Square and Rectangular Tube
Welded square tube from 1-1/2 x 1-1/2 to 6 x 6 and rectangular from 2 x 1 to 10 x 2, with every size between, to ASTM A500 or A513.
Flat sides weld flat.
That is why trailer rails, rack uprights and machine frames start with square and rectangular tube.
What It Becomes.
Square and rectangular tube welds flat to flat, so it is the first choice for frames.
- Trailer frames and crossmembers
- Implement frames and toolbars
- Pallet and storage racks
- Solar racking rails
- Truck bed and body frames
- Gates, canopies and light framing
- Furniture and fitness frames
- Carts and conveyor frames
How to Pick a Size and Wall.
On a structural part, an engineer sets the size and wall from the load. On a mechanical part, fit, finish and weight usually decide. Either way, a few rules hold for every square and rectangle.
Size Before Wall
Stiffness comes mostly from how far the steel sits from the center. For the same weight per foot, a larger tube with a thinner wall is usually stiffer than a smaller tube with a heavier wall. A thin wall dents more easily and is easier to burn through when welding, so the lightest wall is not always the right one.
Stand Rectangles on Edge
A rectangle is much stiffer bending across its long side than across its short side. A 4 x 2 set on edge, with the 4 in side vertical, carries far more than the same tube laid flat, which is why trailer and rack beams are rectangles standing up.
Check the Numbers
Section modulus sets bending strength, moment of inertia sets deflection, and weight per foot sets cost and freight. The section properties calculator gives all three for every size and wall on our list, both ways up.
Mill Lengths and Bundles.
- Mill Lengths
- 20 to 48 ftStandard bundles are 20, 24 and 40 feet, with clean cold-saw ends.
- Pieces per Bundle
- 50 / 352 x 2 at 20 or 24 feet, and 4 x 2 x .120 at 24 feet (about 3,850 lb). Smaller bundles are available to suit your crane or forklift.
- Least Waste
- Check the DropA 7 ft part gives 2 pieces and a 6 ft drop from 20 ft, but 3 pieces and a 3 ft drop from 24 ft.
- Truckload
- Weight FirstA flatbed load is limited by weight more than space. The bundle planner gives pieces, layout and weight per bundle and per load.
Questions.
Have a drawing with a size or wall that isn't listed? Ask; the list is what the mill runs most.
What sizes of square tube do you make?
Square tube from 1-1/2 x 1-1/2 to 6 x 6. The standard list, with weights, is 2, 2-1/2, 3, 3-1/2 and 4 inch in walls from .083 (14 gauge) to .188 (3/16 inch); ask us for the sizes outside it.
What sizes of rectangular tube do you make?
Rectangles from 2 x 1 to 10 x 2 and the sizes between. The standard list is 2-1/2 x 1-1/2, 3 x 1, 3 x 1-1/2, 3 x 2, 4 x 2, 4 x 3, 5 x 2, 5 x 3 and 6 x 2, in the same walls as the squares.
What lengths are available?
Standard bundles are 20, 24 and 40 feet. We run mill lengths from 20 to 48 feet, and we can cut to your length.
Is it A500 Grade B or Grade C?
Our structural tube is made to the chemical and mechanical requirements of ASTM A500 Grade B and Grade C. Mechanical tube is made to ASTM A513 Type 1 and Type 2, grades 1010 to 1020 unless you specify otherwise.
Where is the weld seam?
On a flat side. On rectangles it is usually on a long side, and on the short side on request. The outside weld flash is always removed, and every weld is eddy current tested in line.
What is the difference between A500 and A513 square tube?
A500 is structural tube with a guaranteed minimum yield, 50,000 psi for Grade C in square and rectangle. A513 is mechanical tube, ordered by size, wall and finish, with a closer outside size tolerance. A500 vs. A513 compares them side by side.
How much does 2 x 2 square tube weigh per foot?
In A500, 2 x 2 weighs 2.105 lb/ft in .083 wall, 2.944 lb/ft in .120 wall and 4.327 lb/ft in .188 wall. The tube weight calculator gives any size, wall and length.
Is rectangular tube stronger on edge or flat?
On edge. A rectangle bending across its long side is much stiffer and stronger than the same tube laid flat. The section properties calculator shows both directions for each size.
What do I need to send for a quote?
The size and wall, the spec and finish, the length (mill length, or your cut length and tolerance), the quantity per order or per year, and where it ships. The quote form asks for each one. Give the size long side first, and the wall as a decimal; gauge tables differ between tube and sheet.
Technical Data.
Sizes and weights, specifications and tolerances.
Sizes and Weights.
Pounds per foot for every size and wall on our standard list. Pick a number to open it in the size finder. We make squares from 1-1/2 to 6 inch and rectangles from 2 x 1 to 10 x 2; ask us for a size that is not listed.
Sizes in inches. A dash means not on the standard list in that wall; ask us.
Rectangles with the same perimeter as a square weigh the same: a 3 x 1 and a 2-1/2 x 1-1/2 are both cut from the same strip as a 2 x 2.
Which Specification to Order.
Structural tube carries loads in buildings and frames and is ordered by strength. Mechanical tube is ordered by size and finish for parts you cut, bend and weld.
ASTM A500
Structural tubing. Grade C is the common choice, and most tube is dual-certified to Grades B and C.
- Grade B yield
- 46,000 psi min.
- Grade C yield
- 50,000 psi min.
- Tensile
- 58,000 / 62,000 psi
ASTM A513
Mechanical tubing, as-welded from hot rolled (Type 1a) or pickled and oiled (Type 1b) steel. Tighter size tolerances than A500.
- Ordered by
- Size, wall, finish
- Strength
- Set by the steel grade
ASTM A787
Mechanical tubing made from galvanized steel, for tube that is welded into outdoor products without being painted.
- Coating
- Zinc, from the coil
- Used for
- Fence, racking, trailers
What the Spec Allows.
Unless an order says otherwise, tube is made to the ASTM tolerances for the spec ordered. These are the figures on our A500 and A513 data sheets for square and rectangular tube.
A500 Structural
- Outside size
- ±.020 to ±.030 in by largest side to 5-1/2 in; 1% over
- Wall
- ±10% of nominal
- Corner radius
- Up to 3 times the wall
- Squareness
- 90° ±2°
- Twist
- .062 to .087 in in 3 ft
- Straightness
- .025 in times the length in feet
A513 Mechanical
- Outside size
- ±.008 to ±.020 in by widest side to 4 in; ±.030 on 5 x 2 and 5 x 3, ±.036 on 6 x 2
- Wall
- ±10% of nominal
- Squareness
- .006 in per inch across flats
- Twist
- .062 to .087 in in 3 ft
- Straightness
- 1/16 in in 3 ft
A500 or A513?
Order A500 when the tube carries a load an engineer calculated, since A500 promises a minimum yield. Order A513 when the part has to fit a cap, a bracket or a fixture, since A513 holds the outside size closer. A513 squares are also listed a little heavier per foot, mostly because their corners are tighter.
Tell Us the Size,
Wall and Footage.
One size or a whole program, in mill lengths or cut to your length. The quote form takes about two minutes.