NPSM Fittings – Reliable Straight Thread Hydraulic Connections
NPSM (National Pipe Straight Mechanical) fittings are widely used in hydraulic, pneumatic, and fluid systems to create (parallel) and rely on gaskets to achieve a tight seal.
At Strongflex, we pride ourselves on high-quality NPSM fittings with precision-machined threads, robust materials, and corrosion-resistant surface treatments—guaranteeing reliable performance and extended service life in demanding hydraulic systems.
NPSM Female 60° cone / SAE J514 - 21611
Material: Carbon steel #45 Stainless steel
Application: Used for 1SN/2SN hose.
T type fitting: 21611T
Double nut fitting: 21611D
Spiral hose fitting: 21612
| Part No. | Thread | DN | DASH | A | C | S2 |
| 21611-04-04 | 1/4″ × 18 | 6 | 4 | 18 | 4.6 | 19 |
| 21611-04-06 | 1/4″ × 18 | 10 | 6 | 19 | 4.6 | 19 |
| 21611-06-04 | 3/8″ × 18 | 6 | 4 | 19 | 6 | 22 |
| 21611-06-05 | 3/8″ × 18 | 8 | 5 | 19 | 6 | 22 |
| 21611-06-06 | 3/8″ × 18 | 10 | 6 | 19 | 6 | 22 |
| 21611-08-08 | 1/2″ × 14 | 12 | 8 | 21.5 | 7.5 | 27 |
| 21611-12-10 | 3/4″ × 14 | 16 | 10 | 24 | 8.9 | 32 |
| 21611-12-12 | 3/4″ × 14 | 20 | 12 | 24 | 8.9 | 32 |
| 21611-16-12T | 1″ × 11.5 | 20 | 12 | 25 | 10.5 | 41 |
| 21611-16-16 | 1″ × 11.5 | 25 | 16 | 27 | 10.5 | 41 |
| 21611-20-20W | 1.1/4″ × 11.5 | 32 | 20 | 29.5 | 11.2 | 50 |
| 21611-24-24W | 1.1/2″ × 11.5 | 40 | 24 | 29.5 | 11.2 | 55 |
45° NPSM Female 60° cone / SAE J514 - 21641
Material: Carbon steel #45 Stainless steel
Application: Used for 1SN/2SN hose.
T type fitting: 21641T
Double nut fitting: 21641D
Spiral hose fitting: 21642
| Part No. | Thread | DN | DASH | A | C | H | S2 |
| 21641-04-04 | 1/4″ × 18 | 6 | 4 | 45.1 | 4.6 | 23 | 19 |
| 21641-06-06 | 3/8″ × 20 | 10 | 6 | 47.2 | 6 | 24.9 | 22 |
| 21641-08-08 | 1/2″ × 14 | 12 | 8 | 62.7 | 7.5 | 27.7 | 27 |
| 21641-12-12 | 3/4″ × 14 | 20 | 12 | 81.4 | 8.9 | 34 | 32 |
| 21641-16-16 | 1″ × 11.5 | 25 | 16 | 89.2 | 10.5 | 35 | 41 |
| 21641-20-20W | 1.1/4″ × 11.5 | 32 | 20 | 99.8 | 11.2 | 39.3 | 50 |
| 21641-24-24W | 1.1/2″ × 11.5 | 40 | 24 | 115.1 | 11.2 | 44.4 | 55 |
| 21641-32-32W | 2″ × 11.5 | 50 | 32 | 136.4 | 11.2 | 63.4 | 70 |
90° NPSM Female 60° cone / SAE J514 - 21691
Material: Carbon steel #45 Stainless steel
Application: Used for 1SN/2SN hose
T type fitting: 21691T
Double nut fitting: 21691D
Spiral hose fitting: 21692
| Part No. | Thread | DN | DASH | A | C | H | S2 |
| 21691-04-04 | 1/4″ × 18 | 6 | 4 | 30 | 4.6 | 40.5 | 19 |
| 21691-06-04 | 3/8″ × 18 | 6 | 4 | 30 | 6 | 37.7 | 22 |
| 21691-06-05 | 3/8″ × 18 | 8 | 5 | 34 | 6 | 40.7 | 22 |
| 21691-06-06 | 3/8″ × 18 | 10 | 6 | 35.3 | 6 | 45.3 | 22 |
| 21691-08-08 | 1/2″ × 14 | 12 | 8 | 41 | 7.5 | 53.2 | 27 |
| 21691-12-10 | 3/4″ × 14 | 16 | 10 | 56.5 | 8.9 | 53.5 | 32 |
| 21691-12-12 | 3/4″ × 14 | 20 | 12 | 65.5 | 8.9 | 69.1 | 32 |
| 21691-16-12T | 1″ × 11.5 | 20 | 12 | 65.5 | 10.5 | 64.5 | 41 |
| 21691-16-16 | 1″ × 11.5 | 25 | 16 | 76.7 | 10.5 | 75 | 41 |
| 21691-20-20W | 1.1/4″ × 11.5 | 32 | 20 | 91.5 | 11.2 | 86 | 50 |
| 21691-24-20T | 1.1/2″ × 11.5 | 32 | 20 | 91.5 | 11.2 | 83.5 | 55 |
| 21691-24-24W | 1.1/2″ × 11.5 | 40 | 24 | 109.4 | 11.2 | 102 | 55 |
| 21691-32-32W | 2″ × 11.5 | 50 | 32 | 131.8 | 11.2 | 125 | 70 |
NPSM Fitting Feature
The NPSM fittings sealing method provides several benefits:
- No need for thread sealants or PTFE tape.
- Easy assembly and disassembly.
- Reusable without damaging threads.
- Consistent alignment and connection integrity.
Because of these advantages, NPSM fittings are commonly used in systems requiring frequent maintenance or assembly without compromising sealing reliability.
NPSM Technical Characteristics
Thread Type: Straight (Parallel) thread
Thread Angle: 60°
Standard: ANSI/ASME B1.20.1
Material Options: Carbon Steel, Stainless Steel, Brass, Aluminum
Surface Treatment: Zinc Plated, Nickel Plated, Black Oxide, Customized Coating
Size Range: 1/8” to 2”
Working Pressure: Up to 6,000 psi (depending on size and material)
Temperature Range: -40°C to +120°C
Strongflex offers custom NPSM fittings to meet your system’s pressure, temperature, and media requirements. We also support OEM and ODM production.
NPSM Fittings Application
NPSM fittings are suitable for a variety of industrial and hydraulic systems requiring reliable straight thread connections. Common applications include:
Valve-to-pipe transitions: Utilizing fluororubber gaskets ensures long-term, leak-free operation.
Quick Equipment Assembly and Disassembly: NPSM’s straight threads facilitate installation and disassembly.
Low-Pressure Sealing Systems: Compared to NPT fittings, which are designed for high-pressure systems, NPSM fittings are more suitable for low-pressure systems. For example, in the water treatment industry, EPDM gaskets are used to maintain a seal at pressures up to 2 MPa.
NPSM Fitting Types We Supply
Strongflex manufactures and supplies a comprehensive range of NPSM fittings and adapters, including:
NPSM Female Swivel Fittings – For flexible hose assemblies, providing easy installation and maintenance.
NPSM Male Adapters – Used to connect pipes or hoses to other thread standards.
NPSM Female Adapters – Suitable for joining male-threaded components.
NPSM to JIC Adapters – For connecting straight-thread fittings with 37° flare JIC threads.
NPSM to ORFS Adapters – Ensure a secure, O-ring face seal connection.
Custom Machined NPSM Fittings – Tailored to customer drawings or special material requirements.
Every fitting is produced under strict dimensional control and pressure-tested to ensure reliable sealing performance in demanding hydraulic applications.
FAQ
Is NPSM the same as NPT?
NPSM, short for American Standard Mechanical Pipe Joint Thread, is a cylindrical pipe thread used for mechanical connections under US standards. NPT, also known as National Pipe Thread, is a 60-degree tapered pipe thread widely used in North America. The main difference between NPT and NPSM is that NPT threads are tapered, while NPSM threads are cylindrical.
Are NPSM threads compatible with NPT threads?
While NPT and NPSM threads differ significantly in structure, they can be used together in some situations. This primarily depends on whether their nominal diameters and thread counts match. However, it’s important to note that because NPT threads have a taper and NPSM threads do not, there may be some play when mating, which can affect the seal and stability of the connection.
