Corrosion control in long sub-sea oil pipelines

Many of the subsea pipelines in the North Sea are dosed with inhibitors to control corrosion. It has been normal oil production practice to select corrosion inhibitors for pipeline service by laboratory test methods and then to check on service effectiveness by online monitoring or testing. The long subsea pipelines have introduced uncertainties into traditional practice in that it is not normally possible to monitor close to the expected corrosion hazard area. The laboratory test techniques and monitoring methods required to give a sensible assessment of the corrosion hazards are described and discussed.