The initial preparation for a cathodic protection system is of prime importance. A competent design that accounts for all factors included in the system must be foremost in considering the application of cathodic protection. The usual first step is the preparation of a cathodic protection system design proposal. The Owner of the facilities or the consulting firm that is in charge of the operation of the facilities, supplies basic information. Such information would include the following:
- Location of facilities (usually in the form of an overall map)
- Material of which facilities are constructed (i.e. steel, aluminum, etc.)
- Size of facilities (i.e. length, diameter, etc.)
- Condition of facilities (i.e. new vs. old, bare vs. coated, etc.)
- A.C. power availability
- Land easement availability
Interior Corrosion Services’ design proposal would contain all expected costs that would be incurred in each of the phases of the application of cathodic protection.
The next step is to perform the preliminary field/office engineering that would clearly define the requirements of the system under consideration. An outline of this phase follows: Drawings are prepared of each central site where cathodic protection systems are required. These would show locations of all detectable buried structures as well as all visible facilities.
Soil electrical resistivity readings are obtained throughout these areas to determine the soil corrosivity and the optimum ground-bed location. Current requirement testing is desirable to clearly define the current required and avoid under or over design. It also exposes unexpected situations prior to construction such as poor quality coatings or electrically discontinuous facilities.
Static pipe-to-soil potential readings are obtained at all points of access throughout the system.
All field data obtained is tabulated and analyzed and a formal Cathodic Protection Design Report is submitted. The report outlines all conditions encountered and provides the optimum cathodic protection system for the subject facilities and includes As-Proposed Installation Drawings.
Firm costs for the remainder of the project would be included in this report. Costs would reflect any discrepancies found in relation to the initial information received. The report is then forwarded to the client for review and final approval to proceed with the construction phase.