NPT vs JIC Fittings: What's the Difference and Which One Do You Need?
What Are NPT Fittings?
NPT stands for National Pipe Tapered. These fittings use a tapered thread design meaning the threads are slightly angled so they tighten and wedge together as they are turned in. This wedging action is what creates a seal, and because the metal threads alone cannot fully seal against fluid leakage at high pressures, NPT fittings are almost always used with a thread sealant such as PTFE tape or pipe dope.
NPT is governed by ANSI/ASME B1.20.1 and is the dominant standard for pipe-threaded connections in the United States. It is used across plumbing, oil and gas, manufacturing, and hydraulic systems.
Key Characteristics of NPT Fittings
• Tapered thread profile — threads taper at 1° 47' per side
• Sealing achieved through thread deformation plus sealant (PTFE tape or pipe dope)
• Available in a wide range of sizes (1/8" NPT through 4" NPT and beyond)
• Compatible with both low- and high-pressure hydraulic systems when properly sealed
• Commonly used with steel and stainless steel pipe connections
• Standard in U.S. industrial, construction, agricultural, and automotive applications
At Gear House Hydraulics, our NPT Fittings line (available in both steel and stainless steel) includes a comprehensive selection for industrial, mobile, and instrumentation hydraulic systems. Our stainless NPT fittings are ideal for corrosive environments, marine applications, and sanitary systems where rust resistance is critical.
What Are JIC Fittings?
JIC stands for Joint Industry Council. These fittings are defined by their 37-degree flare seat a cone-shaped seating surface machined at 37 degrees that mates with a corresponding flared tube or hose end. When two JIC fittings are tightened together, the metal-to-metal contact between the flare seats creates a reliable, leak-resistant seal without any additional sealant required.
Key Characteristics of JIC Fittings
• 37-degree flare seat creates a metal-to-metal seal
• No thread sealant required the cone-to-cone contact does the work
• Rated for high-pressure hydraulic service (up to 10,000 PSI depending on size and configuration)
• Reusable can be disconnected and reconnected without losing sealing ability
• Straight (non-tapered) threads hold the fitting in place while the flare seals
• Available in a broad size range, commonly designated by dash size (e.g., -4, -6, -8, -10, -12)
• Widely used in hydraulic hose assemblies, tube fittings, and instrumentation
Gear House Hydraulics stocks 37 Degree JIC/AN Fittings in both steel and stainless steel. Our JIC product line includes tube nuts (such as the 0318 JIC Tube Nut), JIC caps (0304-C JIC Cap) for thread protection when ports are not in use, and JIC plugs (2408 JIC Plug) for capping off open lines during maintenance or storage. These components are essential for any complete hydraulic build.
NPT vs JIC: A Side-by-Side Comparison
Understanding the difference between these two fitting types will help you make better decisions for your hydraulic or fluid power system.
Sealing Method
NPT seals through tapered thread deformation, requiring PTFE tape or pipe dope. JIC seals through metal-to-metal contact at the 37-degree flare seat no sealant needed.
Thread Type
NPT uses tapered threads that tighten by wedging. JIC uses straight threads that clamp the flare seat together.
Pressure Rating
Both can handle hydraulic pressures when properly specified, but JIC fittings are generally preferred for high-pressure hydraulic lines due to their reliable metal-to-metal seal. NPT connections sealed with sealant can be more susceptible to vibration-induced loosening over time.
Reusability
JIC fittings are highly reusable simply disconnect and reconnect without degrading the seal. NPT connections may require reapplication of sealant each time they are reassembled.
Installation
NPT connections require careful torquing and application of sealant to every male thread. JIC connections are cleaner and faster align the flare, hand-tighten, and torque to spec.
Common Applications
NPT: plumbing, gas lines, lower-pressure hydraulic ports, manifolds, and instrumentation. JIC: high-pressure hydraulic hose ends, tube fittings, mobile equipment, agricultural machinery, and fluid power systems.
Material Options
Both NPT and JIC fittings are available in carbon steel and stainless steel at Gear House Hydraulics, making them suitable for standard industrial environments as well as corrosive or high-purity applications.
When Should You Use NPT Fittings?
NPT fittings are the right choice when:
• You are connecting to a port or manifold that is already threaded in NPT
• The application involves low-to-medium pressure and a sealant is acceptable
• You are working on pipe-based systems rather than hose or tubing assemblies
• The system requires compliance with U.S. pipe thread standards (ANSI/ASME B1.20.1)
• You need stainless steel fittings for corrosive or sanitary environments — Gear House Hydraulics offers Stainless NPT Fittings for exactly these applications
When Should You Use JIC Fittings?
JIC fittings are the right choice when:
• You are building or repairing high-pressure hydraulic hose assemblies
• The system experiences significant vibration (construction, agriculture, mobile equipment)
• You need a clean, reliable, sealant-free connection that can be disconnected and reconnected
• The application calls for SAE J514 compliance
• You want a metal-to-metal seal that will not degrade in high-temperature or high-pressure conditions
• You need stainless JIC fittings for marine, chemical, or food-grade hydraulic systems available as Stainless 37 Degree JIC/AN Fittings at Gear House Hydraulics
Gear House Hydraulics Product Lineup: NPT and JIC Fittings
At Gear House Hydraulics, we carry a full range of NPT and JIC fittings in both steel and stainless steel. Below is a summary of what you will find in our catalog:
Steel Hydraulic Fittings
• NPT Fittings — Standard carbon steel NPT fittings for industrial and hydraulic pipe connections
• 37 Degree JIC/AN Fittings — Full range of JIC/AN fittings including tube nuts (0318 JIC Tube Nut), caps (0304-C JIC Cap), and plugs (2408 JIC Plug)
• ORB Fittings — O-Ring Boss fittings for leak-free port connections
• ORFS Fittings — O-Ring Face Seal fittings for high-vibration, high-pressure systems
• Flange Components — Including split flange kits such as the 1902 Split Flange Kit Code 62 and the 1824 O-Ring Flange Plug/Split Code 62
• BSPP/BSPT Fittings — British Standard fittings for international or OEM equipment
• Hose Steel Hydraulic Fittings — Fittings designed specifically for hose end connections
Stainless Steel Hydraulic Fittings
Every fitting category above is also available in stainless steel for demanding environments:
• Stainless NPT Fittings — Including the 1404SS NPT Male Pipe to NPSM Female Pipe Swivel Straight for flexible, corrosion-resistant connections
• Stainless 37 Degree JIC/AN Fittings
• Stainless ORB Fittings
• Stainless ORFS Fittings
• Stainless Flange Components
• Stainless BSPP/BSPT Fittings
• Hose Stainless Hydraulic Fittings
We also carry specialty adapters and swivels such as the 1503 NPTF Pipe Male to NPSM Pipe Female Swivel 45° Elbow and the 1601 NPSM Pipe Female Swivels to NPTF Pipe Male Branch Tee making it easy to route your hydraulic lines in tight spaces or around obstacles.
Coming Soon: Hoses, Hose Ends, Quick Disconnects & Custom Assemblies
Gear House Hydraulics is expanding its product line. Coming soon to our catalog:
• Custom Hose Assemblies — Built to your exact specifications and order request
• Hose — A wide selection of hydraulic hose for low, medium, and high-pressure applications
• Hose Ends — The complementary ends that connect your hose to JIC, NPT, and other fittings
• Quick Disconnects — For fast, tool-free connection and disconnection of hydraulic lines
Frequently Asked Questions
Can I connect NPT fittings to JIC fittings?
Not directly — they use different thread standards and sealing methods. However, adapters are available that convert between NPT and JIC (or other fitting types). At Gear House Hydraulics, our team can help you identify the right adapter for your system.
Do JIC fittings need Teflon tape?
No. JIC fittings seal through metal-to-metal contact at the 37-degree flare. Adding PTFE tape to JIC threads is actually a common mistake that can prevent the fitting from seating properly.
What does the dash size on a JIC fitting mean?
The dash number refers to the tube outside diameter in sixteenths of an inch. For example, a -8 JIC fitting connects to a tube with a 1/2" (8/16") outside diameter.
Are NPT and NPTF the same thing?
They are similar but not identical. NPTF (National Pipe Tapered Fuel) is designed to create a more reliable metal-to-metal seal without sealant in some applications, while standard NPT relies on sealant. Many of our fittings — such as the 1503 NPTF to NPSM swivel elbow — are designed with NPTF threads for improved performance.
Which fitting type is better for high-pressure systems?
JIC fittings are generally preferred for high-pressure hydraulic lines due to their metal-to-metal seal, vibration resistance, and reusability. For port-to-port connections where NPT is required, ensure proper sealant application and torque.
Knowing which fitting to use and having access to a full range of both is essential for keeping your equipment running. That is exactly what Gear House Hydraulics is here for.
Shop our full selection of NPT Fittings, JIC/AN Fittings, and specialty adapters at gearhousehydraulics.com. Have a question or need a custom assembly? Call us at +1 (209) 629-7113 or reach out at john@gearhousehydraulics.com — our expert team is ready to help, 24/7.
