2.5.4
Insulating Flanges and Dielectric Waterways
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NOTE: Electrically insulating flanges or dielectric
waterways shall be shown in manholes where piping is
connected to a system that is not cathodically
protected. Insulating flanges and dielectric
waterways must be in accessible locations, such as
valve manholes or buildings.
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2.5.4.1
Insulating Flanges
For systems in which cathodic protection is provided, insulating flanges or
flange gasket kits shall be installed in the valve manhole at the pipe
connection to or from the heat distribution system and at dissimilar metals
and when the carrier pipe and appurtenances are supported in such a way as
to electrically ground or alter the cathodic protection system voltages or
currents. The kit shall consist of flanges, a flange gasket, nuts and
bolts, bolt sleeves, and one insulating washer and one steel washer for
both ends of each bolt. The manufacturer shall certify that the gasket
kits are capable of electrically isolating the pipe at the [_____] kPa psig
pressure and [_____] degrees C degrees F temperature of the heating medium
at the point of application. Evidence of satisfactory installations
operating not less than 2 years shall be submitted in accordance with
paragraph SUBMITTALS before materials are delivered. The Contractor shall
ensure that these kits are provided and properly installed according to
manufacturer's published instructions. Bolts shall be torqued to the
correct tightness and in the correct bolt pattern as recommended by the
manufacturer's published instructions. Steel flanges shall conform to ASME
B16.5 Class [150] [and] [or] [300] and shall match valves or flanged
fittings on which used. Steel flanges shall be flat faced. Gaskets shall
be non-asbestos compressed material in accordance with ASME B16.21, 2 mm
1/16 inch thickness, full face or self centering flat ring type. Bolts
shall conform to the requirements of ASTM A 193/A 193M, Grade B7. The bolt
head shall be marked to identify the manufacturer and the standard to which
the bolt complies. Lengths of bolts shall be such that not less than two
full threads extend beyond the nut with the bolt tightened to the required
tension and the washer seated. Nuts shall conform to the requirements of
ASTM A 194/A 194M, Grade 7.
2.5.4.2
Dielectric Waterways
Dielectric waterways shall have temperature and pressure rating equal to or
greater than that specified for the connecting piping and shall be used for
joining dissimilar metals on 20 mm 3/4 inch and smaller threaded pipe.
Waterways shall have metal connections on both ends suited to match
connecting piping. Dielectric waterways shall be internally lined with an
insulator specifically designed to prevent current flow between dissimilar
metals. Dielectric flanges shall meet the performance requirements
described herein for dielectric waterways.
2.5.4.3
Gaskets Non-Insulating
Provide spiral wound, non-asbestos gasket with centering ring per ASME
B16.20.
SECTION 02560
Page 12
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