Page 404 - Trenchless Technology Piping Installation and Inspection

354 Cha pte r Ei g h t

Pipe Quality
1. All pipes must be free of visible cracks, holes, foreign material,
foreign inclusions, blisters, or other deleterious 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. However, a
defective area of the pipe may be cut out and the joint fused
in accordance with the procedures stated above.
2. 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

8.7.3 Construction
Minimum Allowable Depths
Pipe-replacement systems follow closely the existing alignment and
grade of the host pipe. Therefore the installation depth is relatively
the same as the host pipe. However, if the replacement pipe diameter
is larger than the host pipe diameter, the effective cover above the
replacement pipe must be calculated as an increase of 10 in. for every
inch of increased diameter.
Equipment
The contractor must utilize pipe-replacement equipment with ade-
quate pulling/pushing force to complete pulls. The contractor must
verify the pulling/pushing force exerted on the pipe does not exceed
the manufacturer’s recommendation for allowable pulling force to
prevent damage to the pipe.
Method
1. Pipe must be assembled and fused on the ground in sections
equivalent to the length of the anticipated pull.
2. During installation, all bending and loading of the pipe must
be in conformance with the manufacturers recommendations
and must not damage the pipe.
3. Manholes must be prepared to ease the pipe-installation proc-
ess along the alignment and grade indicated on the plans.