Underground Construction - December 2022 - 43

REHABTECHNOLOGY
Tips for Using Bypass Pipe Plugs
for Sewage Bypass
Pete Rogers
Pipe plugs are designed to perform three
essential functions: blocking a pipeline,
conducting an air test in a pipeline, and
bypassing effluent in an active pipeline.
Blocking a pipeline becomes necessary
during new installation or maintenance,
when effluent needs to be
temporarily stopped or a new pipe is air
tested for leaks.
Air testing is conducted in a new installation,
before placing a pipeline in
service, or when trying to locate a leak
in an existing line.
Bypassing is necessary when the flow
of effluent in a pipeline needs to be redirected,
usually to perform maintenance
or repair for a longer period of time,
when the flow cannot be stopped.
This article concerns sewage bypass
and selecting and using bypass plugs.
A bypass plug has a tube or hose
that's open at both ends and runns entirely
through the plug. Most bypass
plugs come with caps threaded onto the
bypass on the front of the plug.
Cherne's bypass plugs, called Muni
Balls because they are primarily used
in municipal sewers, are versatile. With
the cap on, the plug can be used for
blocking; with the cap removed, it can
be used for bypassing. In addition, when
the cap is adapted with air fittings, it can
be used to perform an air test.
Muni Balls are available from
three-quarters to 96 inches in diameter,
with bypass tubes ranging from a half
inch to 24 inches.
Types of bypassing
Bypass plugs are typically designed for
two types of bypassing: pump and gravity.
Pump bypassing involves installing
a Muni Ball in a pipeline upstream from
where maintenance or replacement work
needs to be conducted. The plug is installed
into the pipe, and a hose or pipe
is attached to the bypass on the front of
the plug. The hose is then connected to a
pump on the intake side and another on
the output side.
Then, effluent is pumped up and out
of the manhole, running downstream and
past where the work is being conducted,
before it is routed back into another manhole
where the effluent can continue. A
blocking plug is installed on the upstream
side of this manhole to prevent effluent
back from flowing toward the work area.
Gravity bypassing occurs when work
needs to be conducted in an active manhole,
but the flow cannot be blocked.
In this instance, two Muni Balls are installed
into both access pipes that feed
into the manhole. A hose is connected
between the bypasses of the two plugs so
the flow can continue while the manhole
remains dry.
Proper bypass plug selection
To select the correct bypass plug (or
Muni Ball) for an application, the following
questions need to be answered:
* What is the inside diameter of the
pipe you need to plug?
* How much volume must the bypass
Gravity bypass
UCONonline.com | DECEMBER 2022 43
accommodate? This impacts the
size of the bypass required. You can
obtain this information from your
project engineer.
* What are the back pressure
requirements? In other words,
how much pressure will the plug
be required to hold? (Pressure is
most commonly measured by either
pound per square inch, when the
pressure is coming from air; or feet
Muni Ball
Pump bypass
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