Mild steel cage material.

Jim Hughes · 05-27-2015, 11:35 PM

We are using mild steel tubing in a Super Gas car.

We need to buy a few more sticks of tubing.

The roll cage material currently is 1 5/8" EWS. from S&W.

Can we use DOM with the EWS material?

What is the real difference between the two materials?

Thank You for the help.

Bill Baer · 05-28-2015, 09:37 AM

DOM is DRAWN OVER MANDREL so there is no seam line inside of the tubing. EWS is just standard mild steel tubing the only advantage of the DOM is the more exact Inner diameter. DOM is more expensive than EWS.
I Personally would give S&W call and ask them.
Since your roll cage will be ultra sonic thickness tested, I would consider going up one wall thickness size from the minimum required.
Tubing as manufactured has a tolerance .120 wall tubing may be .118-.122 an it can get even thinner on the outside of a bend.
While slightly thicker tubing is a little heavyer it can be a huge PITA to change out a tube in a completed roll cage.

SG192L · 05-28-2015, 08:55 PM

If you can tig weld the cage for the same amount of money you can use 4130 chromoley an you will not add as much weight.

Tom Goldman · 05-28-2015, 09:09 PM

DOM currently runs almost the same price as Chromemoly.
The problem with DOM is the NHRA .118" min spec does not allow for the inconsistency that occurs in wall thickness.
I've had some check as thin as .116 ,Thats why the chassis shops prefer to sell you ERW .134 wall, it will always pass.
IF you have a TIG , I'd use .083 moly . It is permissable to mix mild and moly, but it must be TIG'd.
Always a good idea to save a sample for the chassis inspector to compare to when mixing any of the above.

05-27-2015, 11:35 PM	#1
Jim Hughes Junior Member Join Date: Oct 2004 Posts: 31 Likes: 0 Liked 0 Times in 0 Posts	Mild steel cage material. We are using mild steel tubing in a Super Gas car. We need to buy a few more sticks of tubing. The roll cage material currently is 1 5/8" EWS. from S&W. Can we use DOM with the EWS material? What is the real difference between the two materials? Thank You for the help.

05-28-2015, 09:37 AM	#2
Bill Baer Senior Member Join Date: Jul 2007 Location: Nothern IL Posts: 596 Likes: 1 Liked 1 Time in 1 Post	Re: Mild steel cage material. DOM is DRAWN OVER MANDREL so there is no seam line inside of the tubing. EWS is just standard mild steel tubing the only advantage of the DOM is the more exact Inner diameter. DOM is more expensive than EWS. I Personally would give S&W call and ask them. Since your roll cage will be ultra sonic thickness tested, I would consider going up one wall thickness size from the minimum required. Tubing as manufactured has a tolerance .120 wall tubing may be .118-.122 an it can get even thinner on the outside of a bend. While slightly thicker tubing is a little heavyer it can be a huge PITA to change out a tube in a completed roll cage. __________________ Bill Baer 3391 SC, 339B SC, QR

05-28-2015, 08:55 PM	#3
SG192L Junior Member Join Date: Dec 2012 Posts: 14 Likes: 0 Liked 0 Times in 0 Posts	Re: Mild steel cage material. If you can tig weld the cage for the same amount of money you can use 4130 chromoley an you will not add as much weight.

05-28-2015, 09:09 PM	#4
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,436 Likes: 776 Liked 700 Times in 204 Posts	Re: Mild steel cage material. DOM currently runs almost the same price as Chromemoly. The problem with DOM is the NHRA .118" min spec does not allow for the inconsistency that occurs in wall thickness. I've had some check as thin as .116 ,Thats why the chassis shops prefer to sell you ERW .134 wall, it will always pass. IF you have a TIG , I'd use .083 moly . It is permissable to mix mild and moly, but it must be TIG'd. Always a good idea to save a sample for the chassis inspector to compare to when mixing any of the above. __________________ Tom Goldman 1500 SG , 1506 STK