AWS C2.20／C2.20M pdf free download

AWS C2.20／C2.20M pdf free download.Thermal Spraying Zinc Anodes on Steell Reinforced Concrete.
3. Terms and Definitions
AWS A3.OM/A3.0. Standard Welding Ternis and Definitions, Including Ternis for Adhesñe Bonding, Brazing. Soldering, Thermal Culling, and Thermal S,raving, provides the basis for terms and definitions used herein. However, the following terms and definitions are included to accommodate usage specific to this document.
anode. The electrode of an electrochemical cell at which oxidation occurs. Electrons flow away from the anode in the external circuit. Corrosion usually occurs and metal ions enter the solution at the anode.
cathode. The electrode of an electrochemical cell at which reduction is the principal reaction. Electrons flow toward the cathode in the external circuit.
cathodic protection (CP). A technique to reduce the corrosion of a metal surface by making that surface the cathode of an electrochernical cell. Such protection can he provided using ICCP or SCP.
electrolyte. A chemical substance containing ions that migrate in an electric field.
feathering. Reducing the thickness of an edge of a coating, e.g., by masking or simultaneously increasing traverse speed of the thermal spray gun.
flash coat. A thin metallic coating usually less than 0.(X)2 in 10.05 rnmj in thickness.
holding period. The time between the start of final blasting for surface preparation and completion of thermal spraying.
impressed current cathodic protection (ICCP) system. A system of components including a power source external to the electrode system that provides a direct current to reduce the corrosion of a metal surface.
job reference standard. A job site pass/fail reference standard made from concrete and rehar, representative of the whole job or major sections of the job and the environmental conditions, with or without enclosure, and shall include areas showing blasting. metallizing. and connection to the reinforcement.
overspray. The excess spray material that is not being deposited on the part or area designated to be sprayed.
sacrificial anode. A metal that provides sacrificial protection to another metal that is more noble when electrically coupled through an electrolyte. This type of anode is the current source in SCP systems.
sacrificial cathodic protection (SCP). A type of cathodic protection where an active metal acts as a sacrificial anode when it is connected by metallic conductors to a less active metal in the structure to be protected. This specification is limited to thermally sprayed zinc anodes: however, sacrificial cathodic protection using thermally sprayed aluminum, magnesium. and alloys of aluminum, magnesium. and zinc are also in use.
thermal sprayed coating (TSC). A protective coating, as it pertains to this standard, applied to a surface using arc or flame spray coating processes.
thermal spray coating inspector. A person who is knowledgeable in the concepts and principles of thermal spray coatings and skilled in observing and measuring conformance to this standard.
4. Job and Contract Specification
4.1 Requirements
4.1.1 Summary of Requirements. Briefly summarize the background and requirements for this thermal spray job, i.e., zinc thermal spray coating on reinforced concrete as (I) a distributed anode for an ICCP system, or (2) a sacrificial anode for a SCP system:
In an ICCP system. the rebar is protected by a counter corrosion current applied by a power source through the thermal spray zinc anode. The zinc thermal spray anode must be electrically isolated from the rehar. When installing a thermally sprayed zinc anode for use in an ICCP system. a viable method to avoid any short circuits between the anode and the rehar should be specified.AWS C2.20／C2.20M pdf download.