with ASME B1.20.1. Threads shall be smooth, clean, and full cut. Apply
thread tape to male threads only. Work piping into place without springing
or forcing. Backing off to permit alignment of threaded joints will not be
permitted. Engage threads so that not more than three threads remain
exposed.
3.1.5
Welding and Brazing Procedures
Perform welding and brazing in accordance with qualified procedures using
qualified welders and welding operators and brazers. Do not perform
welding and brazing when the quality of the completed weld or braze could
be impaired by the prevailing working or weather conditions. The
Contracting Officer will determine when weather or working conditions are
unsuitable for welding. Welding of hangers, supports, and plates to
structural members shall be in accordance with AWS D1.1/D1.1M.
3.1.5.1
Cleaning for Welding and Brazing
Surfaces to be welded or brazed shall be free from loose scale, slag, rust,
paint, oil, and other foreign material. Joint surfaces shall be smooth and
free from defects which might affect proper welding. Clean each layer of
weld metal thoroughly by wire brushing, grinding, or chipping prior to
inspection or deposition of additional weld metal.
3.1.5.2
Stress Cracking During Brazing
For material susceptible to stress corrosion cracking from molten brazing
filler metal, avoid applying stress during brazing.
3.1.5.3
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.
3.1.6
Flare Fittings
Provide flare fittings only where necessary to connect copper tubing to
equipment. Use short sections of annealed tubing soldered or brazed to
hard drawn tubing using couplings on expanded ends on the annealed tubing
made with special tools designed for that purpose. Make flares with the
appropriate flaring tools. Cut annealed tubing only with cutting wheel
tool. Do not ream out inside burr or lip left by the cutting wheel but
fold back lip with flare tool to form seal/gasket inside flare. When new,
the flare should cover not more than 75 percent of the flare seating
surface of either the male or female flare fittings. Put the flare nut on
the tube before making the flare.
3.1.7
Valves
ASME B31.1. Install valves at the locations indicated and elsewhere as
required for the proper functioning of the system.
3.1.7.1
Provide gate valves unless otherwise directed. Install valves in positions
accessible for operation and repair. Install valve with stem horizontal or
above.
SECTION 15211N
Page 27
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