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#1
03-06-2011, 11:41 AM
 Pavinsteelman WeldingWeb Tradesman Join Date: Feb 2011 Location: South Plainfield NJ Posts: 334
Plate Weight

Hi being a bridge estimator taking off weight of plate is a daily job . The way Iearned is this formula. 3.40832 x number of pieces x thickness in inches x width in inches x length in feet = pounds example 1 plate .5 x 96" x 40' = 6535 lbs. Hope that helps ? Some use plate weight tables in pounds per square foot or 490 pounds per cubic foot. The easy way is to use Fabtrol punch it in and it weighs up and mults the plate for you . Hope this helps !! John
#2
03-06-2011, 02:34 PM
 Pavinsteelman WeldingWeb Tradesman Join Date: Feb 2011 Location: South Plainfield NJ Posts: 334
Re: Plate Weight

Ooops made a mistake 3.4832 is formula !!! John
#3
03-06-2011, 04:35 PM
 denrep Master Welder Join Date: Nov 2006 Posts: 5,444
Re: Plate Weight

Interesting.
Of course the multiplier can be eliminated if calculations don't mix feet and inches.

I usually have to do the rough math in my head, and the shapes aren't always simple flats, so I go about it slightly differently.

My favorite rules of thumb for carbon steel are:
40# per square foot @ 1" thick
-or-
10# per square foot @ .250" thick
-or-
.283# per cubic inch.
In practice, for easy math, I use: .250# per cubic inch and add 10% to the total if I need to get a little closer.
-----------------

For the deck plates, I would probably have mentally calculated:

8' x 40' = 320 total square feet

(then, because it's easy base-10 math: 320' @ 10# for 1/4' thickness)
320 x 10 = 3200# @ 1/4" thickness
(then, because it's simple doubling)
3200 x 2 = 6400 @ 1/2" thickness

For an estimate of 6400# vs the theoretical 6535#

I may have been off by about 2%, -if the plates are 100% true and consistent- but that's usually close enough and I can crunch the numbers while pacing the dimensions as we talk about the weather.

Good Luck

Last edited by denrep; 03-06-2011 at 04:40 PM.
#4
03-06-2011, 05:14 PM
 Brett WeldingWeb Craftsman Join Date: Apr 2006 Location: Sydney Australia Posts: 1,068
Re: Plate Weight

I have found this useful
http://www.steelforge.com/steelweights.htm
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#5
03-07-2011, 09:08 AM
 ExpatWelder WeldingWeb Foreman Join Date: Apr 2010 Location: Ghana Posts: 508
Re: Plate Weight

I have always used: Length X Width X Thickness X .2836 (Came out to 6534.144 pounds, must be close)
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#6
04-04-2011, 12:12 AM
 Donald Branscom WeldingWeb Craftsman Join Date: Dec 2007 Location: Guerneville Ca Posts: 1,682
Re: Plate Weight

Quote:
 Originally Posted by ExpatWelder I have always used: Length X Width X Thickness X .2836 (Came out to 6534.144 pounds, must be close)
Very good formula. I tested it. 12"x 12" x .250 plate =10.2 lbs.,. right on the money.

Where does that .2836 come from?
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#7
04-04-2011, 12:21 AM
 Sandy Master Welder Join Date: Jan 2004 Location: Northern Cal., Shasta County Posts: 6,437
Re: Plate Weight

Quote:
 Originally Posted by Donald Branscom Very good formula. I tested it. 12"x 12" x .250 plate =10.2 lbs.,. right on the money. Where does that .2836 come from?
Pounds per cubic inch. Generally rounded to .284 for small amounts. I guess on a mile long bridge that .0004 would make a difference tho.
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#8
05-08-2011, 02:34 AM
 novicepipewelder Solderer Join Date: Feb 2011 Posts: 5
Re: Plate Weight

Steel is 490 pounds per cubic foot. the formula I was taught is this, First you convert all your lengths to inches ( length X width X thickness) divided by a cubic foot which is (12x12x120) OR 1728.

so again that is length X width X thickness divide the answer by 1728, and then multiply this answer by the weight of the material per cubic foot, steel being 490.

This works for all materials you just need to know the weight per cubic foot.

If you are needing the weight of pipe its almost the same, Again you get all of your measurements converted to inches.

take the diameter of the pipe X 3.1416 (PIE) X the length of the pipe X the thickness.

Then divide by 1728
Then multiply by the material's weight per cubic foot

And For round bar
again in inches
get the radius of the bar
multiply the radius times itself X 3.1416 X length
divide by 1728
then multiply by the material's weight per cubic foot

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