Underground Construction - October 2021 - 28

REHABTECHNOLOGY
Safety Tips, Best Practices
When Using Pneumatic Pipe Plugs
At Cherne Industries, safety is a top priority. We know that on
the job, accidents and deaths become even more tragic when you
realize they were preventable. Such is the case with the misuse of
pneumatic pipe plugs. When using them, understanding equipment
and job conditions are vital to contractor safety.
Cherne sets the standard for high-quality, reliable pipe plugs.
Although these products are built with safety in mind, they are only
as safe as the person using them. To practice safe plug usage at all
times, contractors must take the time to learn the proper procedures.
Below, we share four vital safety tips and best practices when
using pneumatic pipe plugs for municipal or commercial pipeline
testing, maintenance and repair. However, this article is not a
replacement for the product instruction manual and must be read
fully before using pipe plugs.
Never enter the danger zone
When a plug is in use, a danger zone exists that expands outwardly
in a cone shape from the manhole opening. Th e most important
safety measure is never to enter the danger zone in such a situation.
Remember that the total force exerted on a pipeline plug is
directly proportional to both the pressure and the pipeline area.
Th e amount of force behind a plug can be overwhelming.
To better understand the hidden danger you may face when
entering the danger zone, let's break down what happens when a
plug is used to hold back pressure.
Th e formula for calculating pipeline forces and pressures is:
Force = Pipeline Area × Pressure
Consider the following: an 8-inch plug used in a 4-psi (pounds
per square inch) test is subjected to over 250 pounds of force. Th e
same 4-psi test in a 48-inch diameter pipe is restraining over 7,200
pounds of force.
Standing in front of a plug during this type of air test would be
like standing in front of a loaded cannon with a lit fuse. A plug
defl ated before the back pressure is released can cause serious
injury and even death.
Preparation before using pipe plugs
Before beginning any job, be sure to follow the guidelines below
to prepare for the usage of pneumatic pipe plugs.
Select the proper plug and related equipment:
Every pipe plug has performance specifi cations listed on it and
in the product literature.
Determine the back pressure: Th e maximum back pressure
the plug must withstand is the pressure (air or liquid) in front
or back of the plug that it must restrain. Never exceed the plug's
back pressure rating. As explained in the previous section, the
total force exerted on a pipeline plug is directly proportional to
both the pressure and the pipeline area.
Select the correct plug size: Pipe plugs have a minimum and
maximum sealing size range. Always verify that the pipe's inside
diameter (ID) is within the plug's sealing (usage) range.
It's important to check the ID of the pipe to be plugged and match
it to the usage range of the pneumatic plug to make sure it will
work in the intended pipe
28 OCTOBER 2021 | UCONonline.com
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Underground Construction - October 2021

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