Threaded Steel Pipe Nipples: Sizes, Dimensions & Compatibility Chart
Threaded
steel pipe nipples are essential components in plumbing, oil & gas, HVAC, and industrial piping systems. They provide secure, leak-proof connections between pipes, valves, and fittings. Choosing the right size, material, and thread type is critical for system integrity.
This guide covers:
Standard sizes & dimensions (NPT, BSP, metric)
Material compatibility (carbon steel, stainless, galvanized)
Pressure ratings & temperature limits
Thread standards (NPT vs. BSP vs. metric)
Downloadable sizing chart
Standard Threaded Steel Pipe Nipple Sizes
Threaded pipe nipples come in various lengths and diameters, categorized by:
A. Nominal Pipe Size (NPS)
| NPS
(inches) |
Actuall OD
(inches) |
Threads per
INCH(TPI) |
| 1/8 |
0.405 |
27 |
| 1/4 |
0.54 |
18 |
| 3/8 |
0.675 |
18 |
| 1/2 |
0.84 |
14 |
| 3/4 |
1.05 |
14 |
| 1 |
1.315 |
11.5 |
| 1 1/2 |
1.9 |
11.5 |
| 2 |
2.375 |
11.5 |
B. Common Lengths
Close nipple (shortest, fully threaded)
Short nipple (1–2" longer than close)
Long nipple (custom lengths up to 12")
Thread Standards & Compatibility
A. NPT (National Pipe Thread) – USA Standard
Tapered threads (seal via thread deformation)
Common in North America
Requires thread sealant (Teflon tape, pipe dope)
B. BSP (British Standard Pipe) – Global Use
BSPT (tapered) & BSPP (parallel)
Common in Europe, Asia, Australia
Not interchangeable with NPT
C. Metric Threads (ISO 228/7)
Used in machinery & automotive
M-style threads (e.g., M10, M12)
⚠ Warning: Mixing NPT and BSP can cause leaks! Always verify thread type.
Material Selection Guide
Carbon steel
Stainless steel 304 & 304L
Stainless steel 316 & 316L
The stainless steel pipe nipple size chart
Material: ASTM A312, Type 304/304L or 316/316L ；Welded or Seamless
Threads: ANSI/ASME B 1.20.1
| Pipe
Size |
B |
A. Length |
| Pipe
O.D. |
Close |
Space |
| 1/8 |
0.405 |
3/4 |
1 1/2 |
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 1/4 |
0.54 |
7/8 |
1 1/2 |
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 3/8 |
0.675 |
1 |
1 1/2 |
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 1/2 |
0.84 |
1 1/8 |
1 1/2 |
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 3/4 |
1.05 |
1 3/8 |
1 1/2 |
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 1 |
1.315 |
1 1/2 |
|
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 1 1/4 |
1.66 |
1 5/8 |
|
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 1 1/2 |
1.9 |
1 3/4 |
|
2 |
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 2 |
2.375 |
2 |
|
|
2 1/2 |
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 2 1/2 |
2.875 |
2 1/2 |
|
|
|
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 3 |
3.5 |
2 5/8 |
|
|
|
3 |
3 1/2 |
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 4 |
4.5 |
2 7/8 |
|
|
|
|
|
4 |
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 5 |
5.563 |
3 |
|
|
|
|
|
|
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 6 |
6.625 |
3 1/8 |
|
|
|
|
|
|
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 8 |
8.625 |
3 1/2 |
|
|
|
|
|
|
4 1/4 |
5 |
5 1/2 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
Pressure & Temperature Ratings
Schedule 40: Standard for general plumbing (300–1000 PSI)
Schedule 80: High-pressure industrial use (1000–3000 PSI)
Temperature Limits:
Carbon steel: Up to 500°F (260°C)
Stainless steel: Up to 800°F (427°C)
How to Measure a Threaded Nipple
1. Determine Nominal Pipe Size (NPS) – Measure outer diameter (OD).
2. Check Thread Pitch– Use a thread gauge (TPI for NPT, pitch for metric).
3. Verify Length – Measure from end to end (including threads).
📌 Pro Tip: Always use a thread sealant (Teflon tape for NPT, Loctite for BSPP).
Common Applications
✔ Plumbing – Connecting water lines, valves
✔ Oil & Gas – High-pressure pipe joints
✔ HVAC – Refrigerant & steam lines
✔ Industrial Machinery** – Hydraulic fittings
Where to Buy Quality Threaded Nipples
- ASTM A53 (Carbon steel)
- ASTM A312 (Stainless steel)
- API 5L (Oil & gas certified)
Final Thoughts
Thread type (NPT/BSP/Metric)
Material (carbon/stainless/galvanized)
Pressure & temperature requirements
#Piping #Plumbing #OilAndGas #HVAC #Engineering #IndustrialMaintenance
