Tube vs. Pipe

[Rich]

my personal opinion is that design, bends, and welds determine strength more than dom vs hrew vs pipe

It's more than an opinion... that's a fact!

 

[drkelly]

I am building my exo-cage out of pipe. I was able to get 150 ft of it for $30 from a place about 20 minutes from where I live. I also traded a couple of old lockouts to go half in with a buddy on a HF pipe bender. Depending on the diameter and wall thickness, it can kink and wrinkle on the inside of the bend. It can also flatten the outside slightly. I am still in the building process with my cage, but am reasonably satisfied with the outcome. My friends cage is pipe, and it has held up to some fairly hard abuse. I think for a trail vehicle, proper design is probably more important than material choice. Oh yeah, I am an engineer, and am obviously building my cage out of pipe.

 

[SpydyrWyr]

Yeah, my good friend Yotaman built his exo out of pipe. He got some kinking and some deflection, but it's pretty stout so far. He's added some bracing and other load bearing members, but it's done pretty well from what we've seen. Yeah, this is in the driveway and done on purpose... we took turns flopping it.

 

[HardTaco]

Steves is properly braced (wasnt done in the picture yet).....and his pipe has def. stood up to a tremendous beating. (we witnessed it last weekend). I think you will be fine with pipe Dan....Im no NCSU engineer or honda salesman.....but i would feel safe using pipe on a properly built exo.


my worthless .02

Josh

 

[paulevans76]

I have a cheapo pipe bender and you just have go slow, set your dies in the right holes, make sure you got grease where you need it, and don't go beyond the max angle. The hardest thing is putting multiple bends on the same plane.

 

[SpydyrWyr]

.....I'm no NCSU engineer or honda salesman.....

Well Josh you may not be either of those things, but your still my hero ... and your .02 is most certainly not worthless to me.

 

[Wolfpack OffRoad]

I have a cheapo pipe bender and you just have go slow, set your dies in the right holes, make sure you got grease where you need it, and don't go beyond the max angle. The hardest thing is putting multiple bends on the same plane.

Go with JD squared. Very good stuff. We use the model 3 I think. Works flawless. (wish I could say the same thing about the operators).

http://www.jd2.com/

 

[Rob]

I have the JD2, good bender, but I would go with the pro-tools one. Better customer service. Took me 2 months to get a replacment follower die from jd2.

 

[rockcity]

What Rufus just said - x2

And another 2¢ - (And I know I am gonna catch hell for saying this) HREW is fine for most other stuff, cages etc.

For the ones that says nothing less than DOM is acceptable for a cage -

Then why stop there - go straight to moly.

Seriously - it's your backside. Overbuilt is not a bad thing.
If you feel better with all DOM (and can afford it) by all means use it.

I feel much, much better with my all DOM buggy. I don't use anything except DOM for anything that protects passengers. I've even used it on rock sliders and bumpers, cause its what I had. But, I'm not using anything but DOM on the cage, etc....


Rob

 

[rockcity]

correct on the pipe being ok. But, if you want something that is lighter, I'd use tube.


And BTW, NASCAR doesn't approve pipe for the chassis

 

[Ridgerunner]

please just look this up w/ the search feature. it has been covered here and every other 4x4 forum on the internet.

Funny,

I read this forum all the time and I have rarely seen this subject cover. I am sure it has been beat to death on pirate. But since I can not stand that site with all of the a$$'s on there I really could careless what infomation is there. I am not that desparate.

Good question though

 

[SpydyrWyr]

correct on the pipe being ok. But, if you want something that is lighter, I'd use tube.


And BTW, NASCAR doesn't approve pipe for the chassis

Isn't there also a minimum wall thickness of 1/8" wall for most racing apps?

 

[SpydyrWyr]

Wow, I just found some pretty good information. A lot of it I'm sure most everyone knows, but this is pretty comprehensive. Thanks to Old Scout via Pirate, found it through a GlobalSpec search.....

Here is some valuable information dealing with types of Tubing, including structures, specifications, applications, size ranges, and chemical analysis.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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 finish, and better alignment 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 material, 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.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ROPS (ROLL-OVER PROTECTIVE STRUCTURE) TUBE
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Structural tubing that offers high strength-to-weight ratio and a higher impact toughness. The steel is fully killed and melted to fine grain practice. Customers may specify yield, tensile, elongation and charpy impact values according to their needs. This product is to minimize the probability of catastrophic failure of vehicle cab structures in the event of a roll-over accident.
American Specifications: ASTM A500 for dimensional tolerance, squareness, straightness, twist and corner radii. Mechanical properties can vary by end user.

Applications: Cabs for agricultural vehicles, road and off-road construction equipment, and lift trucks.

Size Range: 2" - 12" (50 mm - 305 mm) sq and the standard rectangle sections of the same perimeters. Rounds available as special inquiries.


Typical Chemical Analysis: Alloying elements may be added to achieve mechanical property requirements.
C .22 max
P .04 max
Mn 1.65 max
S .05 max
Typical Mechanical Properties: Can vary to customer specification
Tensile strength (ksi) 70 min
Yield point (ksi) 50 min
Elongation (% in 2") 20 min
Charpy impact Wall Ft/lb (min) Temp (°F)
3/16" 11.0 -20
1/4" 13.0 -20
3/8" 18.0 -20




Machinability: Good

Weldability: Excellent

Testing: Generally one tensile test and one set of three impact tests are taken from each lot of tubing. Tubing is tested in accordance with the latest revision of ASTM A370. Certification of material is available.

Materials Resource Page Number: 41

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1020 DOM STEEL TUBE

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1020 is normally used in the manufacturing of small-diameter or thin-wall DOM steel tube. DOM is formed from strip and electric-resistance welded, then cold drawn to size. The cold drawing process causes the weld line to virtually disappear.
American Specifications: ASTM A513 Type 5

British Specifications: 040 A 20, 070 M 20

Applications: Mechanical, hydraulic cylinders, shaft, tight tolerance requirements

Size Range: 1/4" - 14&1/2" (6 mm - 368 mm) OD; .035" - .625" (.9 mm - 16 mm) wall

Typical Chemical Analysis: C .15-.25
Mn .30-.60
P .040 max
S .050 max

--------------------------------------------------------------------------------
Typical Mechanical Properties: Tensile strength (ksi) 80
Yield point (ksi) 70
Elongation (% in 2") 15
Rockwell hardness RB80



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1018 COLD DRAWN AND HOT FINISHED SEAMLESS TUBE
--------------------------------------------------------------------------------
1018 is normally used in the manufacturing of cold drawn and hot finished seamless tube. The production of seamless tube is generally made by piercing a hot rolled bar. Hot finished is generally furnished in the unannealed condition, whereas cold drawn seamless is supplied in the unannealed or S/R annealed conditions, depending on the size.
American Specifications: ASTM A519

British Specifications: 070 M 20, 080 A 15

Applications: Axles, shafts, gears, bearings

Size Range: 1/8" - 24" (3 mm - 610 mm) OD; .0218" - 3.00" (.6 mm - 76 mm) wall

Typical Chemical Analysis: C .15-.20
Mn .60-.90
P .040 max
S .050 max
Typical Mechanical Properties: CDS HFS
Tensile strength (ksi) 80 60
Yield point (ksi) 60 35
Elongation (% in 2") 15 30
Rockwell hardness RB88 RB60



--------------------------------------------------------------------------------


1010 ELECTRIC WELD STEEL TUBE


--------------------------------------------------------------------------------

1010 is normally used in the manufacturing of electric-resistance welded tube. The product is available normally in cold rolled strip (16 gauge and lighter), and hot rolled strip (.083" wall and heavier). The product can be obtained in the as-welded condition (flash-in) or in the flash-controlled condition.

American Specifications: ASTM A513 Type 1 and Type 2

British Specifications: 040 A 10, 045 A 10

Applications: Machinery stands, exhaust tubes, handles, hand rails, display stands, conveyor rollers

Size Range: 1/4" - 10" (6 mm - 254 mm) OD; .028" - .375" (.7 mm - 10 mm) wall

Typical Chemical Analysis: C .08-.13
Mn .30-.60
P .035 max
S .035 max
Typical Mechanical Properties: Tensile strength (ksi) 45
Yield point (ksi) 32
Elongation (% in 2") 15 min
Rockwell hardness RB55 min





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1026 STEEL TUBE


--------------------------------------------------------------------------------

1026 grade is normally used in the manufacturing of DOM, cold drawn seamless and hot finished seamless. This grade normally furnished over 2" OD, with walls heavier than .156". A variety of thermal treatments can be supplied, depending on the type and size of material.

American Specifications: ASTM A519 (SMLS), ASTM A513 Type 5 (DOM)

British Specifications: 070 M 26

Applications: Mechanical, hydraulic cylinders, shaft, tight tolerance requirements

Size Range: 1/8" - 24" (3 mm - 610 mm) OD; .028" - 3.00" (.7 mm - 76 mm) wall

Typical Chemical Analysis: C .22-.28
Mn .60-.90
P .040 max
S .050 max
Typical Mechanical Properties: CDS DOM HFS
Tensile strength (ksi) 87 80 70
Yield point (ksi) 72 70 47
Elongation (% in 2") 10 10 28
Rockwell hardness RB89 RB85 RB78

 

[krehel24]

correct on the pipe being ok. But, if you want something that is lighter, I'd use tube.


And BTW, NASCAR doesn't approve pipe for the chassis

MMMM....I thought this was a 4x4 site, not a race car site well its ok it's been a long time since I rolled my rig at 200mph on the trail thank God for that DOM, if I had PIPE I may have DIED!!

 

[Rich]

And if you want something to stand up to repeated abuse without cutting out bent tubes every time you go out, you need to build it tougher. Take your pick - 200mph 1 time, or 1mph 200 times.

 

[rockcity]

Isn't there also a minimum wall thickness of 1/8" wall for most racing apps?

I think, but I'm not sure. I"m not up to date on the rules. They do use DOM because it is much more consistent on wall thickness and the builders can go with the minimum required to save weight and still be in the rules

Well, I know I'd rather be inside my DOM cage than in a pipe cage, not just for safety, but weight savings as well.

Rob

 

[maverick]

True. But your first statement is very odd.

ive been around cages on dirt track cars an jeeps half my life , due to vibration an body roll DOM will crack period, ive seen it counless times.
take my word for it or not will not change the fact. the stuff is to hard,
hardness equals brittle. However this could, an im not ruling it out, could have been due to the grade of DOM being used.

 

[faTJeeper]

"Generally...cold forming and cold working add strength and uniformity to a product, and reduce stress."

This statement is simply not true. cold working adds to strength by causing the molecules to not be uniform so that they basically get all jumbled up and have a hard time moving past each other. this makes the metal stronger in terms of yield strength, but it in fact causes internal stress within the metal making it more brittle and prone to cracking rather than simply deforming. i do not have an engineering degree but i have an A.A.S. degree in mech. eng. technology and did go to state for three years in the Mech. Eng. program

 

[braxton357]

The uniformity isn't referring to the molecular structure, it's referring to the actual tube itself. Hrew tubing varies quite a bit in wall thickness which is why when you see kit cages for cars, they're .134 wall because the sfi limit is .118 and hrew can vary more than that. I know that what your theory is telling you about cracking rather than bending, but 1, before either cracking *or* bending, it will take far more abuse than pipe or hrew. And 2, I've seen plenty of dom turned into a pretzel. It's not like it's a piece of lumber, it will bend long before breaking. It's also pretty well known that it will dent easier than pipe because of a, toughness..and b. pipe is typically thicker.


General concensus is this, hrew is just fine for a cage..as long as it's a true cage. Pipe (astm 53) too will work for a off road cage--and has been proven literally thousands of times over the past 40 years, and there are a *lot* more pipe cages running around than people are willing to admit...plus lets not forget that 1.5" pipe is actually 1.9" dia and .150 wall, and it too will bend and deform long before yielding. I've seen this happen too. The main problem with pipe is the fact that 1.5" pipe is so much heavier than 1.5x.120 hrew or dom..and all of that weight is above the CoG. Dom is a proven material also, that is used in most high end race car and offroad chassis'...most people that use dom don't care about long term fatigue since they've got enough money to replace it, same with crmo.

Which brings us back to what the lowly honda salesman said ( )...you're an engineer, it's your life that's on the line. Look up the facts for yourself rather than relying on internet knowitalls, then model your cage after what's known to work and build it. Pretty simple really.

 

[rockcity]

for all ya tube haters, thats fine, I'll keep the DOM...

 

[cj7jakfitch]

I work with pipe every day. Pipe is really strong and can withstand alot. The main problem with pipe over tubing is that pipe will break and crack near the weld after it is pushed or bent so far. Tubing will bend and it absorbs more. Also people talk about how pipe is sized. When you take a piece of 2" pipe and measure it you will not find 2" no where on it. That goes for pipe from 1/8" to 12" and any sch. The only pipe that measures what it says is 14" so far that we use at work. I can get pipe free all day log but every cage I've done has been DOM tubing with .120 wall (11 guage). Its my life or one of my friends life the cage will be protecting.

 

[Rich]

for all ya tube haters, thats fine, I'll keep the DOM...

I'm with you, man..

Here's a thought - maybe all the pipe usage will raise the price of pipe, and lower DOM again? (A guy can dream, can't he?)

 

[braxton357]

Uppity-assed caviar eating DOM users.

 

[rockcity]

Hey, my life (or anyone else's) isn't worth a few dollars saved using pipe, regardless of how much many others have used it and its held or what-not.

Rob

 

[braxton357]

Then why not spend the extra couple dollars per foot and go with 4130 instead of *comparitively* weak DOM ?