Schedule 40 4130 Tubing
Schedule 40 is the standard-weight pipe wall and the schedule most often quoted by mistake for tubing. Pipe sizes are nominal, so the numbers on the drawing are not the dimensions of the material.
What Schedule 40 Means in Pipe
In the NPS pipe system, Schedule 40 specifies a wall thickness that varies with nominal pipe size. For example, 1" NPS Schedule 40 has OD 1.315" and wall 0.133"; 2" NPS Schedule 40 has OD 2.375" and wall 0.154". These OD values are the actual dimensions used in the pipe system — not the nominal size.
For 4130 mechanical tubing: if the intent is a 4130 tube with dimensions similar to a specific NPS Schedule 40 pipe, the buyer should specify the actual OD and wall (taken from a pipe data table) rather than the schedule designation.
| NPS Schedule 40 Size | Actual OD | Wall (approx.) |
|---|---|---|
| 0.5" NPS Sch 40 | 0.840" | 0.109" |
| 0.75" NPS Sch 40 | 1.050" | 0.113" |
| 1" NPS Sch 40 | 1.315" | 0.133" |
| 1.5" NPS Sch 40 | 1.900" | 0.145" |
| 2" NPS Sch 40 | 2.375" | 0.154" |
| Note | Convert to actual OD × wall for 4130 CDS specification |
Schedule 40 Dimensions by Pipe Size
The nominal size is a name; the outside diameter is larger than the name for every size below 14 inch. The table lists the real dimensions.
| Nominal pipe size | Outside diameter | Schedule 40 wall |
|---|---|---|
| 1/2" | 0.840" (21.3 mm) | 0.109" (2.77 mm) |
| 3/4" | 1.050" (26.7 mm) | 0.113" (2.87 mm) |
| 1" | 1.315" (33.4 mm) | 0.133" (3.38 mm) |
| 1-1/2" | 1.900" (48.3 mm) | 0.145" (3.68 mm) |
| 2" | 2.375" (60.3 mm) | 0.154" (3.91 mm) |
| 3" | 3.500" (88.9 mm) | 0.216" (5.49 mm) |
| 4" | 4.500" (114.3 mm) | 0.237" (6.02 mm) |
A request for "1-1/2 inch Schedule 40 in 4130" therefore means a tube of about 1.900" OD with a 0.145" wall. 4130 mechanical tube is made in tube sizes such as 1.875" or 2.000", so the nearest available size has to be agreed. Walls for the lighter and heavier series are on the Schedule 10 and Schedule 80 pages.
Frequently Asked Questions
Can I substitute 4130 CDS for Schedule 40 pipe in a pressure application?
Not automatically. Pipe and mechanical tube are different product forms with different governing standards. A formal engineering substitution assessment is required, and the responsible pressure system engineer must confirm acceptability under the applicable pressure code.
What size is 1-inch Schedule 40 pipe really?
1.315" outside diameter with a 0.133" wall, giving a bore of about 1.049".
Why is 4130 not sold in pipe schedules?
4130 is supplied as mechanical tubing to ASTM A519, which is dimensioned by actual OD and wall. Pipe schedules belong to piping standards.
How do I convert a Schedule 40 size to a tube size?
Look up the actual OD and wall of the pipe size, then ask for the nearest tube OD and wall.
Convert Schedule 40 to 4130 Mechanical Tube
Identify the actual OD and wall for your NPS Schedule 40 size, then provide for a 4130 CDS quotation.
- Actual OD (converted from NPS)
- Wall
- Standard
- Footage
- Application
- MTC
- Delivery