Sub-Head
NIBCO INC. WORLD HEADQUARTERS • 1516 MIDDLEBURY ST. • ELKHART, IN 46516-4740 • USA • PH: 1.800.234.0227
TECH SERVICES PH: 1.888.446.4226 • FAX: 1.888.336.4226 • INTERNATIONAL OFFICE PH: +1.574.295.3327 • FAX: +1.574.295.3455
www.nibco.com
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A H E A D O F T H E F L O W
®
Material Selection
Polyethylene (PE)
Polyethylene is the most common olefin material and is typically
used in transporting water. Because olefins cannot be joined
with cements, barbed insert fittings are used for mechanical
assembly. PE is light weight, low cost, has excellent chemical
resistance, low coefficient of friction, and is non-toxic.
Plastic Piping Standards
Many commercial, industrial, and governmental standards or specifications are available to assist the design engineer in specifying
plastic piping systems. Standards most frequently specified in plastic piping systems are American Society for Testing and Materials
(ASTM) Standards. Below is a list and description of those standards most typically applied to industrial plastic piping.
Polyphenylsulfone (PPSU)
Polyphenylsulfone is a thermoplastic that is tough, rigid, high-
strength, and retains its properties between -148° F and 302° F
(-100° C and 150° C). PPSU has very high dimensional stability;
the size change when exposed to boiling water or 302° F (150° C)
air generally falls below 0.1 percent. Polyphenylsulfone is highly
resistant to mineral acids, alkali, and electrolytes, in pH ranging
from 2 to 13. PPSU is resistant to oxidizing agents; therefore,
can be cleaned by bleaches. Also, PPSU is resistant to surfac-
tants and hydrocarbon oils. However, PPSU is not resistant to
low-polar organic solvents (e.g., ketones and chlorinated hydro-
carbons) and aromatic hydrocarbons. In addition, PPSU is often
chosen for difficult applications including high water tempera-
tures, chlorides, or when water quality may increase the risk of
dezincification, a type of corrosion that can adversely affect
metal fittings.
Brass
Brass is the term used for copper alloys where zinc is the prin-
ciple alloying element along with copper. Brass has a yellow
color, somewhat similar to gold. Brass plumbing components
may be machined from extruded shapes, forged, or cast. This
alloy is mainly used for decorative fixtures, plumbing compo-
nents, and electrical applications. Today, almost 90% of all
brass alloys are recycled.
Copper (Cu)
Copper (Cu) is a natural element that has historically been the
dominant material used in plumbing, heating, cooling, and other
piping applications. Copper is a ductile metal with excellent
thermal conductivity and is corrosion resistant. The materials
used in copper piping products comply with the requirements of
specifications established by the American Society for Testing
and Materials (ASTM). The alloy customarily used for copper
tube and copper fittings is designated as C12200 (Copper No.
122). This alloy contains a minimum of 99.9% pure copper and
is deoxidized by the addition of phosphorus. Other copper alloys
may be used.
Cross-Linked Polyethylene (PEX)
PEX is the common name for cross-linked polyethylene. PEX
tubing is predominantly used in water distribution systems,
hydronic radiant heating systems, and natural gas systems.
Almost all PEX is made from high density polyethylene (HDPE).
PEX contains cross-linked bonds that are introduced into the
polymer structure, changing the thermoplastic into a thermoset.
Cross-linking is accomplished during or after the extrusion of the
tubing. The required degree of cross-linking, according to ASTM
F876, is between 65 to 89 percent.
The cross-linking process improves high-temperature mechani-
cal properties, low-temperature impact, tensile strength, resis-
tance to brittle fracture, and scratch resistance properties.
Cross-linking may be done by the peroxide (Engel) method,
silane method, or electron beam method. NIBCO
®
PEX is
produced by the electron beam method. This is the cleanest
and most environmentally friendly of the three methods. Also
this method does not involve other chemicals and uses only
high-energy electrons to split the carbon-hydrogen bonds and
facilitate cross-linking.
