recommended by the manufacturer to fit the pipe/conduit and sleeve
involved. The Contractor electing to use the modular mechanical-type seals
shall provide sleeves of the proper diameters.
3.4.1.2
Optional Counterflashing
As alternates to caulking and sealing the annular space between the pipe
and flashing or metal-jacket-covered insulation and flashing,
counterflashing may be accomplished by utilizing standard roof coupling for
threaded pipe up to 150 mm 6 inches in diameter; lead flashing sleeve for
dry vents and turning the sleeve down into the pipe to form a waterproof
joint; tack-welded or banded-metal rain shield around the pipe and sealing
as indicated.
3.4.2
Pipe Joints
Joints between sections of pipe and fittings shall be welded or flanged on
all HTW piping. On auxiliary piping, except as otherwise specified,
fittings 25 mm 1 inch and smaller shall be threaded; fittings 32 mm 1-1/4
inches up to, but not including, 65 mm 2-1/2 inches may be either threaded
or welded; and fittings 65 mm 2-1/2 inches and larger shall be either
flanged or welded. Pipe and fittings 32 mm 1-1/4 inches and larger
installed in inaccessible conduits or trenches beneath concrete floor slabs
shall be welded. Connections to equipment shall be made with black
malleable-iron unions for pipe 50 mm 2 inches or smaller in diameter, and
with flanges for pipe 65 mm 2-1/2 inches or larger in diameter.
3.4.2.1
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
polytetrafluoroethylene tape or equal, applied to the male threads only,
and in no case to the fittings.
3.4.2.2
Welded Joints
Welded joints shall be fusion welded in accordance with ASME B31.1, unless
otherwise required. 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 acceptable. 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 improvement flow where attached to
the run, reinforced against external strains, and designed to withstand
full pipe bursting strength.
a.
Beveling: Field and shop bevels shall be in accordance with the
recognized standards and shall be done by mechanical means or
flame cutting. Where beveling is done by flame cutting, surfaces
shall be cleaned of scale and oxidation before welding.
b.
Alignment: Before welding, the component parts to be welded shall
be aligned so that no strain is placed on the weld when finally
positioned. Height shall be so aligned that no part of the pipe
wall is offset by more than 20 percent of the wall thickness.
Flanges and branches shall be set true. This alignment shall be
preserved during the welding operation. If tack welds are used,
welds shall be of the same quality and made by the same procedure
as the completed weld; otherwise, tack welds shall be removed
SECTION 15555A
Page 88
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