terminal connections, blow out complete system with compressed air at 690
kPa (gage) 100 psig or more. Cleaning and cleanness of medium pressure
systems over 1724 kPa (gage) 250 psig and high pressure systems shall
conform to the paragraph entitled "Cleaning and Cleanness Requirements."
3.1.3.4
Changes in Pipe Size
Use reducing fittings for changes in pipe size. The use of bushings will
not be permitted. In horizontal lines, 65 mm 2 1/2 inches and larger,
reducing fittings shall be of the eccentric type to maintain the bottom of
the lines in the same plane.
3.1.3.5
Drainage and Flexibility
Compressed air piping shall be free of unnecessary pockets and pitched
approximately one mm per 400 mm 3 inches per 100 feet in the direction of
flow to low points. Where pipes must be sloped so that condensate flows in
opposite direction to air flow, slope one mm per 200 mm 6 inches per 100
feet or greater. Provide flexibility by use of fittings, loops, and
offsets in piping. Install branches at top of a main to prevent carryover
of condensate and foreign matter.
3.1.4
Threaded Joints
Where possible use pipe with factory cut threads, otherwise cut pipe ends
square, remove fins and burrs, and cut taper pipe threads in accordance
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 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
Flanged Joints in High Pressure System
Install using calibrated torque wrenches or feeler gage methods to assure
proper gasket compression. Calibrate torque wrench immediately prior to
use.
3.1.6
Welding and Brazing
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. Mark
welding and brazing detail drawings to identify the welder or brazer making
the joint.
3.1.6.1
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. Conform to paragraph
entitled "Cleaning and Cleanness Requirements" [for medium pressure systems
over 1724 kPa (gage) 250 psig] [and] [for high pressure] systems.
SECTION 15212N
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