## What is nominal pipe size?

Nominal pipe size refers to only the outside diameter (OD) of a pipe making it somewhat vague. For example, when we say pipe size is 2 NPS, it refers to all the pipes having 2.375-inch (or 60.3 mm) as outside diameter irrespective of wall thickness and thus the inside diameter.

**What are the dimensions of a pipe?**

Steel Pipe Sizes – Schedule 40

NPS | Outside Diameter (in) | Weight (lb/ft) |
---|---|---|

3/8 | 0.675″ | 0.57 lb/ft |

1/2 | 0.840″ | 0.85 lb/ft |

3/4 | 1.050″ | 1.13 lb/ft |

1 | 1.315″ | 1.68 lb/ft |

**Is DN and NB the same?**

In the inch system, nominal bore is abbreviated as NB; in metric systems, it is “diameter nominal” (DN), or Nominal Pipe Size (NPS) in North America. Above that size, the NB is the SAME as the outside diameter!

### Is pipe size measured by ID or OD?

OD and Nominal Pipe Size Tubing is measured by the OUTSIDE DIAMETER (O.D.), specified in inches (e.g., 1.250) or fraction of an inch (eg. 1-1/4″). Pipe is usually measured by NOMINAL PIPE SIZE (NPS). Although it is related to the outside diameter, it is significantly different.

**Why do we use nominal diameter?**

The value of the nominal diameter is close to the inner diameter of the pipe but not equal to it, and is adopted in order to unify the connecting dimensions of the pipe and pipe fittings.

**What do you mean by nominal diameter?**

The term “Nominal Diameter” when used to describe the size (diameter) of pipe used in construction of standard railings and posts means the outside diameter.

## How do you measure plumbing pipe diameter?

To find it, measure around the circumference of the pipe with flexible measuring tape. Divide the circumference by pi, or about 3.14159. For example, if the circumference is 12.57 inches (319 mm), you would divide by pi, and get an outside diameter of about 4 inches (100 mm).

**What is the difference between nominal and inside diameter?**

Nominal Pipe Size (NPS) is a North American set of standard sizes for pipe. The term nominal refers to pipe in non-specific terms and identifies the inside diameter with a non-dimensional number. The difference between the inside diameter (ID) and the outside diameter (OD) is due to the thickness of the wall.

**What is nominal diameter?**

Nominal Diameter is also known as the mean or average outside diameter and is represented by DN. It is neither equal to the inner diameter (ID) nor the outer diameter (OD) of the pipe. Pipes having identical nominal diameters can be easily connected or interchanged with each other.