Page 359 - Trenchless Technology Piping Installation and Inspection

Inspection and QA/QC for Trenchless Installation and Replacement Methods 309

3. Steel pipe must have a roundness tolerance, so that the differ-
ence between the major and minor outside diameters must
not exceed 1 percent of the specified nominal outside diame-
ter, or 0.25 in., whichever is less. Likewise, concrete pipe,
CCFRPM, and PCP must have a similar roundness tolerance.
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. Pipe must 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 delete-
rious 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

Pipe Joint Cushion
A cushioning material must be used between pipe segments to assist
in distributing the jacking loads evenly across the section of the pipe,
and to prevent chipping or breaking of the pipe ends due to concen-
trated pressure caused by any slight irregularity of the pipe ends.
The most common type of material used as a cushion material is
particleboard.

8.1.3 Construction

Minimum Allowable Depths
The recommended minimum depth of cover must be 6 ft or 2 times
outside diameter of the pipe. For slurry pipe jacking minimum depth
cover must be 6 ft or 3 times outside diameter of the pipe. In locations
where the road surface is superelevated, the minimum depth of the
bore must be measured from the lowest side of the pavement surface.
Conventional pipe jacking can work with least cover of all systems.