trenches beneath concrete floor slabs shall be welded. Connections to
equipment shall be made with black malleable-iron unions for pipe 65 mm
2-1/2 inches or smaller in diameter and with flanges for pipe 80 mm 3 inches
inches or larger in diameter. Joints between sections of copper tubing or
pipe shall be flared, soldered, or brazed.
3.2.6.1
Threaded Joints
Threaded joints shall be made with tapered threads properly cut and shall
be made perfectly tight with a stiff mixture of graphite and oil or with
polytetrafluoroethylene tape applied to the male threads only and in no
case to the fittings.
3.2.6.2
Welded Joints
Welded joints shall be in accordance with paragraph GENERAL REQUIREMENTS
unless otherwise specified. Changes in direction of piping shall be made
with welding fittings only; mitering or notching pipe to form elbows and
tees or other similar type construction will not be permitted. Branch
connections may be made with either welding tees or forged branch outlet
fittings, either being acceptable without size limitation. Branch outlet
fittings, where used, shall be forged, flared for improved flow
characteristics where attached to the run, reinforced against external
strains, and designed to withstand full pipe bursting strength. Socket
weld joints shall be assembled so that the space between the end of the
pipe and the bottom of the socket is no less than 1.5 mm 1/16 inch and no
more than 3 mm 1/8 inch.
3.2.6.3
Grooved Mechanical Joints
Grooved mechanical joints may be provided for hot water systems in lieu of
unions, welded, flanged, or screwed piping connections in low temperature
hot water systems where the temperature of the circulating medium does not
exceed 110 degrees C 230 degrees F. Grooves shall be prepared according to
the coupling manufacturer's instructions. Pipe and groove dimensions shall
comply with the tolerances specified by the coupling manufacturer. The
diameter of grooves made in the field shall be measured using a "go/no-go"
gauge, vernier or dial caliper, narrow-land micrometer or other method
specifically approved by the coupling manufacturer for the intended
application. Groove width and dimension of groove from end of pipe shall
be measured and recorded for each change in grooving tool setup to verify
compliance with coupling manufacturer's tolerances. Grooved joints shall
not be used in concealed locations. Mechanical joints shall use rigid
mechanical pipe couplings, except at equipment connections. At equipment
connections, flexible couplings may be used. Coupling shall be of the
bolted type for use with grooved end pipes, fittings, valves, and
strainers. Couplings shall be self-centering and shall engage in a
watertight couple.
3.2.6.4
Flared and Brazed Copper Pipe and Tubing
Tubing shall be cut square, and burrs shall be removed. Both inside of
fittings and outside of tubing shall be cleaned thoroughly with sand cloth
or steel wire brush before brazing. Annealing of fittings and hard-drawn
tubing shall not occur when making connections. Installation shall be made
in accordance with the manufacturer's recommendations. Mitering of joints
for elbows and notching of straight runs of pipe for tees will not be
permitted. Brazed joints shall be made in conformance with AWS B2.2, MSS
SP-73, and CDA A4015 with flux. Copper-to-copper joints shall include the
SECTION 15569A
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