Hazards of Growth-Ring in Water Pipeline and Cleaning Technology

Due to the effects of physics, chemistry, electrochemistry and microbiology, growth-ring is formed in water pipelines during operation all the year round. It is an irregular ring that composed of sediments, corrosion, scales and biofilm. There is an annular laminar layer along pipe wall at low flow velocity. Caused by a sharp increase of flow velocity, the damage of the laminar layer will scour the growth-ring. Moreover, sediments, corrosion, scales and biofilm can be readily scoured into water and then lead to deterioration of water quality. Growth-ring not only influences water quality, but also reduces ability of transportation and water pressure, because of the reduction of flow rate and runoff, increasing the resistance coefficient and thickening the growth-ring. Although previous pipe cleaning methods can effectively remove the growth-ring, keep pipes clean, reduce secondary pollution and prolong pipe life, there are many shortages of these methods. Hence the application of these methods is limited. In this study, a new kind of pipe cleaning method with gas-water pulse and water-hummer was introduced. It is a highly efficient, water-saving and low-cost method for growth-ring removal.