To enhance the anti-corrosion performance of materials and ensure public safety, the Bureau of Standards, Metrology and Inspection (BSMI) has revised the CNS 1247 "Methods of test for hot dip galvanized coatings," the CNS 8503 "Recommended practice for hot dip galvanized coatings," the CNS 10007 "Hot dip galvanized coatings on iron and steel" and the CNS 14771 "Zinc-coated (Galvanized) steel bars for reinforced concrete". The revisions are based on the ISO standard, the JIS standard and the ASTM standard.
Iron and steel are often used in modern architecture such as factories and mass rapid transit systems. Corrosion, however, causes considerable damage and greatly reduces the lifespan of iron and steel in products. This is especially a problem for Taiwan because it is located in the oceanic monsoon region and has high temperature and high humidity. According to an estimate made by advanced countries, the loss caused by corrosion is about three to four percent of the GDP. Based on this estimate, the loss caused by corrosion in Taiwan amounts to more than one hundred billion NTD per year, not taking into account damages to the environment (ex. corrosion in underground pipelines) and construction accidents. Anti-corrosion is an important issue for countries all around the world.
One of the most common and effective ways used by advanced countries to prevent corrosion is hot dip galvanized coatings. In the case of a steel product with galvanized coating, corrosion is prevented because zinc is more active than steel and oxidizes first. Also, since the corrosion rate of zinc is much slower than that of iron and steel, the lifespan of steel can be extended. A good example would be the unpainted lamp posts and traffic sign posts. With galvanized coating, the corrosion-resistant posts can last for decades. In Taiwan, products small as bolt and big as bridges are now coated to prevent corrosion.
The BSMI said that the revision focuses on enhancing the average thickness of the coating and methods of test for adhesion. The preparation process before coating and coating repair guidelines are also included in the revision to improve anti-corrosion performance.
For more information, please visit CNS Online Service at www.cnsonline.com.tw.
Agency in charge: Department of Standards (First Division)
Contact person: Miss HSIAO-CHING WENG
Telephone:(02)3343-5150