Pipeline Hydrotesting & Flooding Water

UV Treatment of Pipeline Flooding & Hydrotesting Water

Before natural gas or oil is transported through new pipelines, the entire length of the pipeline assembly is pressure tested using either fresh water or seawater, and is the final construction ‘quality assurance’ test before the pipeline is put into operation.  The pressure test is held for a specific amount of time, from between 1 day and 100 days, to ensure structural integrity before the pipeline is placed into operation.

The water used for pipeline flooding and hydro-testing testing has for some time been known as a potential source of microbial infection, containing natural concentrations of SRB’s (Sulphate Reducing Bacteria), Acid Producing Bacteria and Slime Forming Bacteria, that if left untreated, pose a range of negative consequences including: -

  • Microbiological induced corrosion
  • Production of highly hazardous hydrogen sulphide gas H2S
  • Formation of biofilms and slime
  • Formation of Extracellular polymeric layer (creates bypasses of untreated water)
  • Damage of equipment and components (e.g. pumps, pipework)

 

UV disinfection: A highly effective solution for pipeline flooding water. 

Traditionally, chemical biocides such as Glutaraldehyde and THPS have been used to prevent bacterial growth, however strict limitations on discharges to the environment of wastewater following completion, together with the high cost of chemical biocides have seen operators look for alternative water treatment solutions.    

Over the last 5 years, UV disinfection of fresh water, brackish water and seawater has gained prominence as an alternative technique to using chemical biocides for controling micoorganisms and bacteria such as SRB's.  As a chemical-free technology, UV treatment has been successfully used in the field by leading operators on some of the worlds’ largest and most prestigious pipeline commissioning projects including the Nord Stream (Baltic Sea) and Castor (Caspian Sea) pipelines. 

When using UV disinfection with a filtration package and food grade oygen scavenger as the primary technique for controlling bacterial growth, operators have been able to fully eliminate the use of hazardous biocides from the process, significantly improving the environmental profile of the project and lowering operational costs.

Above: atg UV Technology UV disinfection package treating 3,000 m3/hr of seawater (SRB reduction) used for the flooding and hydrotesting of the Nord Stream - Russia to Germany gas pipeline. 

 

Benefits of UV Treatment: -

  • UV is a chemical-free, safe solution, widely used for drinking water and cannot be overdosed.
  • Eliminates chemical transportation, storage and handling.
  • Environmentally friendly, green technology
  • High disinfection efficency - >4 log (99.99%) of SRB's with a single pass through the UV system
  • Safe, low risk technology to operate 
  • Very low operation & maintenance requirements
  • Compact footprint & low weight solution
  • Reduced OPEX costs compared to other available technologies
  • Successful, field proven technology