CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.
Issue link: http://coatingspromag.epubxp.com/i/72303
Mortar linings protect steel from corrosion through passivation and retarding oxygen penetration to the steel substrate. PHOTOS COURTESY OF BY SYLVIA C. HALL, PE Editor's Note: This is the second part of a two-part series exploring mortar coatings. Part one, "Mortar: The Forgotten Coating" can be found in CoatingsPro, March 2012. T ransmission of water for residential, industrial, and agricultural uses requires large diameter pipelines, and steel pipe is often specified. These pipelines typically range from 1' (0.3 m) to more than 12' (3.7 m) in diameter. This public infrastructure is typically expected to have a minimum service life of 50 to 100 years. To preserve this buried, and thus hidden, asset from the corrosive effect of the transported water, the lining system must be able to withstand the stresses placed on it during handling, installation, backfilling, and service. Some of these stresses to the lining take the form of pipe def lection and pressurization, abrasion from particulates in the transported water, pipe settlement, and liquid and vapor water penetration. AMERON INTERNATIONAL CORPORATION Linings have been used for more than 175 years to protect the interior of steel water pipelines from corrosion. As demon- strated over the years, some lining systems are better than others at extending the service life of water transmission pipelines with virtually no maintenance. Some systems, for various reasons, are no longer used. Other systems introduced in the past 15 years have yet to prove their ability to provide long-term service life in actual installed conditions. The requirements of lining systems used on large-diame- ter steel water pipes are primarily given in internationally used waterworks standards, such as those developed by the American Water Works Association (AWWA). The predom- inant l ining currently used is port land cement mortar. However, other linings, such as coal tar enamel, liquid and fusion-bonded epoxies, and polyurethanes, have been or are currently being used but to a much lesser extent, as shown in Table 1. 48 CoatingsPro J July 2012