HDPE Dual Wall Containment Pipe
Sample Specification

Click here for Typical Physical Properties

1.0 GENERAL

1.01 SCOPE OF WORK

1. 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.

2. 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).

3. 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.

1.02 REFERENCES

The following publications listed form a part of this specification to the extent
referenced. References to publications in the text are by basic designation
only.

1. 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. ASTM D-1505, Density of Plastics by Gradient Technique
e. ASTM D-2837, Hydrostatic Design Basis for Thermal Plastics
f. ASTM D-3261, Butt Heat Fusion for Polyethylene (PE)
g. ASTM D-3350, Specs for Polyethylene Pipe and Fittings
h. ASTM F-714 - 95, Polyethylene Plastic Pipe (SDR-PR) Based on outside diameter
i. ASTM D-2321, Underground Installation of Flexible Thermoplastic Sewer Pipe

2. Other Publications

a. ASME B32.8, Hydrostatic Testing Guidelines
b. Plastic Piping Institute Best Practices TR 31/9-79

1.03 SUBMITTALS

1. Contractor shall submit the following:

a. Documentation of the pipe system supplier's experience with pre-assembled dual containment piping systems.

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 test.

2.0 PRODUCTS

2.01 PIPE AND FITTINGS

The pipe used to fabricate the system supplied under this specification shall
be high density, extra high molecular weight polyethylene pipe. The pipe
and fittings shall conform to ASTM D-3350 with a minimum cell
classification value of 345434C. The pipe and fittings shall be made from the
same polyethylene resin base which meets this specification.

1. Physical Properties:

a. Density - ASTM D-1505
b. Melt Index - ASTM D-1238
c. Flex Modulus - ASTM D-790
d. Tensile Strength at Yield - ASTM D-638
e. ESCR - Environmental Stress Crack Resistance - ASTM D-1693
f. Hydrostatic Design Basis - ASTM D-2837
g. ESCR - Compressed Ring - ASTM F-1248
h. Cell Classification - ASTM D-3350; PE 345434C

2.02 DUAL CONTAINMENT PIPE SYSTEM

1. The dual containment pipe system shall consist of pre-assembled HDPE carrier and containment pipe, centralizers, and fittings.

2. Pipe supplied under this specification shall have IPS (Iron Pipe Size) outside diameter (OD) and shall meet ASTM D-3035.

3. 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.

4. Fittings shall be manufactured to the same pressure rating and OD as the pipe.

a. All molded fittings shall be manufactured per ASTM D-3261.

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.

5. 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.

6. 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.

7. 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 specification.

3.0 EXECUTION

3.01 PIPE SYSTEM LAYOUT

1. Contractor shall verify the locations of all potentially conflicting utilities and structures as indicated on the drawings.

3.02 PRE-ASSEMBLY

1. 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 in place.

3.03 STORAGE

1. 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.

2. Segments of pipe having cuts or gouges in excess of 20% of the wall thickness, shall not be incorporated into the system.

3.04 INSTALLATION

1. 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 pipe.

2. The pipe system supplier shall provide and approve all fusion
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.

3. 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.

4. All buried pipe shall be installed in accordance with ASTM D-2321, Underground installation of flexible thermoplastic sewer pipe.


3.05 HYDROSTATIC TESTS

The carrier and containment pipe shall be subjected to both a pressure test
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.

1. 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.

2. 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 test.

3. 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.

4. 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 replaced.


3.06 CLEANUP

Upon completion of the installation of the HDPE piping system, all debris and
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

Property

ASTM Test Method

SI Units

English Units

Density (Natural) D1505 0.946 g/cc --
Density (Black) D1505 0.957 g/cc --
Flow Rate (190/21.6) D1238 8.5 gm/10min. --
Tensile Strength @ Ultimate D638 34.5 MPa 5,000 psi
Tensile Strength @ Yield D638 24.1 MPa 3,500 psi
Ultimate Elongation D638 >800% >800%
Flexural Modulus 2% Secant D790 938 MPa 136,000 psi
Environmental Stress Crack Resistance (ESCR) Fo, Cond. C D1693 >10,000 hrs. >10,000 hrs.
Thermal Expansion   2x10-4 cm/cm/degrees C 1.1x10-4 in./in./degrees F
Cell Classification D3350 345434C Grade PE34
Material Classification: D1248 Type III Category 5 Class C
PPI Hydrostatic Design Basis: D2837    

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