of code, ASME CSD-1, Controls and Safety Devices for Automatically Fired
2.3.1.3
Feed and Check Valves
Feed and check valves shall be provided adjacent to each boiler feed nozzle.
2.3.1.4
Continuous Blowdown Valve
**************************************************************************
NOTE: Continuous blowdown equipment will be
provided as required by TM 5-810-1. If a fire-tube
boiler is specified, these paragraphs will be
deleted.
**************************************************************************
Continuous blowdown valves shall be manual proportioning, fabricated of
corrosion-resistant steel. Valves shall have a micrometer dial setting and
shall be provided with a chart listing the capacities through the complete
range of micrometer settings at the boiler pressure. Valves shall conform
to ASME BPVC SEC I. Blowoff valves in tandem shall be provided at each
point of blowdown as recommended by the boiler manufacturer. Piping shall
be extra-heavy weight, minimum, steel pipe conforming to ASTM A 106/A 106M
Grade B. Slow opening valves shall be balanced, seatless type unless
otherwise approved. Both surface and bottom blowdown connection points
with required accessories shall be provided. Valves shall have a capacity
equal to the capacity of the boiler and shall have forged steel bodies with
socket weld connections. Valve shall have a solid Stellite disk with
stainless steel seat sleeves. The bodies shall be designed for a minimum
working pressure of 2.07 MPa 300 psig. Quick opening valves shall be lever
operated, flat seat sliding disks with sealing bushing on the inlet side,
and shall be double tightening on both sides of the disk. Quick opening
valves shall be gear operated. All blowoff valves shall be suitable for
safe blowdown through the piping system installed. All pipe, valves, and
fittings shall be supplied as necessary to allow tie-in to a central point
for surface and bottom blowdown.
2.3.1.5
Safety Valves
Safety valves of proper size and of the required number and construction
and set pressures shall be in accordance with ASME BPVC SEC I and shall be
installed so that the exhaust steam will discharge through pipes extending
through the roof. Each exhaust riser shall have a drip-pan elbow to
prevent the accumulation of water on the valve. A suitable slip joint
shall be provided between the drip-pan elbow and the riser. Each exhaust
head shall be one-piece construction of plate steel, semisteel, or cast
iron, equipped with suitable baffle arrangement and drain connection for
removing entrained condensate and oil. Flow area through the valve shall
be larger than through the connecting pipe. Valves shall be set to
discharge at 10 percent above the operating pressure of the system.
2.3.1.6
Steam Nonreturn Valves
Steam nonreturn valves of size and pressure rating shown shall be installed
in the steam supply line from each boiler. Valves shall be arranged to
close automatically when there is a pressure differential of 35 kPa 5 psi
between the boilers and steam headers, and shall be arranged to operate as
stop valves. Valves shall be set with stem up, either inclined or
vertical, and shall be of the rising stem type. Valves shall be of the
SECTION 15846A
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