tape shall be applied half-lapped.
3.5.3.3
Tape-Wrap Pipe Coating
Cleaned surfaces shall be primed before applying tape as recommended by the
manufacturer of the tape. The tape shall be an approved,
pressure-sensitive, organic plastic tape with a minimum nominal thickness
of 0.51 mm 0.020 inch. The tape shall conform to ASTM G 21 for fungus
resistance. Tape shall be applied to clean, dry, grease-free, and
dust-free surfaces only. Weld beads shall be wire-brushed. All burrs and
weld spatter shall be removed. Weld beads shall be covered with one wrap
of tape before spiral wrapping. At each end of straight runs, a double
wrap of one full width of tape shall be applied at right angles to the axis
of the spiral wrapping. Kraft paper protective wrapping, if any, shall be
removed from the pipe before the tape is applied. Material which is
wrapped before it is placed in its final position shall have the wrapping
protected at sling points with roofing felt or other approved heavy
shielding material, or shall be handled with canvas slings. Damaged
wrapping shall be repaired as specified. Pipe in straight runs shall be
wrapped spirally, half-lapping the tape as it is applied. For pipe smaller
than 100 mm 4 inches, one layer half-lapped shall be used. For pipe 100 mm
4 inches and larger, two layers half-lapped shall be used with the second
layer wrapped opposite-hand to the first. Joints, coupling fittings, and
similar units, and damaged areas of wrapping, shall be wrapped spirally
beginning with one complete wrap 75 mm 3 inches back from each edge of the
corresponding size of straight pipe. On irregular surfaces such as valves
SECTION 15559A
Page 104
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