Method and apparatus for electrical surveys of offshore metal structures with correction for distance

摘要

In the present invention a method and apparatus for electrical surveys of offshore metal structures includes measuring the electrical potential difference between the structure and an electrolyte, such as sea water and/or the sea bottom, in which the structure is contained. Such measurements are made at roughly approximated recorded distance locations along the structure and the approximate distance information is corrected based on periodically taken accurate distance measurements. Provision is also made to correct data for line currents in the structure, and a method is disclosed for examining the effectiveness of an electrically insulating member connected in the structure. Moreover, an improved insulated wire having minimum insulation holidays and a method for making the same are disclosed.