3.2.2
Welded Joints
Joints between sections of pipe, between sections of pipe and valves, and
between sections of pipe and fittings shall be welded [except where joints
are allowed to be screwed for pipe sizes 20 mm 3/4 inch and smaller]. The
welding shall conform to the requirements specified in paragraph WELDING.
3.2.3
Flanged and Threaded Joints
3.2.3.1
Flanged Joints
Flanged joints shall be faced true, provided with gaskets, and made
perfectly square and tight. Flanged joints shall be used only for
electrical isolation and in other special cases where connected equipment
is available with only flanged joints, or when specifically shown on the
drawings. Electrically isolated flange joints shall be provided at all
connections to or from the heat distribution system and between dissimilar
metals.
3.2.3.2
Threaded Joints
Threaded joints shall have graphite or inert filler and oil, graphite
compound, or polytetrafluoroethylene tape applied to the male threads only.
Unions shall be provided at all screwed valves, strainers and connections
to equipment 20 mm 3/4 inch and smaller. Dielectric unions shall be used
at connections of dissimilar metals in 20 mm 3/4 inch and smaller piping.
When used on High Temperature Water Systems, threaded joints shall be seal
welded.
3.2.4
Reducing Fittings
Eccentric reducers in horizontal runs shall be installed with the straight
side down. Changes in horizontal piping sizes shall be made through
eccentric reducing fittings.
3.2.5
Branch Connections
Branches from mains shall branch off top of mains as indicated or as
approved. Connections shall ensure unrestricted circulation, elimination
of air pockets, and shall permit the complete drainage of the system.
Branch connections may be made with either welding tees or forged branch
outlet fittings. Branch outlet fittings where used shall be forged and
shall be no larger than two nominal pipe sizes smaller than the main run.
Branch outlet fittings shall be reinforced to withstand external strains
and designed to withstand full pipe bursting strength.
3.2.6
Pipe Supports in Valve Manholes
Horizontal and vertical runs of pipe in valve manholes shall be securely
supported.
3.3
WELDING
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NOTE: If the need exists for more stringent pipe
welding requirements, delete the sentences in the
first set of brackets.
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SECTION 02560
Page 26
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