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National Pipe Taper (NPT) and National Pipe Tapered for Fuels (NPTF) are two types of threaded pipe standards. Both are used for creating tight connections between pipes and fittings, but they have some key differences that make them unique. Here’s a simplified breakdown:
Standards:
- NPT threads should be made according to ANSI B1.20.1.
- NPTF threads should be made according to ANSI B1.20.3.
Dimensions:
- Both NPT and NPTF threads have differences in their major and minor diameters, as well as in the shapes of their thread roots and crests.
- NPTF threads have a more restricted range for the crest dimensions compared to NPT threads.
Sealing Mechanism:
- NPTF threads are designed to create a mechanical seal by deforming the thread form during assembly. This makes them leak-proof without needing an additional seal.
- NPT threads, on the other hand, require an additional sealant to be leak-proof because they are designed to have clearance with the mating threads.
Gauge Requirements:
- For pipes larger than ½ inch, NPT and NPTF have different L1 gauge requirements, making them non-interchangeable.
- The key difference lies in the Plug Gage Major Diameter and Ring Gage Minor Diameter.
Inspection:
- NPT threads require simpler inspection. You only need a single L1 plug for internal threads and a single thin L1 ring for external threads to check the size.
- NPTF threads require more comprehensive inspection. Additional L2 and L3 threads in assembly are checked, and both the major and minor diameters are inspected using special plug or ring gauges.
In summary, while both NPT and NPTF threads serve similar purposes, they differ in dimensions, sealing mechanisms, gauge requirements, and inspection procedures.
Hydraxio is a leading manufacturer of stainless steel hydraulic fittings for over 20 years. NPT and NPTF fittings both are available. Please feel free to contact us for more details.
