how is the thickness of sheet metal measured
Sheet metal In most of the world, sheet metal thickness is consistently specified in millimeters. In the US, the thickness of sheet metal is commonly specified by a traditional, non-linear measure known as its gauge. The larger the gauge number, the thinner the metal. Commonly used steel sheet metal ranges from 30 gauge to about 7 gauge. Gauge differs between ferrous (iron based) metals and nonferrous metals such as aluminum or copper; copper thickness, for example is measured in ounces, which represents the weight of copper contained in an area of one square foot.
17th Street Canal On 10 November 2005, an article in the Times-Picayune revealed that sonar soundings discovered that the steel sheet pilings of the levee floodwall were 2.1 m (7 ft) less deep than engineering specifications. Sample pilings pulled up were found to be of the length specified in the design (17 feet), but it was then revealed that this length was less than the actual depth of the canal, in retrospect an obvious engineering mistake. Current analysis concludes that the catastrophic breach was due to faulty design, rather than storm surge higher than what the canal was designed to withstand. According to an article published in the August 2015 issue of the official journal of the World Water Council, the Army Corps of Engineers misinterpreted the results of a Sheet Pile Load test (E-99 Study) conducted in the mid 1980s and concluded they needed to drive sheet pilings to depths of not more than 17 feet, rather than the necessary 31 to 46 feet. This move saved millions but greatly reduced overall engineering reliability.[4]