Here we’ll explain the difference between OD and NB and help you make an informed decision when purchasing steel pipes.
Nominal Diameter (NB)
Nominal Diameter (NB) is a term used to describe the standardized size of a steel pipe. It is the size that the pipe is given when it is manufactured, and it is used as a reference for designating pipe sizes. The Nominal Diameter is typically expressed in inches or millimeters, depending on the unit of measurement used in the region.
Out Diameter (OD)
Out Diameter (OD) is the actual outside diameter of a steel pipe. It is the measurement that you would take if you were measuring the pipe’s circumference with a tape measure. The OD is usually expressed in inches or millimeters, and it can vary slightly from the Nominal Diameter, depending on the manufacturing process used.
The Difference Between OD and NB
The main difference between OD and NB is that NB is a standardized size, while OD is an actual measurement. When a steel pipe is manufactured, it is given a Nominal Diameter based on a standard size chart. However, due to variations in the manufacturing process, the actual outside diameter of the pipe may be slightly different from the Nominal Diameter.
For example, a 2-inch NB steel pipe may have an actual outside diameter of 2.375 inches (60.3 mm). This difference between the Nominal Diameter and the actual outside diameter is known as the pipe’s wall thickness. The wall thickness is essential because it affects the pipe’s strength and durability.
Why OD vs NB Matters
Understanding the difference between OD and NB is crucial when purchasing steel pipes because it ensures that you get the right size for your project. If you order a steel pipe based on its Nominal Diameter and don’t take into account the actual outside diameter, you may end up with a pipe that doesn’t fit your needs.
For example, if you need a steel pipe with an outside diameter of 2 inches, but you order a pipe with a Nominal Diameter of 2 inches, you may end up with a pipe that has an actual outside diameter of 2.375 inches. This could lead to installation problems, as well as structural issues down the line.