How to Guide

28
Cast Iron Installation
DESIGN AND ENGINEERING DATA
SUPPORT SPACING AND HANGERS
NOTE: The following information provides general
guidelines. It should be used only as a reference and not
as a guarantee of performance. Specific installation
instructions and techniques may be required as a result
of local plumbing and building codes, engineering
specifications and instructions.
Cast iron soil pipe installed in the horizontal position
shall be supported at every hub (hub and spigot) or every
coupling (hubless). The hanger shall be placed within 18”
of the hub or coupling. Joints used for connecting cast
iron soil pipe possess sufficient shear strength to require
one hanger per joint or hub.
Installations requiring multiple joints within a four-foot
developed length shall be supported at every other or
alternating hub or coupling.
Vertical components shall be secured at each stack base
and at sufficiently close intervals to keep the system in
alignment and to adequately support the pipe and its
contents. Riser clamps, sometimes called floor or friction
clamps, are required for vertical piping in multi-story
structures in order for each floor not to exceed 15 feet.
Support stacks at their bases and at sufficient floor
intervals to meet the requirements of local codes.
Approved metal clamps or hangers should be used
for this purpose.
• Horizontal Piping – Support horizontal pipe and
fittings at sufficiently close intervals to maintain
alignment and prevent sagging or grade reversal.
Support each length of pipe by an approved hanger
located not more than 18” from the joint. Support
terminal ends of all horizontal runs or branches
and each change of direction or alignment with an
approved hanger.
FIRE RESISTANCE OF CAST IRON
SYSTEMS
When it comes to fire-resistive construction and material
selection, cast iron soil pipe systems offer a piping
product that is non-combustible. Cast iron soil pipe and
fittings will not burn in the event of a building fire. Many
building codes require that newly constructed buildings
be built with fire compartments and separations; these
separations or compartments help reduce the spread of
fire and smoke within a building in the event of a fire. In
a fire-resistive constructed building, the compartments
may be penetrated with pipe or other service penetration.
Those penetrations must be sealed back to the original fire
integrity of the compartment with a material or product
that seals the annular space around the penetration to
stop the spread of flame and smoke.
Because cast iron soil pipe is considered a non-
combustible material, it is also a perfect choice to use
in return-air plenums for DWV applications.
Note: This manual is not a complete engineering
reference addressing all aspects of design and installation
of a drain, waste and vent or sanitary storm system.
Failure to properly support or hang cast iron pipe could
result in system failure and/or property damage.
• Vertical Piping – Secure vertical piping at sufficiently
close intervals to keep the pipe in alignment and to
support the weight of the pipe and its contents.
To help ensure adequate fire-resistance, always refer to the
fire-stop system manufacturer’s safety information and
recommendations.