cutting near explosive or flammable materials. Ventilate welding
and gas cutting operations in accordance with paragraph 29 CFR
1910-SUBPART Q.
d.
Surface Conditions: Do not weld when atmospheric temperature is
less than minus 18 degrees C zero degrees F, when surfaces are
wet, when rain or snow is falling or moisture is condensing on
surfaces to be welded, nor during periods of high wind, unless the
welder and work are protected properly. At temperatures between
zero degrees C 32 degrees F and minus 18 degrees C zero degrees F
heat with a torch the surface for an area within 80 mm 3 inches of
the joint to be welded to a temperature warm to the hand before
welding. Free surfaces to be welded from loose scale, slag, rust,
paint, oil, and other foreign material. Joint surfaces shall be
smooth, uniform and free from fins, tears, and other defects which
might affect proper welding. Remove slag from flame-cut edges to
be welded by grinding, but temper color need not be removed.
Thoroughly clean each layer of weld metal by wire brushing prior
to inspection or deposition of additional weld metal.
3.1.2.10
Cleaning of Piping
Before installing pipe, thoroughly clean it of sand, mill scale and other
foreign material. After erection but before final connections are made to
apparatus thoroughly clean the interior of piping. Flush with water piping
except air and fuel lines, in addition, blow out steam lines with
intermittent high pressure steam blows to promote shedding of internal
scale. Blow compressed air and fuel oil lines clean with 552 to 690 kPa
(gage) 80 to 100 psig air dried to a 2 degrees C 35 degree Fdew point at
552 kPa (gage) 80 psig. Sterilize potable water piping by means of liquid
chlorine or hypochlorite in accordance with AWWA C651 before placing water
system in service. Take care during fabrication and installation, to keep
piping, valves, fittings and specialties free of loose welding metal chips
of metal or slag, welding rods and other foreign matter. Blowing or
flushing shall in no case be channeled through equipment, pump, control
valve, regulating valve, instrument gage or specialty in the system.
Provide temporary screens, strainers, connections, spool pieces and
bypasses consisting of piping or hoses, pumps and other required equipment
temporarily installed for the purpose of cleaning and flushing piping.
Drain flushing water and test water to the sanitary sewer system.
3.1.2.11
Reduction in Pipe Size
Provide reducing fittings for changes in pipe size; the use of bushings
will not be permitted. In horizontal steam lines, reducing fittings shall
be the eccentric type to maintain the bottom of the lines in the same
plane. In horizontal water mains, reducers shall be set to maintain the
top of the lines in the same plane.
3.1.2.12
Expansion Control
Provide bends, loops, and offsets wherever practical to relieve
overstressed piping systems due to thermal expansion and to provide
adequate flexibility. Cold spring piping system as indicated but not more
than 50 percent of the total linear expansion.
3.1.2.13
Connection to Equipment
Provide unions or flanges where necessary to permit easy disconnection of
SECTION 15511N
Page 82
Previous Page
