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FrothFlush is a high-energy technique applied to piping systems to remove loose mechanical debris, loosely adherent welding slag, and corrosion deposits from the pipe surfaces. It is also an effective replacement for conventional pigging of piping systems. FrothFlush is performed by generating a slug of water that has a large number of air bubbles mixed into it. This frothed slug is displaced through the piping system at velocities of 40 to 80 feet per second, minimizing movement effects at tee’s and elbows due to the cushioning effect of the air entrained in the frothed slug.

A Key Element of SigmaCommissioning™ Protocol

BEST’s FrothFlush process is one of the key elements of the SigmaCommissioning protocol. Our breakthrough post-construction cleaning process is the most efficient pipe and complex systems flushing technology for not only cleaning but also the drying of critical plant systems. It is used to remove particulate debris and salts from process systems such as:

  • Demin Water System

  • Condensate System

  • Boiler Feedwater System

  • Closed Cooling Water System

  • Process Piping

  • Process Heat Exchangers

  • Process Coolers

  • Overhead Fin Fan Units


The FrothFlush process will quickly flush these systems utilizing a minimum quantity of demineralized water. This process is particularly effective in cleaning residual hydrostatic test water, iron salts, and other debris that contaminates these systems during the construction process.

Figure 1 - Typical Pipe before FrothFlush

Figure 1 - Typical Pipe before FrothFlush

Figure 2 - Froth Former and Air Receivers

Figure 2 – Froth Former and air receivers

Figure 3 - Typical Pipe after FrothFlush

Figure 3 – Typical cleaned pipe after FrothFlush

The FrothFlush process injects slugs of two-phase “frothed” water at high velocities into the piping to be flushed. The effect of the high velocity combined with the surface tension of the bubbles in the frothed slug results in very high Reynolds numbers (indicating fully turbulent flow) at the pipe surfaces. Fully turbulent flow provides an effective scrubbing of pipe surfaces in the shortest amount of time without the need for chemical additives.

In practice, the volume of each slug is determined by the diameter of the pipe to be cleaned. The slug is formed in the BES&T proprietary slug former (Figure 2) and propelled into the pipe at 60-90 ft/sec (20-30 m/sec) with a discharge of compressed air. As the length being cleaned is constrained only by the amount of compressed air available, long lengths can be cleaned with a minimum of demineralized water.

In addition to using a very small amount of water, there are additional benefits provided by the FrothFlush. 

  • First, it easily conforms to changes in pipe diameter, enabling the cleaning of multiple pipe diameters without the need for a breakout at each change in diameter. See Figure 1 - shows the typical condition of the pipe. 


  • Second, it easily transitions into the branches of the piping system without significant temporary breakouts. 
See Figure 2 - shows the Froth former equipment.  


  • Third, the compressibility of the froth slug minimizes reaction forces transmitted to the tees, elbows, and reducers in the system being cleaned. See Figure 3 - shows typical results of cleaning a pipe like that in Figure 1.


THE RESULT:  a scoured pipe surface that is free from debris and salts, ready for the process fluid and significantly fewer strainer fouling issues.



FrothFlush Video


The FrothFlush flushing process accelerates removal of debris through the 6" clear Schedule 40 plastic piping used for demonstration purposes only, 150 Gallons at 85 PSI.

Benefits of FrothFlush
  • Less water consumed than conventional filled flushing techniques

  • Less equipment required to reach a beneficial range of turbulence in piping systems

  • Reactive forces are reduced or eliminated due to compressibility of froth slug

  • Greater debris carrying capabilities because of the apparent viscosity of the two-phase slug

  • Can be performed with minimal impact to adjacent work

  • Eliminates safety issues associated with gas blowing on fuel supply piping

  • Takes less time to set-up and perform than conventional flushing or pigging

FrothFlush Process Using Froth Former: 

FrothFlush Process Using Froth Former.

Typical types of debris in the pipe: phone and particles of all sizes:

Typical types of debris in pipe: phone and particles of all sizes.
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