2.10.5.6
FS A-A-50558, minimum of Class [125] [150] [250] [300], except as specified
otherwise. [Cast iron], [cast steel] valve body with valve seats and disc
of replaceable heat treated stainless steel. Valves shall be single
seated, shall seat tight under dead end conditions, and shall go to the
closed position in the event of pressure failure of the operating medium.
Valves shall be spring loaded diaphragm operated type, except valves
exposed to ambient temperature of less than 2 degrees C 35 degrees F or
exposed to the weather shall be piston operated type. Capacity of valves
shall be not less than that indicated. Pilot valves shall have strainer at
inlet from external feeder piping.
a.
Spring Loaded Diaphragm Operated Valves: Fabricate main spring of
stainless steel, which shall not be in the path of steam flow
through the valve. Control valve by pilot valve through external
feeder piping.
b.
Piston Operated Valves: Control valve by integral pilot valve
through external feeder piping.
2.10.5.7
Safety Relief Valves
ASME BPVC SEC I ASTM F 1508, Style D or E, with Class [150] [300] inlet
flange, with test lever, designed for the intended service.
2.10.6
Bolts and Nuts
a.
Bolts: ASTM A 193/A 193M, Grade B8. Lengths of bolts shall be
such that not less than two full threads will extend beyond the
nut with the bolts tightened to required tensions and washers
seated.
b.
Nuts:
ASTM A 194/A 194M, Grade 8.
2.10.7
Gaskets
ASME B31.1 and as specified below, except provide spiral wound metal
covered asbestos gaskets in lieu of compressed sheet asbestos. Gaskets
shall be as thin as the finish of surfaces will permit. Do not use paper,
vegetable fiber, rubber, or rubber inserted gaskets for temperatures
greater than 121 degrees C 250 degrees F. Provide metal or metal jacketed
asbestos gaskets with small male and female and small tongue-and-groove
flanges and flanged fittings; they may be used with steel flanges with
lapped, large male and female, large tongue-and-groove, and raised facings.
Provide fullface gaskets with flat-faced flanges. Raised face cast iron
flanges, lapped steel flanges, and raised faced steel flanges shall have
ring gaskets with an outside diameter extending to the inside of the bolt
holes. Widths of gaskets for small male and female and for
tongue-and-groove joints shall be equal to the widths of the male face and
tongue. Gaskets shall have an inside diameter equal to or larger than the
port opening. Dimensions for nonmetallic gaskets shall be in accordance
with ASME B16.21. Materials for flanged gaskets shall be as listed below
for service specified:
a.
Steam, Boiler Blowdown, Exhaust Steam:
Spiral wound metal
composition or copper.
b.
Boiler Feed Water:
Metal jacketed asbestos, copper or monel.
SECTION 15511N
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