Selecting the right temporary coating

摘要

Temporary coatings preserve the quality of tube or pipe after it is manufactured until it is received by the end user. The primary functions of this type of coating are to prevent the forma-tion of red rust (iron oxide on steel pipe) or white rust (zinc oxide on galva-nized pipe) during storage and trans-portation and to ease the application of finishing paint.Most temporary coatings are destroyed when the pipes or tubes are put through a fabricating process, such as welding, bending, or finishing. Depending on the application, it may be necessary to paint the finished product for aesthetics and to prevent corrosion.Four main types of temporary coatings are applicable for steel pipe and tube operations. These are conventional sol--ventborne coatings, waterborne coatings, ultraviolet (UV) coatings1 and chromate--based conversion treatments.The main criteria for choosing a coat-ing are conformance to federal, state, and local laws for volatile organic compound (VOC) emissions in the areas where the pipe will be coated; the capital equipment investment needed to set up the coating line; the cost of the coating per square foot of coverage; the quality of the coat-ing; ease of application; and drying time. As environmental laws become stricter, the amount of VOCs becomes an increas-ingly significant factor.