Cast Iron Soil Pipe & Fittings Handbook
Chapter 2 - Installation of Cast Iron Soil Pipe and Fittings
Joining Methods for Cast Iron Soil Pipe
Compression Gaskets
There
are generally three methods used for joining cast iron soil pipe. Hub and
spigot cast iron soil pipe may be joined by the compression gasket or a
caulked joint. Hubless cast iron soil pipe are joined by using a hubless
coupling.
The
compression gasket is a precision molded one-piece gasket that is made
of an elastomer that meets the requirements of ASTM C-564. The physical
characteristics of this elastomer ensures that the gasket will not decay
or deteriorate from contact with the materials flowing in the pipe or chemicals
in the soil or air around the pipe. The compression joint is made as follows:
-
Clean the hub and spigot so they are reasonably free from dirt, mud, sand,
gravel or other foreign materials. When installing pipe that has been cut,
make sure the sharp edge is removed. The sharp edge may jam against the
gasket's seals making joining very difficult. The sharp edge may be removed
by filing or tapping the edge with a ball-peen hammer.
-
Fold and insert the gasket into the hub. The gasket must be inserted into
the hub completely. Only the flange which contains the identification information
remains exposed on the outside of the hub.
-
Lubricate the joint following the manufacturer's recommendations. Sizes
2" through 15" may be lubricated using a manufacturer's recommended lubricant.
Some manufacturers recommend using an adhesive lubricant on large diameter
pipe and fittings (5"-15"). It should be noted that use of the adhesive
lubricant does not take the place of proper join restraint when required.
-
Align the pipe so that it is straight. Using the tool of your choice, push
or pull the spigot through all of the sealing rings of the gasket. You
will feel the spigot end of the pipe bottom out in the hub. Fittings may
be installed by using the tool of your choice or by driving the fitting
home by using a lead maul. To do this, strike the fitting on the driving
lug or across the full hub. Hit it as hard as necessary, the lead will
deform without harming the fitting. Using the lead maul is the fastest
and easiest way to install fittings on hub and spigot cast iron soil pipe.
Proper safety procedures should be observed in making the joint.
Hubless Joints
Hubless
cast iron soil pipe is joined by using the hubless coupling. Several different
types of hubless couplings are available. The following will outline the
installation procedures of hubless couplings that meet the requirements
of CISPI 310. It must be noted that these installation procedures are not
intended to be applicable for couplings other than those manufactured in
accordance with CISPI 310. These couplings are manufactured using a stainless
steel shield and clamp assembly and an elastomeric sealing sleeve conforming
to the requirements of ASTM C-564. The following steps should be taken
to ensure a proper joint.
-
Place the gasket on the end of one pipe or fitting and the stainless steel
clamp and shield assembly on the end of the other pipe or fitting.
-
Firmly seat the pipe or fitting ends against the integrally molded center
stop inside the elastomeric sealing sleeve.
-
Slide the stainless steel shield and clamp assembly into position over
the gasket and tighten the bands. The bands should be tightened using a
calibrated torque wrench set at 60 in./lbs. For larger diameter couplings
that have four bands, the inner bands should be tightened first and then
the outer bands tightened. In all cases, when tightening bands they should
be tightened alternately to ensure that the coupling shield is drawn up
uniformly.
Caulked Joints
Prior
to the late 1950's, the caulked joint was the only method of joining hub
and spigot cast iron soil pipe. To make a caulked joint the following steps
are used:
-
The spigot end of a pipe or fitting is placed inside the hub of another
pipe or fitting making sure that both are clean and dry.
-
Oakum is placed in the joint using a yarning iron and then packed to the
proper depth by using the packing iron. For specifying depth of lead for
each size and class see table below.
-
Molten lead is then poured into the joint. The molten lead is brought up
to the top of the hub.
-
After the lead has solidified and cooled somewhat, the joint is ready to
be caulked. Caulking is performed with inside and outside caulking irons.
Caulking the joint sets the lead and makes a leak-free joint.
Any time caulked joints are used, safety procedures should be observed
and protective equipment and clothing should be employed. Use customary
precautions in using or handling molten lead. If a horizontal joint is
to be made, a pouring rope must be used to retain the molten lead in the
hub.
Lead and Oakum Required to Caulk Cast Iron Soil Pipe Joints
Oakum
is made from a vegetable fiber and used for packing hub and spigot joints.
Cotton and hemp can also be used. These materials are usually twisted loosely
into strands or braided and formed into a circular or rectangular cross
section. A rough rule-of-thumb method for estimating oakum requirements
is to take 10 percent of the weight of the lead required for caulking.
Table 5 provides a more accurate method for estimating oakum requirements.
Lead
quantities can be roughly estimated by rule-of-thumb as 12 ounces per inch
of diameter as a minimum. Thus a 4 inch diameter pipe would require 3 pounds
of lead as a minimum. An 8 inch diameter pipe would require 6 pounds of
lead. This allows for skimming-off and for a reasonable loss due to spillage
in pouring. Table 6 lists suggested lead quantities for various pipe and
fitting diameters. The amounts shown apply only to cast iron soil pipe
and fittings made according to ASTM Standard A-74.
The
standards of the Lead Industries Association contain the specification
for lead quality. Lead for caulking purposes should contain not less than
99.73 percent of lead and no more than the following maximum allowable
impurities: .08 percent copper, .002 percent zinc, .002 percent iron, .25
per cent bismuth, .02 percent silver, and a total of not more than 0.15
percent arsenic, antimony and tin. The melting point for caulking lead
is 621 degrees F, and the proper pouring temperature is 790 - 830 degrees
F. The lead is ready for pouring when it becomes a cherry red. After cooling,
there is a shrinkage of approximately 5.8 percent from the liquid state.
NOTE: The caulked joint is a very time consuming method of joining
cast iron soil pipe. The vast majority of all hub and spigot cast iron
soil pipe installed today is joined by using the compression gasket.
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