General.

This standard is a procedure for the application of metallic Thermal Spray Coating (TSCs) of aluminum, zinc, and their alloys and composites for the corrosion protection of steel. Required equipment, application procedures, and in-process quality control (QC) checkpoints are specified. This standard may be used as a procurement document. Annex A presents a fill-in-the-blanks model procurement specification. The flow diagram in Figure 1 provides an overview of the thermal spray coating process presented in this standard.

Not included in this standard are requirements for design and fabrication, thermal spray equipment qualification, coating selection, and operator and inspector certification. For successful thermal spray application, the steel structure and components should be designed and fabricated according to NACE Standard RP0178. Additional consideration should be given to weldments whose oxyfuel cut edges may affect hardness which may preclude adequate profile depth.

Safety.

The basic precautions for thermal spraying are essentially the same as for welding and cutting. Information can be found on Safety in the Safety Chapter in AWS Thermal Spraying: Practice, Theory, and Application; ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes;⁵ and NFPA 58, Standard for the Storage and Handling of Liquefied Petroleum Gases.⁶ Read and follow safety precautions in the manufacturer’s equipment technical instructions and manuals and the feedstock Material Safety Data Sheet. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Potential thermal spraying hazards include exposure to vapors, dust, fumes, gases, noise (from the spray gun), and arc ultraviolet (UV) radiation. Additionally, improperly used thermal spray equipment can create potential fire and explosion hazards from the fuel and carrier gases and a potential electrical shock hazard from the electrical and electronic equipment and charged wire spools. To minimize hazards, proper safety precautions shall be followed. Operators shall comply with the procedures in the safety references, the manufacturer’s technical manuals, and the material safety data sheets.

Thermal spraying can be a completely safe process when performed by an operator who follows the recommended precautionary measures, has a proper understanding of thermal spraying practices, and has knowledge, skill, and exercises care in using thermal spray equipment.

Units of Measure

This specification makes use of both the International System Units (SI) of units and U.S. Customary. The measurements are not exact equivalents; therefore each system must be used independently of the other without combining in any way. The specification C2.23M uses SI units. The specification with the designation C2.23 uses U.S. Customary Units. The latter are shown in appropriate columns in tables or within parenthesis ( ) when used in the text. Suitable conversions encompassing standard sizes of both can be made, however, if appropriate tolerances are applied in each case. 

5. AWS and ANSI standards can be obtained from Global Engineering, 15 Inverness Way East, Englewood, CO 80112- 5776. Telephones: (800) 854-7179, (303) 397-2740; fax (303) 397-2740; Internet: www.global.ihs.com.

6. NFPA standards available from National Fire Protection Association, One Batterymarch Park, Quincy, MA 02269-9101.