Page 72 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

PIPING

2.22 CHAPTER TWO

PE pipe should conform to the following ASTM standards:
1. D-2513: underground fuel gas pipe, D-2683 and D-2513: fittings
2. D-2239, D-2447, and CS-255: pressurized water piping
3. D-2609: fittings
4. D-3350: PE pipe material
5. HDPE PES-AL-HDPE
6. ASTM F 1986

Cross-Linked Polyethylene (PEX)
PEX is essentially a polyethylene which has undergone a chemical or physical reaction
that causes the molecules of the PE chains to link together. This creates a flexible, three-
dimensional structure between the molecular chains similar to a chain link fence. It is used
for plumbing and heating applications and has demonstrated excellent characteristics at
elevated temperatures.
There are several methods of manufacturing PEX tubing and all shall have ASTM and
NSF approval for potable water piping.
The three methods used for cross linking PEX tubing are the peroxide method, the irra-
diation method, and the silane method, in Europe referred to as PEX-b. It is recommended
that manufacturers test data for chlorine resistance be obtained.
PEX tubing shall conform to the following standards:

1. ASTM F 876
2. NSF Standards 14 and 61

Acrylonitrile Butadiene Styrene (ABS)
ABS is used for interior and exterior sanitary and industrial drainage and vent systems and
pressurized liquid lines such as those used for salt water, irrigation, crude oil, and pumped
waste. NSF has approved this material for potable water systems. It is slightly more rigid
than PVC and is the least resistant to solvents of all the popular plastic materials. The gener-
ally accepted upper service temperature limit is 175°F. ABS is available in schedule 40 and
80, and in diameters up to 12 in (300 mm). Drainage fittings are available only in diameters
up to 6 in (150 mm). Joints are made by solvent cement, threaded, or compression joints.
Only schedule 80 can be threaded.
ABS pipe should conform to the following ASTM standards:

1. D-2751 and F-628: sewer pipe and fittings
2. D-2661 and D-275 1: pressurized water pipe
3. ASTM D-2661: fittings

Polybutylene (PB)
PB is a polyolefin having slightly less stiffness than regular PE, but with a higher strength
than HDPE. It has good abrasion resistance, is resistant to creep, and retains its strength at
elevated temperatures. This material is resistant to soaps, most acids and bases, and polar
solvents at lower temperatures. It is attacked by some aromatic hydrocarbons and chlori-
nated solvents. PB pipe is used mainly for water and, to a lesser degree, for pressurized

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