2.6
VALVES
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NOTE: Select the appropriate valves for the
operating temperatures and pressures of all systems
in the project. Delete valve types not included in
project.
Use not less than Class 150 for up to 862 kPa (125
psig) steam, and not less than Class 300 for 863 kPa
to 1724 kPa (126 to 250 psig) steam and high
temperature water. For isolation and shutoff, use
gate valves only. Steam pressure reducing valves
are not normally part of the system. If needed,
designer should refer to Section 15559A CENTRAL
STEAM-GENERATING SYSTEM, COAL-FIRED or Section
15183N STEAM SYSTEM AND TERMINAL UNITS for Navy jobs.
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Unless otherwise specified, valves shall comply with the material,
fabrication, and operating requirements of ASME B31.1. Valves shall be
suitable for the temperature and pressure requirements of the system on
which used. Valves for [steam] [hot water] shall conform to ASME B31.1
Class [150] [and] [or] [300], as suitable for the application. [Valves for
condensate services shall conform to ASME B31.1 Class 150.] Valves 20 mm
3/4 inch and smaller may be bronze where seal welding is not required.
Valves 150 mm 6 inches and larger shall have a 25 mm 1 inch minimum gate or
globe bypass valve sized in conformance with MSS SP-45.
2.6.1
Steel Valves
Steel globe, gate, angle, and check valves shall conform to the
requirements of ASME B16.34 and ASME B31.1 for the temperature and pressure
requirements of the system. Gate valves 65 mm 2-1/2 inches and smaller
shall be rising stem. Gate valves 80 mm 3 inches and larger shall be
outside screw and yoke.
2.6.2
Bronze Valves
2.6.2.1
Globe, Gate, and Angle Valves
Bronze globe, gate, and angle valves shall conform to requirements of MSS
SP-80, union bonnet type.
2.6.2.2
Check Valves
Bronze check valves shall conform to the requirements of MSS SP-80.
2.6.3
Packing
Packing used with valves shall not contain asbestos. Valve stem packing
shall be die-formed, ring type specifically designated as suitable for the
temperature and pressure of the service and compatible with the fluid in
the system. Packing shall be polytetrafluoroethylene with minimum 50
percent graphite filament. Valves 40 mm 1-1/2 inches and smaller shall
have four or five packing rings and valves 50 mm 2 inches and larger shall
have at least six packing rings. Spiral or continuous packing will not be
acceptable. A metal insert shall be provided having proper clearance
around the valve stem at the bottom of the stuffing box and acting as a
SECTION 02560
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