ERW vs DOM - Go!
03-07-2012, 06:21 AM
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ERW vs DOM - Go!
First - Bitch bitch bitch - why risk your safety with ERW + bitch bitch bitch. Now there should be no reason to re-hash that thought. Car is a 200hp 3k lb lemons/chump racer, not a Brian SCCA workhorse.
Fact is, its cheap and a little birdy has informed me cage material is about to sky rocket. DOM cage = $730, ERW cage = $320, price of car was $100. Has anyone seen an ERW tube failure in a roll cage? General consensus seems to be that welds / failure to reinforce mount points w/ spreader plates is a larger risk than tubing selection. Basically, a properly built ERW cage > Improperly built DOM cage. I want to know how many people have seen a failure that has been DIRECTLY linked to being ERW and not DOM. Min for the cage is 1.75 x .095. If I went DOM that would be the size, I'd go up in wall thickness to .120 if it was ERW. Also, anyone have any 1.75x.095 DOM or 1.75 x .120 ERW they wanna sell for the cheap? Sponsorship available
To prove the point, here's a mustang on its roof.
Note the DOM tubing coming through the improperly reinforced floor pans.
Fact is, its cheap and a little birdy has informed me cage material is about to sky rocket. DOM cage = $730, ERW cage = $320, price of car was $100. Has anyone seen an ERW tube failure in a roll cage? General consensus seems to be that welds / failure to reinforce mount points w/ spreader plates is a larger risk than tubing selection. Basically, a properly built ERW cage > Improperly built DOM cage. I want to know how many people have seen a failure that has been DIRECTLY linked to being ERW and not DOM. Min for the cage is 1.75 x .095. If I went DOM that would be the size, I'd go up in wall thickness to .120 if it was ERW. Also, anyone have any 1.75x.095 DOM or 1.75 x .120 ERW they wanna sell for the cheap? Sponsorship available
To prove the point, here's a mustang on its roof.
Note the DOM tubing coming through the improperly reinforced floor pans.
Last edited by RandomTask; 03-07-2012 at 06:29 AM.
03-07-2012, 08:58 AM
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Re: ERW vs DOM - Go!
Yes, the problem is the floor pan reinforcement and not the tubing in the case of that picture. But you really are just saying things that are common sense. If you have a poorly designed or poorly fabricated cage, it doesn't matter what material it's made of. If it's properly designed and fab'd, then you can take advantage of better materials if the budget allows and the need is there. Or if the rules specify the materials, design envelope, and tubing dimensions.
What was the question?
What was the question?
03-07-2012, 09:39 AM
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Fitty Tuckin
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Re: ERW vs DOM - Go!
Taken from a site I frequent concerning 4x4 cage design
Right...I'll try to keep this tight and focused for ya!
DOM, ERW, HREW...all types of "mechanical tubing", as opposed to pipe. All mechanical tubing is dimensioned by OD and a wall thickness.
DOM is actually not a type of tubing, but a process that is applied to tubing after it is initially constructed. It is Drawn Over a Mandrel...which "cold works" it, giving more exact dimensions, smoother finich, and better allignment of the crystal latice structure. It is NOt seamless tubing, and it started life as some sort of EW (electric welded) tubing. Most commonly, when people say "DOM" they mean 1020 mild carbon steel rolled electric welded tubing that is then drawn over a mandrel.
Other mechanical tubing that is not necessarily drawn over a mandrel can be either hot or cold rolled (i.e. rolled from a flat strip into a tube when either hot or cold) and most commonly available will then be electric resistance welded to form the final tube.
Generally...cold forming and cold working add strength and uniformity to a product, and reduce stress.
So VERY BASICALLY, in terms of strength you usually have, in order:
DOM
CREW (cold rolled electric welded)
HREW (Hot....)
Again...these are all just processes, to fully call out the materil, you need to specify the type of steel...but most commonly we are talking about either 1020 mild carbon steel, or 4130 or 4140 Chromium molybdenum alloy steel or 4340 nickel chromium molybdenum alloy steel.
DOM, ERW, HREW...all types of "mechanical tubing", as opposed to pipe. All mechanical tubing is dimensioned by OD and a wall thickness.
DOM is actually not a type of tubing, but a process that is applied to tubing after it is initially constructed. It is Drawn Over a Mandrel...which "cold works" it, giving more exact dimensions, smoother finich, and better allignment of the crystal latice structure. It is NOt seamless tubing, and it started life as some sort of EW (electric welded) tubing. Most commonly, when people say "DOM" they mean 1020 mild carbon steel rolled electric welded tubing that is then drawn over a mandrel.
Other mechanical tubing that is not necessarily drawn over a mandrel can be either hot or cold rolled (i.e. rolled from a flat strip into a tube when either hot or cold) and most commonly available will then be electric resistance welded to form the final tube.
Generally...cold forming and cold working add strength and uniformity to a product, and reduce stress.
So VERY BASICALLY, in terms of strength you usually have, in order:
DOM
CREW (cold rolled electric welded)
HREW (Hot....)
Again...these are all just processes, to fully call out the materil, you need to specify the type of steel...but most commonly we are talking about either 1020 mild carbon steel, or 4130 or 4140 Chromium molybdenum alloy steel or 4340 nickel chromium molybdenum alloy steel.
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