Ice pigging is a process in which an ice slurry is pumped through a pipe, forcefully removing unwanted deposits and leaving the pipe clean.[1] It has many applications in the water, sewage, and food industries.[2] Ice pigging was invented and first patented by Professor Joe Quarini of the University of Bristol.[3]

Process

Ice pigging differs from conventional pigging in that the “pig” inserted into pipes or fittings is not a solid object. The ice pig can flow like a liquid through such obstructions as valves and variations in pipe diameter. The ice pig can be inserted and ejected from the pipe using small-diameter fittings. If an ice pig does become stuck,

The process can be undertaken with pipes made of most common pipe materials, and on pipes with diameters ranging from 8 mm to 600 mm and lengths of several kilometres. The ice pigging process takes less time than traditional pigging methods for underground pipes and can be operated by fewer people.[4]

Minimal enabling work is required to insert the ice pig and remove it.[5] Minimal enabling work decreases the disruption of water supply in applicable fields, along with less traffic disruption.[6]

Any water flushing method (such as uni-directional flushing, air/water flushing, or closed loop with side stream filtration) is limited by the flow of liquid through the pipework due to a boundary layer of slower flow that occurs at the pipe surface. As a result of this boundary layer the wall shear generated is negligible, even at high flow rates. Because the ice pig moves through the pipework like a solid object, movement concentrates at the pipe wall resulting in high wall shear even at velocities as low as 0.2 m/sec.

The process provides a low risk solution to cleaning a pipe compared to traditional pigging as, in the unlikely scenario of the ice becoming stuck, it can be left to melt and then flushed out.

Environmental impacts

Ice pigging uses less water and requires less cleanup than traditional flushing or underground pipe pigging techniques.[7] The production of ice slurry demands a substantial amount of energy.

Research and development

The University of Bristol has produced a paper entitled "Investigation and development of an innovative pigging technique for the water supply industry." in which they have detailed the research that they have carried out. It looks particularly at how the properties of the ice pig behave with different ice fractions and varied levels of particulate loading as well as looking into the effects of shear strength, viscosity, and heat transfer characteristics.[8]

Process

  • Ice slurry is inserted into the pipe via an existing small-diameter fitting
  • The pig is pushed through the pipe using just one pipe volume of water and then the pipe is flushed for a short period returning the water quality to its usual limits typically using 1/4 to 1/2 of the pipe volume,[9] Total water usage is therefore typically 1.5 times the volume of the pipe to be cleaned.
  • The ice-pigging process can be used in pipes of any material and will not damage the internal structure of the pipe.
  • The ice pigging process takes less time than traditional pigging methods for underground pipes and can be operated by fewer people reducing labour costs.[4]
  • Ice pigging is a low-risk technique and minimal enabling works are required to insert the ice and remove it.[5]
  • Ice pigging in manufacturing can reduce effluent costs and provide product recovery benefits when compared to water flushing.[10]

References

  1. ↑ "Ice Pigging Effective & Low-Risk Pipeline Cleaning using Ice Slurry". Ice Pigging.
  2. ↑ "Systems Centre". Archived from the original on 2013-03-05. Retrieved 2013-05-20.
  3. ↑ "Ice Pigging | Research | University of Bristol". www.bristol.ac.uk. Retrieved 2022-02-15.
  4. 1 2 "Ice Pigging". December 3, 2012. Archived from the original on May 28, 2013. Retrieved May 20, 2013.
  5. 1 2 "Process & Production: Breaking the ice for cleaner pipes". 7 December 2009.
  6. ↑ "Cleaning our mains - Ice pigging - Affinity Water". www.affinitywater.co.uk. Retrieved 2021-02-03.
  7. ↑ http://info.ncsafewater.org/Shared%20Documents/Web%20Site%20Documents/Spring%20Conference/SC13_Abstracts/Water/TuesWater6-IcePigging-Abstract_RMoore-IcePigging.pdf%5B%5D
  8. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2016-03-04. Retrieved 2013-05-20.{{cite web}}: CS1 maint: archived copy as title (link)
  9. ↑ "Advantages of Ice Pigging". 2011-10-10. Archived from the original on 2013-03-24.
  10. ↑ "Ice Pigging Videos | Zap Ice Pigging". Archived from the original on 2013-12-07. Retrieved 2013-10-08.

Further reading

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