HDPE Geothermal Piping Technical Data

Recommended Butt and Socket Fusion Procedures for HDPE Pipe  View Instructions (PDF Format)

Table 1   Approximate Water Volume for 100 Feet of Pipe

Nominal Pipe Size	Gallons	Nominal Pipe Size	Gallons
¾” IPS SDR 11	2.93	3” IPS SDR 11	32.57
1” IPS SDR 11	4.60	4” IPS SDR 11	53.84
1 ¼” IPS SDR 11	7.33	6” IPS SDR 15.5	133.47
1 ½” IPS SDR 11	9.60	8” IPS SDR 15.5	226.17
2” IPS SDR 11	15.00
Approximate volume of water in U.S. gallons at 73 degrees (F) for ASTM D 3035 nominal outside diameter and average wall thickness for pipe.

Geothermal Piping Technical DATA

 

Table  

Table 2   Pressure Rating (psi) vs. Temperature (F)

Temperature (F)	SDR 15.5	SDR 11	SDR 9
73	110	160	200
80	104	151	189
90	95	138	173
100	87	126	157
110	78	114	142
120	70	102	128
130	63	91	114
140	55	80	100
Pressure ratings for water.  PE3408 HDPE-1600 psi at 73 degrees (F) and 800 psi at 140 degrees (F).  Intermediate pressure vs. temperature ranges interpolated in accordance with PPI TN18.

 

HDPE Pipe Heat Transfer

Material	K-Value, BTU-h/ft-degree (F)
HDPE PE3408 Pipe	0.225
PVC Pipe	0.087
Heat transfer properties of various materials can be expressed by a “K-value”.  A higher K-value reflects greater heat transfer properties.

 

Specifications for HDPE Geothermal Pipe and Fittings

All pipe and fittings are manufactured from high density, high molecular weight, PE3408 polyethylene resin, which meets or exceeds ASTM D 3350 cell classification 345464C, and is listed by the Plastic Pipe Institute in PPI TR-4 with HDB ratings of 1600 psi at 73 degrees F and 800 psi at 140 degrees F. All pipe is manufactured in accordance with ASTM D 3035.  Molded Fittings are manufactured in accordance with ASTM D 3261 (butt outlet), and ASTM D2683 (socket outlet).  Electrofusion fittings shall be manufactured in accordance with ASTM F-1055 and mechanical fittings in accordance with ASTM D-1924, Section 3.1.6.1. 

Clean rework material from the manufacturer’s own production may be used provided the pipe or fittings meet all requirements of this specification.  Recycled and reclaimed material from outside the manufacturer’s plant shall not be used.  Pipe used for vertical bore applications shall include a factory fused molded U-bend fitting. 

Approved joining methods are heat fusion, electrofusion, flanging, transition fittings, and approved mechanical stab fittings.  Persons performing heat fusion shall be qualified in accordance with the manufacturer’s recommended fusion joining procedures.  Electrofusion and mechanical joints shall be made in accordance with the fitting manufacturer’s instructions. 

General Guidelines for Geothermal HDPE Piping Systems

-         Verify that the total system pressure, operating plus surge, does not exceed the pressure rating of the lowest rated component in the system. 

-         Carefully inspect the pipe to detect any damage that may have occurred during shipping or handling. 

-         Conduct hydrostatic leak testing in accordance with manufacturer’s procedures.  Do not test the pipe system with pressurized air. 

-         Install HDPE geothermal piping in accordance with accepted standards for water-source heat pump applications and ASTM D2774 (Underground Installation of Thermoplastic Pressure Piping) 

-         When laid in a trench, ensure that the trench bottom is smooth and free from sharp or angular objects.  Embedment soils must be free from refuse, organic material, cobble, boulders, large rocks or stones, and frozen clods.  Blocking must not be used to change pipe grade or to intermittently support pipe across the excavated section. 

-         When installed down hole, such as in a vertical loop, be sure any ballast used to facilitate downhole insertion does not impinge, gouge, or cut into the pipe.