What is the Inflation Pressure and Back Pressure

Pipe Plugs are mainly used for blocking and stopping the flow in the pipes temporarily. These flows can be water, sewage water, gas or petroleum. Thus, proper application of pipe plugs requires a special emphasis on pipe plug inflation and back pressure.

What is Pipe Plug Inflation Pressure?

Inflation Pressure, known also as Working Pressure, is the required pressure to inflate the plug by air. It is the pressure inside the plug that comes from the air supply (Compressor or hand pump).


What is Pipe Plug Back Pressure?

Pipe Plug Back pressure refers to the pressure that the pipe plug must withstand and it is the pressure inside the pipe which pushes the plug and forces it to move inside the pipeline. This pressure is also defined as the level difference between the upstream and the downstream ends of the test line; or, in other terms, the height of the water column behind the plug.


Net Back Pressure is the Pressure that the Pipe Plug must hold when there is a pressure from both sides of the plug and it is the difference between the Back Pressure and the Front Pressure as illustrated in the below sketch.

Net Back Pressure


Sometimes, our customers are confusing inflation pressure and back pressure. Although they are different, the pipe plug inflation pressure and back pressure are related to each other. So, when we examine the below formulization, we can understand clearly this.

When pipe plug is inflated with air, it effectuates pressure on the contact surface. Then, a friction force occurs between pipe surface and pipe plug. As a result, this friction force can prevent sliding of the pipe plug. Hence, if we inflate the pipe plug with less pressure, the plug can slip inside the pipe which can be so dangerous. That’s why you should always respect the instructions concerning the Inflation Pressure.

The following pipe plug back-pressure calculation formula will help you to design and plan your plugging operation correctly and will be the answer of the always asked question “what is the Back Pressure of this pipe plug?”


Calculating the Back Pressure force will help you to provide the suitable support for your application as PlugCo insists always on supporting and bracing the Pipe Plug against sliding whenever it’s under pressure.

PlugCo Pipe Plugs are suitable for testing as per the requirements of European Standard EN 1610. Also, they are produced with a size up to 144” (DN3600) and a back pressure up to 6 Bar. Pipe Plugs can work with 1-8 bar inflation pressure and can hold 0,5-6 bar back pressure.

Lastly, in order to see an application where Pipe Plug Inflation Pressure and Back Pressure are explained, please check our following video.