Page 55 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

PIPING

PIPING 2.5

TABLE 2.2 Aluminum Alloys

Alloy number UNS number series Major alloying elements
1XXX A91NNN Aluminum with 99.00% minimum purity
2XXX A92NNN Copper
3XXX A93NNN Manganese
4XXX A94NNN Silicon
5XXX A95NNN Magnesium
6XXX A96NNN Magnesium plus silicon
7XXX A97NNN Zinc
8XXX A98NNN Miscellaneous

known as yellow brass. When used for drainage systems, it is obtained plain end. Joints for
this pipe can be either threaded, flanged, brazed, or soldered. Brass pipe for utility piping
systems shall conform to ASTM B 43: Red Brass Tube, Seamless.
Brass is generally used for local branch drainage lines, where this alloy will resist specific
corrosive drainage effluent and, in larger sizes, for potable and other water supply lines and
to match existing work for alterations. Its advantages and disadvantages are the same as for
copper.
Brass castings for pipe fittings and components of plumbing fixtures are not made with
the same alloy as pipe and often contain lead. Pipe is lead free and brass fittings with lead
are no longer permitted by code to be used for potable water.

CAST IRON SOIL PIPE (CI)

Technically known as gray cast iron, this pipe is a ferrous material alloyed with carbon in
the form of free graphite flakes, silicon, and other impurities. It is available in three clas-
sifications: service (standard) weight, extra heavy, and hubless. The pipe is commonly lined
internally with cement or coal tar enamel, and coated externally with a variety of materials
to reduce corrosion by soils.
Joints require two types of pipe ends: hub and spigot or hubless. The hub and spigot
ends can be joined either by caulking or by the use of an elastomeric compression gasket.
Hubless pipe is joined by an external compression coupling.
Cast iron soil pipe should conform to the following standards:
1. ASTM A 74: Hub and Spigot Cast Iron Soil Pipe and Fittings
2. CISPI 301: Hubless Cast Iron Soil Pipe
3. CISPI 310: Hubless Cast Iron Fittings for Soil Pipe
Cast iron is well suited for sanitary effluent and can be used in any part of a gravity
drainage and vent system. Advantages include an ability to withstand moderate external
pressure (such as direct burial in soil), good fire resistance, good flow characteristics, and
good corrosion resistance in most natural soils. Piping in use for over 100 years has been
documented. Disadvantages are that the pipe is brittle and subject to breakage when roughly
handled, it is subject to corrosive attack by aggressive soils and highly septic effluent, it is
heavy, and it has a high initial material cost.
Cast iron pipe is manufactured with both inside and outside coated for corrosion resis-
tance. A PE wrapping is often used to eliminate external corrosion of cast iron pipe buried
underground on a site.

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