Gauge? 5

[Steelforbrains]

This is just a question out of curiosity. Does anyone know how gauges for sheet metal and wire are determine? Where did these measurements originate from? I know how the gauge of a shotgun is determined but I can't find any reference for the seemingly random metal thickness. Also where do standard pipe sizes come from? Why can't a 4" pipe just have a 4" ID?

 

[alexit]

Machinery's Handbook:

"The United States Standard Gage for iron and steel sheets and plates was established by Congress in 1893 and was primarily a weight gage rather than a thickness gage. The equivalent thicknesses were derived from the weight of wrought iron. The weight per cubic foot was taken
at 480 pounds, thus making the weight of a plate 12 inches square and 1 inch thick, 40 pounds."

 

[MintJulep]

Pipe sizes are easy.

If you measure every dimension of a piece of pipe, and none of them are 4 inches, then it's 4 inch pipe.

 

[Steelforbrains]

Alexit,
So then how is it determined what 11 Ga or 7 Ga are?

MintJulep,
Thanks for the explanation, it is so clear to me now...

 

[TBP]

Steel pipe was originally designated by the ID. It became apparent pretty quickly that the wall thicknesses were big-time overkill. Nobody was really too keen on changing the OD, since that would involve corresponding changes to all of the existing pipe dies, taps, fittings, valves, etc. Literally, the installed base in factories, buildings, powerhouses, railways, ships, etc would be obsolete. Not happening. By increasing the ID, you could get more flow through the same OD pipe, save on material costs and have the existing installations remain compatible with the new material dimensions.

 

[Barry1961]

Here is a chart showing the weights for gage size.

http://www.constructionwork.com/resources_details_1390wire_and_sheet_metal_gauges.html

Barry1961

 

[Steelforbrains]

Thank you TBP that was the best answer that I've heard yet. Barry1961 I have charts that show me what the different thicknesses are for different gages but I really want to know why 11 ga is .1196" unless its non ferrous then it is .0907". WHERE DID THESE NUMBERS COME FROM? Like a 12 gage shotgun, the barrel diameter corresponds to the number of lead balls, of the same size, that it would take to make a pound. So it would take 12 lead balls, 12 gage in diameter, to make one pound of lead. It is an odd system but at least it has some basis to it. I can't seem to get anyone to tell me why sheet metal/wire sizes are the way they are. I guess should just accept it and go on with my life...

 

[jsummerfield]

BTW, the sheet metal gauge where 11 gauge equals 0.1196 inch thickness applies to carbon steel - not stainless steel, not aluminum, not ... ... ... and not wire gauge too. Lotsa stuff on the web.


Gage # Sheet Steel  Strip & Tubing Aluminum Stainless Steel
6/0 ---- ---- 0.58 0.4687
5/0 ---- 0.5 0.5165 0.4375
4/0 ---- 0.454 0.46 0.4062
3/0 ---- 0.425 0.4096 0.375
2/0 ---- 0.38 0.3648 0.3437
0 ---- 0.34 0.3249 0.3125
1 ---- 0.3 0.2893 0.2812
2 ---- 0.284 0.2576 0.2656
3 0.2391 0.259 0.2294 0.25
4 0.2242 0.238 0.2043 0.2344
5 0.2092 0.22 0.1819 0.2187
6 0.1943 0.203 0.162 0.2031
7 0.1793 0.18 0.1443 0.1875
8 0.1644 0.165 0.1285 0.1719
9 0.1495 0.148 0.1144 0.1562
10 0.1345 0.134 0.1019 0.1406
11 0.1196 0.12 0.0907 0.125
12 0.1046 0.109 0.0808 0.1094


John

 

[Steelforbrains]

nevermind...

 

[JEB66]

In the table submitted by Barry1961, it shows the weight in oz/ft2. That is where the gauges came from. decreasing gauge increases the weight in uniform increments among groups of gauges

 

[Steelforbrains]

Thank you John and Jeb. Looking at my charts I can now see that. I didn't look at john's chart close enought to notice that it was showing weights and not thicknesses. Somehow I didn't notice that the weights incremented evenly between gages.