TABLE OF CONTENTS Polyethylene used to manufacture pipe is available in several types and grades per ASTM D 1248. Some grades of polyethylene may crack or craze when subjected to certain levels of stress or when in contact with certain chemicals. This degradation is usually accelerated when high stresses and certain chemicals act simultaneously. This phenomenon is known as environmental stress cracking. Certain grades are highly resistant to stress cracking. Type III, class C, category 5, grade P34 polyethylene is a high-density, weather-resistant, stress-crack-resistant material (Table 7.16).
| Hydrostatic-design basis (HDB) | 1250 lb/in 2 |
| Hydrostatic-design stress (HDS) | 625 lb/in 2 |
| Elastic modulus | 100,000 lb/in 2 |
| Tensile stress (short-time) | 3200 lb/in 2 |
| Hazen- Williams coefficient C | 150 |
| Manning's coefficient n | 0.009 |
Polyethylene pipes are available in various sizes and wall configurations for varied applications, some of which are listed in Table 7.17. Other sizes for specific applications may be available from a particular manufacturer. See Table 7.18 for polyethylene standards.
| Application | Type | Size range, in |
|---|---|---|
| Industrial (includes gas) | Solid wall | 48 |
| Water (new service) | Solid wall | 3 |
| Water (insertion) | Solid wall | 4 |
| Gravity sewer (lining) | Solid wall | 4 48 |
| Gravity sewer | Profile (ribbed) wall | 18 96 |
| ASTM D 3287 | Biaxially Oriented Polyethylene (PEO) Plastic Pipe (SDR-PR) Based on Controlled Outside Diameter |
| ASTM D 3261 | Butt Heat Fusion Polyethylene (PE) Plastic Fittings for Polyethylene Plastic Pipe and Tubing |
| ASTM D 405 | Corrugated Polyethylene Tubing and Fittings |
| ASTM D 3197 | Insert-type Polyethylene... |
