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Up Topic Welding Industry / General Welding Discussion / Steel expansion
- - By sparksandslag (**) Date 01-12-2014 02:32
Been lurking in the background for several years, gleaning knowledge from the experience of all those who post on here.  One thing that I have not seen is a discussion of the rate of linear expansion  for steel as it is heated.  Where I am going with this is as follows:  I've decided to build a set of gates for the  driveway to my house.  I am planning to use 1 1/2" square tubing, 11 gauge for the frames.  The gates will be +/- 8' wide each.  From my experience in hanging tubular farm gates, I know that the suckers will "grow", and if you're not careful, you have more gate than you have opening. Don't want that to happen in this case.  Does anyone have a formula, experential knowledge or whatever that can tell me how much "growth" per linear foot I can expect with the material I plan to use?  Any assistance will be appreciated.
Parent - - By Cactusthewelder (*****) Date 01-12-2014 02:49
That is simple. Build your Gates FIRST. THEN set the Poles to fit. Make the Hinges Heavy Duty so they don't give out over time. Make sure you Brace the Gate Post VERY well to avoid future Sagging. With the material you are using, You shouldn't have heat problems. If you build the gates to the opening, Make sure to allow for the Hinges (Whatever Type you choose) and you should be good. If you end up with more Gate than opening, It is the Tape Measures fault. You will not (or should not) have an issue with heat considering the material you are using. When you build it. Make sure you Tack it all together FIRST. DO NOT hard weld as you go. Once it is all fit up the way you want it. THEN weld out. When you start welding out, skip around. Do Not start at one end and weld to the other. Make sure you skip around in order to disperse the heat.
Parent - - By sparksandslag (**) Date 01-13-2014 03:05
Good points, Cactus.  I went and did one thing bassakwards---set the posts inside stone columns before we even thought about gating the opening.  That's what prompted the question.  So what you're saying is, given proper welding procedures, I shouldn't have any problem with the gates swelling  up to be too big for the opening.  I'll just be sure to leave plenty of gap where the gates meet.  Thanks for the input.
Parent - By welderbrent (*****) Date 01-13-2014 13:31
Cactus' view rings true with me as well.

On that short of a distance heating and cooling, thermal expansion, should not be an issue.  It will happen, but not in an amount that will effect your gates.  That is, as long as you have left any amount at all of space between the two gates and a proper hinge setup with the gap on that side. 

If you powder coat them it will be even safer as there is something about the coating that keeps the steel cooler.  Seems to protect from thermal conductivity so that it doesn't get as hot and thus does not expand as much.  Try it, put two pieces in the sun, one plain steel the other powdercoated, and leave them for a couple hours.  Then go put your hand on both pieces.  The coated will be noticeably cooler.  Especially with a lighter color.

Have a Great Day,  Brent
Parent - By kcd616 (***) Date 01-16-2014 20:09
quick tip
field weld your clasp or anchors to fit
how I have always done it
hope this helps
sincerely,
Kent
Parent - - By G.S.Crisi (****) Date 01-13-2014 15:14 Edited 01-13-2014 15:32
To answer your question.

For rough calculations, linear expansion of steel is 1 elevated to minus 5 power (i..e., 0.00001) meter per meter per degree Celsius of temperature difference. You may easily convert to foot per foot and degree F. 
For precise calculations, carbon, alloy and stainless steels have slightly different linear expansion coefficients, stainless being the higher and carbon the lower. Most engineering handbooks will tell you their value.

Giovanni S. Crisi
Sao Paulo - Brazil
Parent - - By eekpod (****) Date 01-14-2014 11:15
"if you end up with more gate than opening, it's the tape measures fault" :lol:
love it!!  that a keeper.
Parent - By welderbrent (*****) Date 01-14-2014 14:49
Yep, cut it three times and it's still too long.  Now if it were wood, it wood (intended) still be too short.  Just use your Brown's Gas and WELD it back together and start over.

Have a Great Day,  Brent
Parent - By Metarinka (****) Date 01-15-2014 20:09
I would cheat, build the gate a little less and then just put shims or washers behind the hinges. Likewise you can fit the finished gate then drill the holes for the hinges.

welding will cause distortion but it's usually angular not linear.  I.e it would want to bend the tubing more so than grow the overall length, that would require either thinning of the material or series tensile force.  If you measure you opening and make the cuts for your header and footer, I wouldn't count on them growing closer together after welding.
Parent - - By Ole Norm Date 01-15-2014 22:51
Not much to worry about s&s. At a 150 degree F. temperature variation, an 8 foot length of carbon steel will expand a little less than 1/8". That's .105" to be exact
Parent - By sparksandslag (**) Date 01-18-2014 22:08
Thanks to all of you for your input and advice.  All that will be taken into consideration when we build the gates.
Up Topic Welding Industry / General Welding Discussion / Steel expansion

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