a.
Contracting Officer reserves the right to require the Contractor
to provide re-examination and recertification of welders.
b.
Radiographic testing of circumferential butt welded joints of pipe
with operating temperature of 177 degrees C 350 degrees F and
above shall be required on ten percent of the joints, the location
of which will be determined by the Contracting Officer; when more
than ten percent of the radiographically tested joints show
unacceptable defects radiographically test every joint of this
type piping.
c.
Equipment and Protection: Items of equipment for welding shall be
so designed and manufactured, and shall be in such condition as to
enable qualified operators to follow procedures and to attain
results specified. Protect welders and gas cutters from the light
of the arc and flame by approved goggles, shields, helmets, and
gloves. Replace cover glasses in helmets and shields when they
become sufficiently marred to impair the operator's vision. Take
care to avoid risk of explosion and fire when welding and gas
cutting near explosive or flammable materials. Ventilate welding
and gas cutting operations in accordance with paragraph 1910.252
(f) of 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
welder and work are protected properly. At temperatures between 0
degrees C and minus 18 degrees C 32 degrees F and 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 pipe of sand, mill scale and other
foreign material. After erection but before making final connections to
apparatus, thoroughly clean interior of piping. Flush piping with water
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 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.
SECTION 15501N
Page 151
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