Page 71 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

PIPING

PIPING 2.21

generally uses push-on gaskets for jointing. PVC pipe is self-extinguishing and will not
burn. However, when subject to conditions of a fire, a toxic gas is emitted.
Pipe used for exterior water mains may be required to have special approval if used to
supply fire protection water.
PVC pipe should conform to the following ASTM standards:
1. D-2241, D-1785, and D-272: interior water pipe pressure. Fittings shall conform to
D-2665
2. Pipe used for exterior water mains shall conform to AWWA standards
3. D-2665, D-3034, F-679, and F-769: drainage pipe and fittings
4. CS 272: PVC plastic DWV pipe and fittings

Chlorinated Polyvinyl Chloride (CPVC)
CPVC is a chemical modification of PVC, with an extra chlorine atom in its structure
that extends its service temperature limitations to about 200°F, 50°F more than PVC pipe.
Available sizes and other properties are very similar.
CPVC pipe should conform to the following ASTM standards: ASTM D-2846, F-441,
and F-442 for piping and F-437, F-438, and F-439 for fittings.

Polypropylene (PP)
PP is a polyolefin available in two types, type 1, homopolymer, and type 2, copolymer. It
has superior resistance to sulfur-bearing compounds and is capable of withstanding a wide
range of both corrosive and sanitary effluents. It is the most resistant to organic solvents of
all the common plastic pipe materials, and is only slightly less rigid than PVC. Its principal
use is for laboratory drainage purposes. It is superior to PE at higher temperatures. When
manufactured with no pigment, it is widely used for pure water system distribution.
PP is available in schedule 40 and 80 and in diameters up to 12 in (300 mm). Jointing
methods include solvent-welded socket joints, heat-fused socket-welded joints, heat-fused
butt-welded joints, threaded joints, or proprietary mechanically threaded joints. Only
schedule 80 can be threaded.
PP pipe and fittings shall conform to ASTM F 2389 and CSA B-137.11. Some joints
refer to D2657 for heat-fused socket joints and ASTM 2.1 for threaded joints.

Polyethylene (PE)
PE is probably the best known polyolefin. It is widely used because of its superior tough-
ness, ductility, flexibility, and ability to dampen water shock. The upper service tempera-
ture limit is around 140°F. It is used for underground fuel gas distribution piping and site
irrigation systems and it has NSF approval for potable water piping. It is also used for all
types of gravity and pressure drainage applications within chemical and temperature limits
where flexibility is an advantage, particularly in foundation drains. It has the least mechani-
cal strength of all the common plastic pipe materials, and is only moderately resistant to
solvents.
There are four types of PE manufactured, rated by the density of the natural resin used,
types 1, 2, 3, and 4. Types 3 and 4 have the highest density and have been given the abbre-
viation HDPE. The most commonly used pipe is composed of types 3 and 4. It is available
in schedule 80 in diameters up to 6 in (150 mm). It is joined by socket and butt heat-fusion
and insert fittings for water irrigation systems.

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