The practice describes a
procedure for making joints with PVC plastic pipe both plain
ends, fittings, and bell ends, by means of solvent cements.
These procedures are general ones for PVC piping. In
non-pressure applications, simplified procedures may be
used. Manufacturers should supply specific instructions for
their particular products. The techniques covered are
applicable only to PVC pipe, both plain, bell-end, and
fittings of the same classes as described. Pipe and fittings
are manufactured within certain tolerances to provide for
the small variations in the extrusion, bell-end, and molding
processes and are not to exact size.
To consistently make good
joints, the following should be clearly understood and
adhered to:
Pipe
and Fittings
The pipe and fittings should
meet the requirements of current applicable piping
standards.
Solvent
Cements
The solvent cement should
meet or exceed applicable standards. Check with local and
state codes concerning product requirements.
Selection
of Solvent Cements
Solvent cements are available
in a variety of viscosities and wet film thickness to cover
the range of pipe sizes for 1/8 to 12 inch and for
interference fit joint as well as noninterference joints, as
found is some Schedule 80 pipe and fittings. One of the
general principles of solvent cementing that should be
strictly adhered to is: sufficient cement must be applied to
fill the gap between the pipe and fitting. The ability of a
solvent cement to fill a gap in a pipe joint can be
determined by considering its viscosity and wet-film
thickness. Solvent cements are broken into three
classifications, Regular Body, Medium Body, and Heavy Body.
Some manufacturers also have products classified as Extra
Heavy Body cements. These products are most commonly found
in industrial applications using larger diameter pipe and
fittings.
Storage Of Cements, Cleaners, And
Primers
PVC solvent cements should be
stored in a cool place except when actually in use at the
job site. These cements have a limited shelf life when not
stored in hermetically sealed containers. Screw top
containers are not considered to be hermetically sealed.
Consult manufacturers' for specific storage recommendations
on storage conditions and shelf life. The cement is
unsuitable for use on the job site if it exhibits an
appreciable change from the original viscosity, or if a sign
of gelation is apparent.
Restoration
of the original viscosity or removal of gelation by adding
solvents or thinners is not
recommended.
Cleaners
Cleaners are of two types,
chemical cleaners and mechanical.
Chemical cleaners are a blend
of solvents formulated to remove surface impurities (oil,
dirt, etc.) and surface gloss from pipe and
fittings.
Mechanical cleaners are fine
abrasive paper or cloth (180 grit or finer) or clean oil
free steel wool. These may also be used to remove the above
listed impurities for pipe and fittings
surfaces.
Primers
Primers should meet or exceed
ASTM Standard Specification F 656.
Most City and State codes
require these and other code approvals. Always
check with governing authority before using any non approved
products.
There exists a common
misunderstanding that if a cleaner is used, a primer is not
required, and vice versa. It is important to note that
cleaners and primers are intended for different functions
and should not be considered interchangeable.
Cutting Pipe
Cut pipe square with the
axis, using a fine tooth hand saw and a miter box, or a fine
tooth power saw with suitable guides. Wood working blades
may also be used. A rotary cutter may be used if the cutting
blades are specifically designed for cutting plastic pipe in
such a way not to raise a burr or ridge at the cut end of
the pipe. If other tools are not available, a standard
rotary metal pipe cutter may be used, provided great care is
taken to remove all the ridge raised at the pipe end by the
wedging action of the cutting wheels. Failure
to remove the ridge will result in the cement in the fitting
socket being scraped from the socket surface, producing a
dry joint with a high probability of joint
failure. Remove all burrs
with a knife, file, or abrasive paper.
Joint Preparation
Failing to chamfer or deburr
the edge of the pipe may remove the cement and softened
material from the fitting socket, may result in a leaking
joint.
Dry Fit Testing
The solvent cement joint is
designed so that there will generally be interference of
pipe wall with the fitting socket before the pipe is fully
inserted. Insert the pipe into the fitting and check that
the interference occurs about 1/3 to no more that 2/3 of the
socket depth. When pipe and fittings are at their tolerance
extremes or when Schedule 80 pipe is used, it may be
possible to fully insert the dry pipe into the fitting
socket until it bottoms. If this occurs, the fit between the
pipe and fitting must be snug. If the fit is loose or
wobbly, other pipe or fittings should be selected which
gives a proper fit.
Cleaning
Surfaces to be joined must be
cleaned and be free of dirt, moisture, oil, and other
foreign materials. If this cannot be accomplished by wiping
with a clean dry cloth, a chemical or mechanical cleaner
must be used.
Applicator Size
Apply the cement with a
natural bristle, nylon brush or suitable applicator, using a
1/2 inch brush or dauber for nominal pipe size 1/2 inch and
less, a 1 inch brush or dauber for pipe up through 2 inch
nominal pipe size, and a brush at least 1/2 of nominal pipe
size for sizes above 2 inch, except that for pipe sizes 6
inches and larger a 2-1/2 inch brush or applicator is
adequate. Other applicators may be used provided their use
results in an equivalent amount of cement being applied to
the joining surfaces. Remember, both surfaces must be wet
before assembling the pipe and fitting. Failure
to apply adequate cement to both the pipe and fitting
surfaces may cause joint failures.
Application of Primer and Cements
PVC solvent cement is fast
drying, and therefore the cement shall be applied as quickly
as possible, consistent with good workmanship. It may be
necessary for two workers to perform this operation for
larger sizes of pipe and fittings. Under conditions of high
atmospheric humidity, quick application is very important to
minimize condensation of moisture from the air on the cement
surface. The surface temperature of the mating surfaces
should not exceed 110 degrees F (45 degrees C) at the time
of assembly. In direct sunlight or in ambient temperatures
above 110 degrees F. The pipe temperature may be reduced by
swabbing the surface to be cemented with clean wet rags
provided the pipe is thoroughly dried before the primer and
cement are applied.
First apply primer to inside
socket surface using a scrubbing motion to ensure
penetration. Next soften surface of male end of pipe, to be
inserted into socket, to depth of fitting socket by
uniformly applying a liberal coat of primer. Be sure entire
surface is well softened. Without delay, apply cement to
pipe while the surfaces are still wet with primer. Apply
cement lightly but uniformly to inside of socket, taking
care to keep excess cement out of socket. In extreme
conditions, it may become necessary to apply a second
application of solvent cement to the pipe end
only.
Special
Instructions for Bell-End Pipe
The above procedures may be
followed in the case of bell-end pipe EXCEPT
that great care should be taken not to apply an excess of
cement in the bell socket. This
precaution is particularly important for installation of
bell-end pipe with a wall thickness of less than 1/8 inch (3
mm).
Joint Assembly
Immediately after applying
the last coat of cement to the pipe, and while both the
inside socket surface and the outside surface of the male
end of the pipe are SOFT
AND WET with solvent
cement, forcefully bottom the male end of the pipe in the
socket. Turn the pipe and fitting 1/4 of a turn during
assembly to distribute the cement evenly.
NOTE:
The 1/4 turn should be completed before the pipe reaches
full socket depth of the fitting. Assembly should be
completed in 20 seconds or less after the last application
of cement. The pipe should be inserted with a steady even
motion. Hammer blows should not be used. If
there is any sign of drying of the cement surfaces, due to
delay in assembly, the surfaces should be
recoated, taking care
again not to apply a surplus of cements to the inside of the
socket, particularly
in bell-end pipe. As large
axial forces are necessary for the assembly of interference
fit joints in large size pipe, two or more workers are
needed for such joints. Mechanical forcing equipment, such
as come-along or levers and braces may also be necessary.
Until the cement is set in the joint, the pipe may back out
of the fitting socket not held in place for approximately 1
minute after assembly. Care should be taken during assembly
not to disturb or apply any force to joints previously made.
Fresh
joints can be destroyed by early rough
handling.
After assembly, wipe excess
cement from the pipe at the end of the fitting socket. A
properly made joint will show a bead around its entire
perimeter. Any gaps at this point may indicate a defective
assembly job, due to insufficient cement or the use of
light-died cements on large diameter where standard or heavy
bodied should have been applied.
Installation
After the set period, the
pipe can be carefully placed in a prepared ditch and snaked
from side to side. Prior to backfilling, the pipe shall be
brought to approximate operating temperature either by
shading backfilling, or by filling with water, or by
allowing to stand overnight. The pipe system should be
allowed to stand vented to the atmosphere prior to pressure
testing. The set period before the system is pressure tested
will depend on the specific cement, the size of the pipe,
the ambient temperature, and the dry joint tightness.
Necessary cure time can vary from minutes to days depending
on conditions and the solvent cement used. A general rule,
relatively short cure periods are satisfactory for high
ambient temperatures with low humidity, small pipe sizes,
quick drying cements, and tight fitting joints. Longer cure
periods are required for low temperatures, large pipe sizes,
slow drying cements, loose joints, and relatively high
humidity. Shade backfill, leaving all joints exposed so that
they can be examined during pressure tests. On long runs
pressure tests should be performed on sections no longer
than 5000 feet. Test pressure should be 150% of system
design pressure and held at this pressure until the system
is checked for leaks, or follow the requirements of the
applicable codes, whichever is higher.
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