AWWA D104:2017 pdf download.Automatically Controlled, Impressed- Current Cathodic Protection for the Interior Submerged Surfaces of Steel Water Storage Tanks
The purpose of this standard is to provide the minimum requirements for automatically controlled, impressed-current cathodic protection for the interior submerged surfaces of steel water storage tanks, including design, system compo- nents, quality of work, and installation. Refer to appendix B for operation, moni- toring, and maintenance considerations.
This standard can be referenced in specifcations for designing and install- ing automatically controlled, impressed-current cathodic protection for the interior submerged surfaces of steel water storage tanks. Te stipulations of this standard apply when referenced and then only to automatically controlled, impressed-current cathodic protection for the interior submerged surfaces of steel water storage tanks.
The following defnitions shall apply in this standard:
1. Anode: Te electrode of an electrochemical cell at which oxidation occurs. (Electrons fow away from the anode in the external circuit. It is usually at the electrode where corrosion occurs and metal ions enter solution.)
2. Anode life: Te anticipated number of years of service before anode replacement is required. In this standard, the two types of anodes considered are (1) seasonal or temporary and (2) long life. Te seasonal or temporary type of anode is considered to be a nominal 1-year life, and the long-life type of anode is considered to be a nominal 10-year minimum life.
3. Cathode: Te electrode of an electrochemical cell at which reduction is the principal reaction. (Electrons fow toward the cathode in the external circuit.)
4. Cathodic polarization: Te change in electrode potential in the negative (active) direction caused by current across the electrode/electrolyte interface.
5. Cathodic protection: A method of corrosion control that reduces the corrosion of a submerged metal surface by making that surface the cathode of an electrochemical cell.
6. Coating: All components of the protective coating system, the sum of which substantially isolates (electrically) the underlying metal from the electrolyte (water).
7. Conductivity: A measure of the ability of a material to carry an electric current, expressed in micromhos or Siemens per centimeter. In water, this depends on the total concentration of ionic species and temperature. Conductivity is the reciprocal of resistivity.AWWA D104:2017 pdf download.