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 one of the following methods:
a.
Standard roof coupling for threaded pipe up to 150 mm 6 inches in
diameter.
b.
Lead flashing sleeve for dry vents and turning the sleeve down
into the pipe to form a waterproof joint.
c.
A 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.
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: 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
SECTION 15559A
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