Sunday, January 04, 2004

ASTM, etc.

Somewhere in the west Philly suburbs there exists an organization called ASTM International. They impact your life in more ways than you'll ever suspect, yet most of you probably don't even suspect their existence.

What's with ASTM, anyway? It is the acronym for the organization's original name, the American Society for Testing and Materials. Libertarians should love these guys, because they implement voluntary standards for materials that can be adopted in contracts and laws. The standards themselves are created primarily by subject matter exports who are familiar with the state of the art, not a pack of bureaucrats whose major consideration is self-perpetuation.

So what do they provide standards for? Just about anything. Soils for instance - wouldn't you like to know if your house is likely to go sliding off a cliff? ASTM has a test for the so-called "liquid limit" of soils, which can be used by civil engineers to measure soil stability.

How do they do it? According to fairly rigid procedures, the soil is mixed into a paste and placed in a shallow, spherically-shaped bowl. A tool of specific dimensions is used to create a trapezoid-shaped groove in the paste. Then the whole shebang is jarred repeatedly by a special apparatus a specified number of times, after which the width of the groove at the bottom is measured. From this the "liquid limit" is calculated.

The above is from memory from a job as a tech in the summer of 1979, so this might have changed since then. If you want to know the current standard, it'll cost you $38.00 if you buy it from ASTM. Don't all go at once or you'll bring down their server.

The same spec also offers the method for determining the "plastic limit". As I recall, this was affectionately known as the "turd test". The soil would again be mixed with water according to some strict rules, then the result was to be rolled into cylinders of as small a diameter as possible. The resulting diameter of the cylinder is used to calculate the "plastic limit".

Such a measure may not be too impressive - you might have been expecting super fancy machines, etc. And some standards might call for such elaborate apparatus. But in this application what is needed is something that can be done without elaborate preparations in the field, so that is what ASTM designed for this application.

ASTM offers thousands of standards, but they aren't the only ones - there are many others that affect you. There's NFPA, UL, ASME, ASHRAE, SMACNA, ANSI, AWWA, SAE, ICBO, CABO, BOCA, SBCCC, ASCE, IEEE, DIN and countless others. Expect tons of fun as I write about a few of those in future posts. (Yes, that's my idea of a cliffhanger - remember, I'm an engineer, not a writer or something). In the meantime you'll have to be content with this about ASME.

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