Table of content
Introduction
Pipe fittings are an important part of the pipeline system, so how are the sizes of pipe fittings determined? Of course, there are different production standards. The size definitions are different according to different standards, such as NPS, OD, ID and SCH.
This article will introduce the sizes of pipe fittings in detail, such as common standards such as ASME B16.9. Pipe fittings also include: elbows, tees, reducers, caps, etc.
What Are Pipe Fittings?
Pipe fittings are a unified name for pipe fittings used to connect and change direction. Common types include:
Elbows (for changing direction)
Tees (for branches)
Reducers (for connecting two pipes of different diameters)
Each type of fitting has a certain production standard, and these standards have uniformly specified sizes.
How Are Pipe Fittings Measured?
The following data are used to measure pipe fittings:
Nominal Pipe Size (NPS)
Outside Diameter (OD)
Wall Thickness
Center to End (C to E)
End to End (E to E)
Standard Fitting Dimensions: ASME B16.9
ASME B16.9 is a common standard for butt-welded pipe fittings, applicable to carbon steel and stainless steel. Some of the pipe fittings specified in this standard are:
Elbows, Tees, Reducers, Caps, Elbows and Crosses.
Sample Dimensions: 90° Long Radius Elbow (ASME B16.9)
| NPS (inches) | Outside Diameter (OD, mm) | Center-to-End (C to E, mm) |
| 1/2″ | 21.3 | 38 |
| 1″ | 33.4 | 51 |
| 2″ | 60.3 | 76 |
| 4″ | 114.3 | 152 |
| 6″ | 168.3 | 229 |
The long diameter of long radius elbows is mostly 1.5D.
Sample Dimensions: Concentric Reducers
| NPS (Large × Small) | OD (Large) | OD (Small) | End-to-End (E to E) |
| 3″ × 2″ | 88.9 mm | 60.3 mm | 102 mm |
| 6″ × 4″ | 168.3 mm | 114.3 mm | 152 mm |
| 8″ × 6″ | 219.1 mm | 168.3 mm | 178 mm |
The center lines of concentric reducers are in a straight line.
Sample Dimensions: Tees (Straight)
| NPS | Outside Diameter | Center-to-End (Run) | Center-to-End (Branch) |
| 2″ | 60.3 mm | 76 mm | 76 mm |
| 4″ | 114.3 mm | 114 mm | 114 mm |
| 6″ | 168.3 mm | 152 mm | 152 mm |
Pipe Schedule vs Fitting Size
| NPS | Schedule 40 OD | Wall Thickness (mm) | Schedule 80 Wall Thickness |
| 1″ | 33.4 mm | 3.38 mm | 4.55 mm |
| 2″ | 60.3 mm | 3.91 mm | 5.54 mm |
| 4″ | 114.3 mm | 6.02 mm | 8.56 mm |
Fitting Dimension Terms You Should Know
| Term | Meaning |
| NPS | Nominal Pipe Size (label, not exact size) |
| OD | Outside diameter of pipe |
| ID | Inside diameter (varies by schedule) |
| C to E | Center to end (for elbows/tees) |
| E to E | End to end (for reducers/couplings) |
| Saddle | Fitting type for branch off a main pipe |
uick Reference: Pipe Fitting Types and Dimensions
| Fitting Type | Size Range (inches) | Common Angles | Standards |
| Elbow (90°, 45°) | 1/2″ – 48″ | 45°, 90° | ASME B16.9 |
| Tee | 1/2″ – 48″ | 90° | ASME B16.9 |
| Reducer | 1/2″ – 48″ | – | ASME B16.9 |
| Cap | 1/2″ – 48″ | – | ASME B16.9 |
| Flanges | 1/2″ – 60″ | – | ASME B16.5/B16.47 |
Pipe Fitting Materials
The materials that can be used to make pipe fittings are:
- Carbon steel: strong and economical, one of the commonly used materials.
- Stainless steel: corrosion-resistant, food grade.
- PVC/CPVC: one of the plastic materials.
- Copper: mostly used for household plumbing pipes.
- HDPE/PE: a kind of plastic, softer.
The production process and use of different materials are also different, so choose according to specific needs.
FAQs for Beginners
Are fittings measured by ID or OD?
The specific measurement of pipe fittings is generally measured according to the inner diameter. The outer diameter has a specified wall thickness according to different production specifications.
Can I mix SCH 40 and SCH 80 fittings?
The two only have different pressure ratings and can be mixed when pressure is not required.
Do all elbows have the same radius?
No, elbows have long radius and short radius.
Summary
To understand pipe fittings, you need to understand the production standards of pipe fittings, and the sizes and specifications corresponding to different production standards. Therefore, the above article hopes to help you understand the specifications and sizes of different pipe fittings: elbows, tees, reducers, pipe caps, etc.
