14 Inch NB 4130 Tubing
"14 inch NB" is a pipe term, not a tube size. Nominal bore describes a pipe series by name, and at 14 inches and above the name equals the outside diameter, so 14" NB pipe measures 14.000" (355.6 mm) OD.
Pipe vs. Tube Sizing
This distinction is fundamental in industrial procurement:
- Pipe (NPS/NB system): Sized by nominal bore. A 14" NPS pipe has an OD of 14.000" — but for smaller NPS sizes, the OD does not correspond to the NB at all (e.g., 1" NPS pipe has OD of 1.315").
- Mechanical tubing (4130 CDS): Sized by actual OD and wall in decimal inches or millimetres. There is no 'nominal bore' designation.
4130 chromoly CDS tubing is a mechanical tube product — it is specified by OD and wall, not by NB/NPS. If you are looking for a large-diameter 4130 tube, specify the required actual OD (in inches or mm) and wall.
| Sizing System | Designation | 4130 CDS Application |
|---|---|---|
| Pipe (NPS/NB) | Nominal bore — NOT actual dimension | Not applicable for 4130 CDS tube |
| Mechanical tube | Actual OD × Wall (in decimal inches or mm) | Correct method for 4130 CDS |
| Example | Specify: OD = 14.000" × Wall = 0.250" CDS | Use this format on purchase orders |
What to Do With a 14" NB Requirement
If a drawing or enquiry asks for 14" NB in 4130, the first step is to find out what the part actually is. A pipeline or pressure piping item should be bought to a pipe standard and a pipe grade, not as mechanical tubing. A machined component such as a large ring or sleeve is a different matter: it needs a finished OD, bore and length, and the material may be supplied as a forged ring, a bored bar or heavy-wall hollow.
4130 mechanical tubing to ASTM A519 is ordered by actual OD and wall and is normally supplied in much smaller diameters. Send the application and the finished dimensions and the enquiry can be answered properly. For the difference between schedules and tube walls see Schedule 40 and 4130 tubing.
Frequently Asked Questions
Is large-diameter 4130 tubing (e.g., 14" OD) available?
The verified OD range for standard supply is 0.25" to 5.0". OD dimensions larger than 5.0" require a special enquiry and are not standard catalogue items. For requirements above 5" OD, contact the supplier with the required OD, wall, and application for a feasibility assessment.
What is the outside diameter of 14" NB pipe?
14.000", which is 355.6 mm. From 14 inch upwards the nominal pipe size equals the actual OD. Below 14 inch the OD is larger than the nominal size.
Does NB mean the same as NPS and DN?
They name the same pipe series in different systems. 14" NB, NPS 14 and DN 350 all refer to pipe with a 355.6 mm outside diameter.
Enquire for Large-OD 4130 Tubing
Specify your required actual OD (in inches or mm) and wall — not NB — for an accurate quotation.
- Actual OD (in inches or mm)
- Wall Thickness
- Length
- Standard
- Application
- Delivery