HDPE Dual Wall
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1.01 SCOPE OF WORK
The contractor shall install a high density polyethylene
(HDPE) dual containment pipe system as shown on the
drawings. The contractor is responsible for installation and
testing of a complete and operational piping system.
The pipe system shall be designed for the following
conditions: The carrier and containment pipes shall have a
rated operating pressure requirement of ? psi and a minimum
burial depth of ? feet and a maximum burial depth of ? feet
(depending on the application).
The pipe system supplier shall have at least 5 year
experience in supplying pre-assembled dual containment
piping systems and materials as manufactured by Plastic
Fusion Fabricators, Huntsville, AL, (256) 852-0378.
following publications listed form a part of this specification
to the extent
referenced. References to
publications in the text are by basic designation
American Society for Testing and Materials (ASTM)
a. ASTM D-638, Tensile Properties
b. ASTM D-1238, Flow Rates of Thermal Plastics
c. ASTM F-1248, Environmental Stress
Crack Resistance (ESCR)
D-1505, Density of Plastics by Gradient Technique
e. ASTM D-2837, Hydrostatic Design
Basis for Thermal Plastics
ASTM D-3261, Butt Heat Fusion for Polyethylene (PE)
g. ASTM D-3350, Specs for
Polyethylene Pipe and Fittings
ASTM F-714 - 95, Polyethylene Plastic Pipe (SDR-PR)
Based on outside diameter
D-2321, Underground Installation of Flexible
Thermoplastic Sewer Pipe
a. ASME B32.8, Hydrostatic Testing Guidelines
b. Plastic Piping Institute Best
Practices TR 31/9-79
Contractor shall submit the following:
a. Documentation of the pipe system supplier's
experience with pre-assembled dual containment piping
b. Detailed fabrication drawings of all fittings
and special structures.
c. Pressure test results: Contractor shall submit
report (s) summarizing the results of pressure testing.
These report (s) shall list the sections of pipe tested,
the test pressure at the beginning and end of the test,
the ambient air temperature, and results of a visual
2.01 PIPE AND FITTINGS
used to fabricate the system supplied under this specification
be high density, extra high
molecular weight polyethylene pipe. The pipe
and fittings shall conform to ASTM D-3350 with a minimum
classification value of 345434C.
The pipe and fittings shall be made from the
same polyethylene resin base which meets this
a. Density - ASTM D-1505
Melt Index - ASTM D-1238
Modulus - ASTM D-790
Strength at Yield - ASTM D-638
ESCR - Environmental Stress Crack Resistance - ASTM
f. Hydrostatic Design
Basis - ASTM D-2837
g. ESCR -
Compressed Ring - ASTM F-1248
Cell Classification - ASTM D-3350; PE 345434C
2.02 DUAL CONTAINMENT PIPE SYSTEM
The dual containment pipe system shall consist of
pre-assembled HDPE carrier and containment pipe,
centralizers, and fittings.
Pipe supplied under this specification shall have IPS (Iron
Pipe Size) outside diameter (OD) and shall meet ASTM D-3035.
All pipe and fittings shall meet the pressure requirements
of the system as specified and in ASTM D-2837, hydrostatic
design basis for thermoplastic pipes.
Fittings shall be manufactured to the same pressure rating
and OD as the pipe.
a. All molded fittings shall be manufactured per
b. Pipe joints and fittings shall be supplied to
the job site ready for simultaneous butt fusion. The
fabricator shall show that the materials are capable of
butt fusion and shall provide a procedure to
consistently produce sound welds.
Centralizers welded to the carrier pipe shall support the
carrier pipe within the containment pipe. Centralizer
support spacing and other pipe system requirements shall be
in accordance with the drawings.
a. The centralizers shall be machined from pipe
grade resin sheet stock HDPE. Centralizers should be
placed in the pipe system such that the openings are
positioned as shown in the drawings.
End termination fittings shall be used to seal the system at
the ends. The fitting shall be simultaneously butt fused to
the carrier and containment pipe to seal the annular space.
No other closure or termination will be allowed. This
fitting will also provide transition to single wall piping.
Tie-ins to other piping systems and/or equipment, where butt
fusion is not applicable, shall be with HDPE flange-adapters
unless otherwise specified in the drawings. Mechanical or
clamp type fittings are not allowed under this
3.01 PIPE SYSTEM LAYOUT
Contractor shall verify the locations of all potentially
conflicting utilities and structures as indicated on the
Dual containment pipe and fittings shall be pre-assembled
prior to shipment to the job site. Pre-assembly shall
consist, at a minimum, of placement of the carrier pipe
within the containment pipe with all required centralizers
Pipe shall be stored on a clean, level, dry ground. If the
pipe must be stacked for storage, such stacking should be
done in accordance with the pipe supplierÕs
recommendations. The handling of the pipe should be done in
such a manner that the pipe is not damaged by dragging over
sharp objects or cut by lifting equipment.
Segments of pipe having cuts or gouges in excess of 20% of
the wall thickness, shall not be incorporated into the
Sections of HDPE dual containment pipe shall be joined into
continuous lengths on the job site
following the guidelines of ASTM D-2657, using the
simultaneous butt fusion method of joining the
The pipe system supplier shall provide and approve all
equipment used for the pipe
system. The butt fusion equipment used to join the pipe and
fittings shall be manufactured by McElroy Manufacturing,
Tulsa, OK; and come equipped with the McElroy
Dataloggerª, capable of quality assurance documentation
for pipe fusion parameters such as the time, temperature,
and pressure for each fusion made.
Fused segments of pipe shall be handled with the pipe system
supplier's recommendations. Bending of the pipe during
installation shall be limited and shall not exceed the pipe
system supplier's recommendations.
All buried pipe shall be installed in accordance with ASTM
D-2321, Underground installation of flexible thermoplastic
carrier and containment pipe shall be subjected to both a
and a visual test. Testing
shall be the responsibility of the contractor. The test
may be witnessed by the owner. The owner
shall be notified at least 3 days in
advance of such tests. The final test report shall be
delivered to the owner
and, the pipe
supplier, within 30 days of the test.
Pressure Test: After the pipe has been installed, fusion
completed, and the trench partially backfilled (leaving the
joints exposed for examination), the carrier pipe shall be
filled with water in a manner to expel all air. The pipeline
shall be subjected to a test pressure of 1.5 times the
systems operating pressure for a period of a least 1 hour.
The test time should not exceed 3 hours. Add and measure the
amount of make up water required to return to the test
pressure and compare this with the maximum allowances stated
in Underground Installation of Polyolefin Piping as
published by the Plastics Pipe Institute.
Containment Pipe Testing: The carrier pipe shall be brought
up to and held at the system test pressure while the
containment pipe is leak tested. Based on the lowest
pressure rated fitting or component in the system, air
pressure of no higher than 3 psi shall be used. Extreme
caution should be used to insure that the annular space is
not over pressurized. Air is a compressible gas and is very
dangerous. Always build and release pressure slowly. The
test period shall be limited to 10 minutes. The pipe shall
be brought up to test pressure and held for 10 minutes or
until the pressure stabilizes. The test shall begin when the
pressure stabilizes and lasts for ? minutes. If no
significant pressure drop is noted, the pipe has passed the
Retesting: If any deficiencies are revealed during the test,
such deficiencies shall be corrected. The tests shall be
reconducted until the results of the tests are within
specified allowances with no additional cost to the owner.
Visual Test: All exposed joints, fittings, and valves shall
be examined for leaks. Visible leaks shall be stopped and/or
the defective pipe, fitting, joint, or valve shall be
completion of the installation of the HDPE piping system, all
surplus materials resulting
from the work shall be removed form the site and
disposed of by the contractor.
END OF SECTION
NOTE: All ? blanks are to be filled based on the application
and the SDR Rating (or system pressure) of the pipe.
HDPE Pipe & Fittings
Typical Physical Properties
ASTM Test Method
|Flow Rate (190/21.6)
|Tensile Strength @ Ultimate
|Tensile Strength @ Yield
|Flexural Modulus 2% Secant
|Environmental Stress Crack Resistance (ESCR) Fo, Cond.
||Type III Category
|PPI Hydrostatic Design Basis:
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