Page 402 - Trenchless Technology Piping Installation and Inspection

352 Cha pte r Ei g h t

4. Pipe must have square and machine-beveled ends. The pipe
end maximum out-of-square tolerance must be 0.04 in.
(measured across the diameter).
5. The maximum allowable straightness deviation over any 10-ft
length of steel pipe is 0.125 in. Likewise, ductile iron, and
PVC pipe must have similar straightness tolerances. HDPE
pipe does not to be straight.
6. Pipe must be without any significant dimensional or surface
deformities. All pipes must be free of visible cracks, holes,
foreign material, foreign inclusions, blisters, or other deleteri-
ous or injurious faults or defects. Any section of the pipe with
a gash, blister, abrasion, nick, scar, or other deleterious fault
greater in depth than 10 percent of the wall thickness, must
not be used and must be immediately removed from the
site.
7. Any of the following defects warrants pipe rejection:
• Concentrated ridges, discoloration, excessive spot rough-
ness, and pitting
• Insufficient or variable wall thickness
• Pipe damage from bending, crushing, stretching, or other
stress
• Pipe damage that impacts the pipe strength, the intended
use, the internal diameter of the pipe, and internal rough-
ness characteristics
• Any other defect of manufacturing or handling

Host Pipe
1. Most brittle pipe materials make good candidates of host
pipes for pipe bursting. Ductile pipe must be scored and then
split as in the pipe-splitting operations described above.
2. Pipe made of nonductile abrasive material, but with ductile
reinforcing, is the most difficult to replace using most pipe-
replacement techniques.
3. Clay and cast-iron pipe are good candidates for pipe burst-
ing. If PVC joints exist on clay pipe, or if ductile repair clamps,
service saddles, and fittings exist on cast-iron pipe special
application tools must be used in pipe bursting. Sacrificial
external sleeve pipes must be used to ensure protection for
plastic replacement pipes for high-pressure pipe applications
against sharp fragments of host pipe.
4. Plain concrete pipe is a good candidate for pipe bursting.
However, thick plain concrete pipe, reinforced encasements,
or repair areas in the pipe need special considerations.