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STRUCTURAL PIPE & TUBING

Common sizes for Bollards, Fencing, Piling, and Casing. From 2" OD to 24" OD.

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structural pipe and HSS tubing

Structural Pipe Specifications

Structural Pipe refers to steel pipe that is used for construction, load-bearing, or architectural purposes rather than for transporting fluids (Line Pipe).

Because it does not need to pass a pressure test, structural pipe is often the most cost-effective option for your project.

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Most Popular Structural Sizes

While we can source any diameter, these are the "standard" sizes kept in stock across the US for general construction.

A. Fence & Corral Sizes (Used Tubing)

Often sourced from the oilfield as "Used Oilfield Tubing." Ideal for cattle panels, H-braces, and perimeter fencing.

Common Name Actual O.D. Weight/Ft
2 3/8" 2.375" 4.60 lbs (approx)
2 7/8" 2.875" 6.40 lbs (approx)
3 1/2" 3.500" 9.20 lbs (approx)
B. Bollard & Post Sizes (Standard Pipe)

The industry standard for safety bollards (filled with concrete), sign posts, and parking lot barriers.

Nominal Size Actual O.D. Schedule 40 (Std) Schedule 80 (XH)
4" Pipe 4.500" .237" Wall .337" Wall
6" Pipe 6.625" .280" Wall .432" Wall
8" Pipe 8.625" .322" Wall .500" Wall
C. Structural Piling Sizes

Used for deep foundations, dock piles, and casing. Usually produced as Spiral Weld or ERW.

Nominal Size Actual O.D. Common Walls
10" Pipe 10.750" .365" / .500"
12" Pipe 12.750" .375" / .500"
16" Pipe 16.000" .375" / .500" / .625"
20" Pipe 20.000" .375" / .500" / .812"
24" Pipe 24.000" .375" / .500" / 1.000"

Sizing & Ordering FAQ

Nominal vs Actual: Pipe sizes up to 12" are "Nominal" (NPS), which roughly relates to the flow diameter inside. The Outside Diameter (OD) is always larger to accommodate the wall thickness. Therefore, a standard "2 inch" pipe will always measure exactly 2.375" OD on a tape measure.
Measurement System: PIPE is measured by its inner Nominal capacity (NPS) and Schedule (Wall). TUBING (whether Square, Rectangular, or Round) is measured by its exact Outside Diameter. A 2" Round Tube is exactly 2.000". A 2" Pipe is 2.375".
Wall Thickness: "Schedule" determines the thickness of the steel pipe wall. Schedule 40 is considered standard weight. Schedule 80 is "Extra Heavy" (a thicker wall). As the schedule number goes up, the outside diameter stays exactly the same, but the inside hole gets smaller.
21' or 42': Most new pipe is sold in Single Random Lengths (SRL ~ 21ft) or Double Random Lengths (DRL ~ 42ft). Piling pipe is often stocked in 60ft lengths. Used oilfield tubing usually comes in ~31ft joints.
Be Careful: "Structural Grade" usually implies the pipe was rejected for pressure use at the mill, or it is used material. If your project requires holding pressure, you should always specify ASTM A53 or API 5L prime, tested pipe.
In the used oilfield tubing market (commonly used for fencing), "Drifted" means a specialized mandrel has been passed through the pipe to ensure there are no dents or internal obstructions. This is a crucial step if you plan to insert smaller pipe inside of it later.
Black steel pipe is uncoated (aside from a mild mill varnish) and will rust if exposed to moisture. Galvanized pipe has been dipped in molten zinc to prevent corrosion, making it suitable for long-term outdoor use like handrails and fences.
No. In the used tubing world, people often round up in conversation. "2-7/8" is exactly 2.875" OD. "3-1/2" is exactly 3.500" OD. Always verify the exact decimal OD if you are buying caps, saddles, or clips.
The manual formula is: (OD - Wall Thickness) × Wall Thickness × 10.69. Or, you can save time and just use our free Pipe Weight Calculator.
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📏Structural Sizes›Bollard Pipe›Fence & Corral›Steel Casing›Piling (New & Used)›Square Tubing›
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Size Calculator

Need the precise OD and Wall Thickness for a specific pipe schedule?

Pipe Schedule Chart
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