(2) Sizes 80 mm 3 inches through 600 mm 24 inches, cast-iron:
MSS SP-71, Type III or IV, Class 125.
b.
Valves for Class 150 150 poundclass steel piping shall conform to
the following:
(1) Sizes 65 mm 2-1/2 inches and less, bronze:
MSS SP-80, Class
150 minimum.
(2) Sizes 80 mm 3 inches through 600 mm 24 inches, steel:
ASME
B16.34, Class 150 minimum, flanged ends, swing disc.
c.
Valves for Class 300 300 pound class steel piping shall conform to
the following:
(1) Sizes 65 mm 2-1/2 inches and less, bronze:
MSS SP-80, Class
300 minimum.
(2) Sizes 80 mm 3 inches through 600 mm 24 inches, steel:
ASME
B16.34, Class 300 minimum flanged ends, swing disc.
2.19.7.2
Gate Valves
Unless otherwise indicated or specified, gate valves used as shutoff valves
at main headers and elsewhere, as indicated, shall be the chain-operated
type and shall have sufficient chain for easy operation from the operating
floor or walkway. Gate valves 200 mm 8 inches and larger shall be provided
with a globe valve bypass. Gate valves shall be the wedge disc type with
outside screw and yoke and bonnet bushings. Valve body shall have
straight-through ports without recesses except between seats to assure
minimum turbulence, erosion, and resistance to flow. Motor-operated gate
valves shall be installed in the HTW supply and return mains, where
indicated, to isolate the distribution zones from the plant in case of a
line break. The valves shall be closed by a pressure switch operated by
return main water pressure. The pressure switch shall be the Bourdon tube,
actuated mercury switch type with an adjustable operating range of 345 to
2413 kPa 50 to 350 psi. A three-position selector switch shall also be
provided for automatic or manual operation of the valve position.
a.
Valves for Class 125 125 pound class steel piping shall conform to
the following:
(1) Sizes 65 mm 2-1/2 inches and less, bronze:
MSS SP-80, Type 1
or 2, Class 125.
(2) Sizes 80 mm 3 inches through 1200 mm 48 inches, cast-iron:
MSS SP-70, Type I, Class 125, Design OT or OF (OS&Y), bronze trim.
b.
Valves for Class 150 150 pound class steel piping shall conform to
the following:
(1) Sizes 65 mm 2-1/2 inches and less, bronze:
MSS SP-80, Type 1
or 2, Class 150 minimum.
(2) Sizes 80 mm 3 inches through 610 mm 24 inches, steel:
ASME
B16.34, Class 150 minimum, flanged ends.
c.
Valves for Class 300 300 pound class steel piping shall conform to
SECTION 15555A
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