Table of Contents
MPT VS FPT: What they are?
MPT (Male Pipe Thread) and FPT (Female Pipe Thread) are terms used to describe the gender of pipe threads in plumbing and industrial applications. Here’s the difference:
- MPT (Male Pipe Thread) – Refers to external (outside) threads on a pipe or fitting. It screws into a corresponding female-threaded (internal) component.
- FPT (Female Pipe Thread) – Refers to internal (inside) threads on a pipe or fitting. It accepts a male-threaded (external) component.
Both MPT and FPT typically follow the National Pipe Thread (NPT) standard in the U.S., which is a tapered thread design to create a tight seal. However, some threads are parallel (NPS – National Pipe Straight), which require additional sealing methods like Teflon tape or pipe dope.
Comparison Mpt VS Fpt
| Feature | MPT (Male Pipe Thread) | FPT (Female Pipe Thread) |
|---|
| Thread Type | External (outside) threads | Internal (inside) threads |
| Connection | Screws into a female fitting | Receives a male fitting |
| Standard | Typically follows NPT (tapered) or NPS (straight) | Typically follows NPT (tapered) or NPS (straight) |
| Sealing | Requires Teflon tape, pipe dope, or sealing compound for a leak-proof connection | Also requires Teflon tape, pipe dope, or a gasket depending on application |
| Usage | Used on pipe ends, fittings, and adapters to connect to FPT | Used on couplings, valves, and fittings to receive MPT |
| Common Applications | Plumbing, gas lines, compressed air systems | Plumbing, water supply lines, industrial piping |
How to Install MPT (Male Pipe Thread) and FPT (Female Pipe Thread)
Connections
Proper installation ensures a leak-free and secure connection. Follow these steps:
Tools & Materials Needed:
- MPT (Male Pipe Thread) fitting
- FPT (Female Pipe Thread) fitting
- Teflon tape (PTFE tape) or pipe thread sealant (pipe dope)
- Adjustable wrench or pipe wrench
- Clean rag
Step-by-Step Installation Guide:
Clean the Threads
- Wipe both MPT and FPT threads with a clean rag to remove dirt, debris, or old sealant.
- Inspect for damage (cracks, worn threads) before proceeding.
Apply Thread Sealant (Teflon Tape or Pipe Dope)
- If using Teflon tape:
- Wrap it clockwise around the MPT threads 3–5 times.
- Press it down so it conforms to the threads.
- If using pipe thread sealant (pipe dope):
- Apply a thin, even coat on the MPT threads.
- Avoid excessive application, which can lead to clogging.
Hand-Tighten the MPT into the FPT Fitting
- Insert the MPT fitting into the FPT fitting and turn it clockwise.
- Hand-tighten until it becomes snug.
Use a Wrench to Tighten Further
- Use an adjustable wrench to tighten the connection 1–2 more turns beyond hand-tight.
- Do not over-tighten, as this can crack the fitting or strip the threads.
Test for Leaks
- If using for water or gas, turn on the supply slowly and check for leaks.
- For gas lines, use a soapy water solution – bubbles indicate a leak.
- If a leak is found, disassemble, reapply sealant, and reinstall.
Common Mistakes to Avoid
- Over-tightening – Can damage threads and cause leaks.
- Under-tightening – May not seal properly, leading to leaks.
- Applying Teflon tape backward – Always wrap clockwise so it tightens with the fitting.
- Not using sealant – Required for NPT (tapered) threads to ensure a tight seal.
When to Use Thread Sealant vs. Teflon Tape
| Sealant Type | Best For | Advantages |
|---|
| Teflon Tape | Water, air, small gas fittings | Easy to apply, no mess |
| Pipe Dope | Gas, high-pressure applications | Stronger seal, withstands high temperatures |
FAQs
Are MPT and FPT threads compatible?
Yes, an MPT fitting is designed to screw into an FPT fitting of the same size and thread type.
Do I need sealant for MPT and FPT connections?
Yes, typically Teflon tape or pipe thread sealant (pipe dope) is used for NPT (tapered) threads to prevent leaks.
Can MPT and FPT threads be used for gas or water lines?
Yes, both are commonly used in plumbing, gas lines, air compressors, and hydraulic systems, provided the correct thread type and sealing method are used.
Are MPT and FPT threads always tapered?
Most commonly, they follow NPT (National Pipe Tapered) threads, but some applications use NPS (National Pipe Straight) threads, which require gaskets or O-rings for sealing.
Can I connect an MPT fitting to an FPT fitting of a different size?
No, the fittings must have the same nominal size and thread type to fit properly. If different sizes are needed, a thread adapter or reducer is required.
What’s the difference between MPT/FPT and BSP threads?
MPT/FPT (NPT standard) – Primarily used in North America, with tapered threads for sealing.
BSP (British Standard Pipe) – Used in Europe and other regions, with parallel or tapered threads that may require washers or gaskets.
How can I measure my MPT or FPT threads?
Use a thread gauge or check manufacturer specifications. Pipe sizes do not correspond to actual measurements; for example, a ½” NPT pipe does not measure exactly ½” in diameter.
Can I convert MPT to FPT or vice versa?
Yes, you can use threaded adapters or couplings to transition between MPT and FPT fittings if needed.
READ ALSO: 1/2 vs 5/8 garden hose