What Is a Hex Nipple？
A mamilo hexagonal is a short pipe fitting with male threads on both ends and a hexagonal section in the middle. The hexagon lets you use a wrench instead of a pipe wrench. No damaged threads.
Hex nipples are used in piping systems to:
- Connect two female-threaded fittings
- Extend pipe runs
- Connect pipe to valves, regulators, and instruments
Most hex nipples are male TNP (National Pipe Thread) on both ends. They are available in stainless steel, latão, and carbon steel.
Three Things That Determine Hex Nipple Size
- Thread type and size (NPT or BSP or metric, what diameter)
This is the most basic thing. 1/4“ NPT and 1/2” NPT are very different. Buy the wrong one and it will not thread in.
Common threads: NPT (North America), BSP (Europe, Asia), metric (Germany, China, Japan)
Common sizes: NPT/BSP: 1/8“, 1/4”, 3/8“, 1/2”, 3/4“, 1”, Metric: M10, M12, M14, M16, M18, M20, M22, M24
- Length (end to end)
Length determines how far apart the two connections are. Too short, you cannot reach. Too long, it will not fit.
- Standard length: about 1.5“ to 2.5” (depends on size)
- Long nipple: 6“ to 12” or longer
- Close nipple: threads almost end to end, fittings sit very close together
- Hex size
Hex size tells you what wrench you need. Buy a hex nipple with a hex that is too big, and your wrench will not fit.
Why Size Matters, What Happens If You Pick Wrong？
| Wrong choice | What happens |
| Wrong thread | Will not thread in, or will leak if forced |
| Wrong length | Too short to connect, or too long to fit |
| Wrong material | Corrosion, pressure failure, temperature failure |
The most common mistake: buying a 1/2“ NPT hex nipple for a 1/2” BSP port. They look similar. Thread angle is different (60° vs 55°). It will leak.
Quick Size Reference
Hex Nipple Pressure Ratings
Hex nipple pressure rating depends on material and thread size.
Key points about pressure ratings:
- Smaller size = higher pressure: 1/8“ hex nipples handle up to 10,000 psi; 1” drops to about 4,600 psi
- 316 stainless steel is stronger: Typically 2x the pressure rating of brass
- Always check your material: Brass is for lower pressure applications (water, air, low-pressure gas)
- High-pressure versions exist
Important note: These pressure ratings are for standard hex nipples at room temperature. High-temperature applications reduce pressure capacity. For steam or hot oil service, use stainless steel with temperature-appropriate packing.
When Do You Need a Hex Nipple？
You need to connect two female-threaded ports with a short pipe. For example:
- Between two valves
- Between a valve and a pipe
- Between an instrument and a pipe
Use a hex nipple because the hex center gives you a wrench grip. Use a plain nipple (no hex) and you need a pipe wrench. The pipe wrench will damage the threads.
How to Choose
- Pick the thread type and size (NPT or BSP or metric, what diameter)
- Pick the length (measure the gap between the two ports)
Important note: How to measure the length of a hex nipple？
Measure from end to end. This includes both threaded sections and the hex center. Do not measure only the threaded part.
- Pick the material (stainless steel, brass, carbon steel)
Quick rule:
Corrosive media or high pressure → 316 stainless steel
Clean water, air, low pressure → brass
Oil, gas, dry service → carbon steel
Not sure → pick 316 stainless steel. It works for most applications.
- Check the pressure rating (see table above)
Not sure？ Send us a photo of your port. We will confirm the size before you order.
Perguntas frequentes
Q1. What is the actual outside diameter of 1/4“ NPT thread？
1/4” NPT thread has an outside diameter of about 0.540 inches. This is not the same as 1/4“ tubing (0.250 inches). Do not confuse pipe thread with tube size.
Q2. Can I use a hex nipple to connect two different thread types？
Yes, but you need a reducing hex nipple or a thread conversion hex nipple. For example, 1/2” NPT on one end and 1/2“ BSP on the other. Tell us what you need.
Q3. Do you provide material certificates for hex nipples？
Yes. Material test certificate with heat number, chemical composition, and mechanical properties. In the box. No extra charge.
Q4. Can you make custom length hex nipples？
Yes. Tell us your exact length. We will make it. MOQ is 10 pcs.
We Make Hex Nipples
NPTLOK is a manufacturer with over 20 years experience in producing hex nipples. We have state-of-art equipment, competitive price and quick delivery time, with a wide range of materials, threads, sizes, lengths to choose from:
Materials: 316 stainless steel, brass, carbon steel
Threads: NPT, BSP, metric
Sizes: 1/8“ to 3”
Lengths: standard, long, close
Custom lengths accepted
Need a hex nipple？Contato and tell us the thread, length, and material. We will make it.
