Metric Practice Guide for the Welding Industry


Metric Practice Guide Welding Industry AWS A1.1:2016


The AWS (American Welding Society) Metrication Policy states, in part, “The AWS supports a timely transition to the use of SI units.” Stipulations like this are important because the United States is currently the only industrialized nation that still predominantly uses the inch-pound units of the Imperial system, as opposed the near-universal metric system. While this operates relatively well within many facets of American society, it is ideal for industry, commerce, mathematics, and science to take advantage of the metric system.

For this purpose, AWS has released AWS A1.1:2016 - Metric Practice Guide for the Welding Industry. Through its guidance, those involved with the US welding industry can assure reliability through unit conversions and remain competitive in international markets.

As discussed in the foreword of the AWS A1.1:2016 standard, the United States’ relationship with the metric system extends back to beginnings of both the country and the system of measurement, in the late 1700s, when two renouned founding fathers, Benjamin Franklin and Thomas Jefferson, strongly supported decimal measurement and decimal currency. In fact, George Washington, in his first annual message to Congress, stated,

“Uniformity in the currency, weights, and measures of the United States is an object of great importance, and will, I am persuaded, be duly attended to.”

Franklin and Jefferson were successful in attaining their desired currency for their new nation, but the Imperial system that had become commonplace during British rule remained in favor. However, despite this decision, America’s first leaders bore a significant influence on the French measurement leaders who were developing the decimal metric system that Napoleon later officially adopted.

It is important to note that, while it may not be overtly present, the U.S. has technically adopted the metric system. In 1866, Andrew Jackson made its units legal for use in all commercial and legal dealings, and the Metric Conversion Act of 1975 designated the metric system “as the preferred system of weights and measures for United States trade and commerce.” However, this, as well as similar measures passed by the government, have been voluntary, allowing the Imperial system to prevail.

The AWS A1.1:2016 standard is a guide based off the International System of Units (SI), containing specifications for them, as well as derived units, prefixes, and rules for their use in in the welding industry and associated AWS documents. Furthermore, it addresses ways to convert from U.S. customary units to SI units.

As mentioned in the foreword of AWS A1.1:2016, simple conversion from one system to the other is not always a viable solution, as this can lead to rounding errors and the genesis of other incorrect data. An extreme example of this took place in 1999, when NASA used metric units and their subcontractor alternatively made use of U.S. units. Because of an error in their calculations, a $125 million Mars orbiter, after a 10-month journey to the red planet, was destroyed by coming into close contact with the Martian atmosphere.

AWS A1.1:2016 - Metric Practice Guide for the Welding Industry is available on the ANSI Webstore.
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