Hydrotesting and mothballing
Hydrostatic water tests and mothballing are usually carried out during pipeline commissioning operations. Depending on the water used for these operations, integrity risks can be different.
The typical process of harmful effects of the water during hydrotesting and mothballing operations is as follows:
- water corrodes the pipe and the corrosion phenomenon decreases the dissolved oxygen content,
- when all the oxygen has been consumed, anaerobic conditions are attained. The water, which usually contains sulphates and bacteria, will be prone to sulphate reducing bacteria (SRB) proliferation.
Several types of treatment are possible:
- using a corrosion inhibitor effective when oxygen is present,
- removing oxygen from the water with an oxygen scavenger (Norust® SC), killing bacteria with a biocide (Bactiram®), and preventing corrosion with a corrosion inhibitor (Norust® SC),
- using a multifunctional product with a corrosion inhibitor, a biocide and an oxygen scavenger all in one specifically designed for the oil & gas industry: Norust® CR 486.