Bollard Pipe and Cover Size
Understanding Names and Sizes
At first glance, Bollard Pipe and Cover Size can be confusing. But, once you understand how the “naming” works, it will all become clear.
First, read what the BOSS says, and that might be enough to understand.
Then study the Bollard Pipe and Cover Size Chart.
Then, if you have time, you can read the explanations about Bollard Pipe and Cover Size.
The BOSS says…
Look. A 6″ Bollard Cover covers a 6″ Pipe. It doesn’t mean the cover is 6″ across. And a 6″ Pipe is 6″ on the inside. The outside is like 6 5/8″. Still, the 6″ Bollard Cover covers the 6″ Pipe because the 6″ Bollard Cover is like 7″ on the inside. It’s only called 6″ because that’s the pipe it’s for. Capische?
Bollard Pipe and Cover Size Chart
<- On Small Screens, Scroll Chart Sideways ->
ID: Inner Diameter
OD: Outer Diameter
| Bollard Pipe Links | Pipe ID 40/80 | Pipe OD | Pipe Circumference | Bollard Cover Links | Cover ID |
| 4 inch SCH 40 or 80 | 4.026"/3.826" | 4 1/2" | 14 1/8″ | 4 inch | ~5" |
| 5 inch SCH 40 or 80 | 5.047"/4.913" | 5 9/16" | 17 15/32″ | 5 inch | ~6" |
| 6 inch SCH 40 or 80 | 6.065"/5.761" | 6 5/8" | 20 13/16″ | 6 inch | ~7" |
| 8 inch SCH 40 or 80 | 7.981"/7.625" | 8 5/8" | 27 3/32″ | 8 inch | ~9" |
| 10 inch SCH 40 | 10.02" | 10 3/4" | 33 25/32″ | 10 inch | ~11" |
| 12 inch Standard | 12.0" | 12 3/4" | 40 1/16″ | 12 inch | ~13" |
Quick Explanation of Pipe and Cover Sizes
For this example, we’ll use 6″ Schedule 40 Pipe.
The 6″ Schedule 40 Pipe has a about a 6″ inner diameter which explains it’s name because pipes are used to move fluids, so it’s the interior volume of the pipe a plumber would like to know. The 6″ Schedule 80 has a thicker wall, but the same outer diameter (so you need not worry), so the inner diameter is a bit smaller that Schedule 40. The Schedule 40 of any pipe (4″, 6″, 8″ etc.) typically has an interior diameter that matches the name of the pipe. Other schedules (wall thickness) vary from that basis, keeping the outer diameter consistent; in this case, all 6″ Pipe ODs are 6 5/8″ regardless of schedule.
This “6 inch” pipe has a 6 5/8″ outer diameter. What is known as a “6 inch Bollard Cover” is designed to cover a 6 inch pipe which has the 6 5/8″ outer diameter. Hence, the cover has more like a 7″ inner diameter and maybe a 7.5″ outer diameter, but it’s called six inch because its name is tied to what it’s covering, not its dimensions.
Steel Pipe vs Steel Round Tube
In the world of steel, there is pipe and there is round tube. Steel Pipe is usually used for moving fluids while Steel Tube is generally used for structural applications. Since Steel Pipe deals with fluid pressure, Pipe tends to have thicker walls, and that’s why it is used for bollards. Incidentally, tube has rectangular, square and round, where as pipe is always round.
Diameters and Wall Thickness
In the world of pipe and round tube, there is:
- Inner Diameter (ID)
- Outer Diameter (OD)
- Wall Thickness which equals 1/2 x (OD – ID). 1/2 because OD – ID leaves two walls as the remainder.
Nominal
Nominal means “by name only”. When you buy wood 2×4 studs, you know they are actually 1.5″ x 3.5″. The 2×4 name is the product’s “nominal” name.
Pipe Nominal Name
The pipe name, like 6 inch or 8 inch refers to it’s inner diameter (ID) because pipes function to move fluids, so the ID is more important. Thus, a 6″ Pipe is actually referring (sometimes loosely) to it’s ID. The OD might be 6 5/8″. That’s in contrast to tube, where a 6″ tube is 6″ OD because you are building with it, so the outer dimensions are of greater concern.
Pipe Schedule
Pipe typically has a “Schedule” like 10, 40 or 80, for instance. The Schedule Number refers to how “heavy” the wall is, not an precise thickness. A Schedule 40 6″ Pipe and a Schedule 40 8″ Pipe have different wall thicknesses. A Pipe Schedule is like a ratio of the wall thickness to it’s diameter.
