3.1.6.2
Stress Cracking During Brazing
For austenitic stainless steel and other material susceptible to stress
corrosion cracking from molten brazing filler metal, avoid applying stress
during brazing.
3.1.6.3
Welding or Brazing of Valves
Welding or Brazing of Valves: Disassemble valves subject to damage from
heat during welding or brazing and reassemble after installation. Open
valves two or three turns off the seat when not subject to heat damage
during welding or brazing; do not backseat valve.
3.1.7
Valves
Install valves in conformance with ASME B31.1 at the locations indicated
and elsewhere as required for the proper functioning of the system.
3.1.7.1
Globe Valves
Install globe valves so that the pressure will be below the disk.
Install
globe valves with the stems vertical.
3.1.7.2
Pressure-Reducing Valves
Provide compressed air entering each pressure-reducing valve with a
strainer. Provide each pressure-reducing valve unit with two block valves
and with a globe or angle bypass valve and bypass pipe. Provide a bypass
around a reducing valve of reduced size to restrict its capacity to
approximately that of the reducing valve. Provide each pressure reducing
valve unit with an indicating gage to show the reduced pressure, and a
safety valve on the lower pressure side. These requirements do not apply
to small pressure regulating valves used to adjust pressure for pneumatic
equipment.
3.1.8
Hangers and Supports
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NOTE: See USACE TI 809-04 "Seismic Design for
Essential Buildings" (for new designs) or TI 809-05
"Seismic Design for Existing Buildings" (for
renovations), for calculating pipe support spacing
for schedules not shown. Also, space supports for
high pressure air piping to provide restraint
against whipping and damage to other piping if the
high pressure line breaks; see DM 3.5, "Compressed
Air and Vacuum Systems," Section 7, "Piping
Systems." Delete Table I and reference to seismic
requirements if not required.
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Selection, fabrication and installation of piping hangers and supports
shall conform to MSS SP-58, MSS SP-69, and MSS SP-89 [except that spacing
of the hangers and supports shall be as per Table I.] [Provide seismic
restraints for piping in accordance with SMACNA Seismic Restraint Mnl.]
SECTION 15212N
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