NPSM Fittings

Stainless Steel NPSM Hydraulic Fittings – NPT Female Swivel Adapters for Leak-Free Connections

QC Hydraulics is a China-based manufacturer with over 25 years of experience in producing stainless steel NPSM fittings. We offer corrosion-resistant, high-pressure solutions for hydraulic, marine, and industrial systems, with bulk supply and OEM/ODM services for global distributors and OEMs.

Explore Our Full Range of NPSM Fittings & Adapters

Stainless Steel NPSM fittings—commonly referred to as NPT Female Swivel fittings—feature a straight NPSM thread and a 30° cone seat that forms a mechanical seal when mated with an NPTF male pipe fitting.

QC Hydraulics manufactures precision-engineered NPT Female Swivel hydraulic adapters, where the swivel nut is permanently attached to the fitting body. These fittings are designed to mate with NPTF male threads that have a 30° chamfered seat. When assembled, the two 30° surfaces (flare and chamfer) create a secure metal-to-metal seal—ensuring leak-free performance in high-pressure hydraulic systems.

✔ Rated up to 6,000 PSI

✔ Wide size range: 1/8″ to 2″

✔ Leak-free, vibration-resistant design

✔ Made of 316Ti / 316L / 304 stainless steel

✔ Precision-machined to ANSI/ASME B1.20.1

✔ Fitting types: straight, 45° & 90° elbows, tee

✔ Thread types: NPT male/female, NPTF male/female

NPSM Fittings Thread Sizes & Dimensions

Thread Size (NPSM) Thread Pitch (TPI) Major Diameter (inch) Hex Size (inch) Material Options
1/8″-27 27 0.405 0.50 304/316/316Ti SS
1/4″-18 18 0.540 0.56 304/316/316Ti SS
3/8″-18 18 0.675 0.75 304/316/316Ti SS
1/2″-14 14 0.840 0.88 304/316/316Ti SS
3/4″-14 14 1.050 1.06 304/316/316Ti SS
1″-11.5 11.5 1.315 1.31 304/316/316Ti SS
1-1/4″-11.5 11.5 1.660 1.63 304/316/316Ti SS
1-1/2″-11.5 11.5 1.900 1.88 304/316/316Ti SS
2″-11.5 11.5 2.375 2.38 304/316/316Ti SS

NPSM Fittings Pressure Ratings

Working pressure ratings are designed to meet a minimum burst pressure ratio of 4:1.

Nom SAE
Dash Size		 Nom Inch
Pipe O.D.		 Thread Size Fittings With NPTF
Pipe Threads		 Adapter Unions
Dryseal Pipe Thread
(NPTF1)		 Straight Pipe Thread
(NPSM2)		 MPa psi MPa psi
-2 1/8 1/8-27 1/8-27 34.5 5000 34.5 5000
-4 1/4 1/4-18 1/4-18 27.5 4000 34.5 5000
-6 3/8 3/8-18 3/8-18 21 3000 27.6 4000
-8 1/2 1/2-14 1/2-14 21 3000 24.1 3500
-12 3/4 3/4-14 3/4-14 17 2500 15.5 2250
-16 1 1-11-1/2 1-11-1/2 14 2000 13.8 2000
-20 1 1/4 1-1/4-11-1/2 1-1/4-11-1/2 8 1150 11.2 1625
-24 1 1/2 1-1/2-11-1/2 1-1/2-11-1/2 7 1000 8.6 1250
-32 2 2-11-1/2 2-11-1/2 7 1000 7.8 1125

1 Dryseal American Standard Taper Pipe Thread
2 American Standard Straight Pipe Thread for Mechanical Joints

Assembly Instructions For Adapter Unions/
Female NPSM Pipe Swivel Ends

NPSM Fittings

1. Inspect components for damage or contamination.
2. Check for 30 degree female seat on male pipe end.
3. Align tube/hose to mating swivel allowing hand connection. To assure proper alignment, two to three turns of nut should be easily permitted.
4. Tighten swivel nut to recommended torque listed in the following table.

Notes:

Refer to the appropriate assembly instruction for adapter union port ends, i.e.: male pipe, female pipe or O-Ring straight thread.

Female NPSM pipe swivels seal on the male nose of the female swivel end and the 30 degree female seat on the male pipe end. The NPSM swivel nut uses a straight mechanical pipe thread and is not a sealing member.

Ensure that the male pipe end to be assembled has been machined with the optional 30 degree female seat. A standard 45 degree chamfer will not seal properly.

Assembly Torque, SAE J1926-3 Adapter Unions and Pipe Fittings
(T.F.F.T. for Tapered Pipe Only)1
Pipe Size Adapter Unions Pipe
Ft. Lbs. Max. Nm. Max. Tapered Pipe T.F.F.T.2 (Turns)
1/16 —- —- 3/4–1 3/4
1/8 13 18 3/4–1 3/4
1/4 20 27 3/4–1 3/4
3/8 25 34 1/2–1 1/2
1/2 47 64 1/2–1 1/2
3/4 84 114 1/2–1 1/2
1 129 175 1/2–1 1/2
1-1/4 152 206 1/2–1 1/2
1-1/2 152 206 1/2–1 1/2
2 300 407 1/2–1 1/2

1 Lubricated assembly.
2 Tapered pipe connections use turns from finger tight. Turn past minimum for alignment of shape fittings.

Technical Support

QC Hydraulics has the capability to engineer, design and manufacture from a concept to the real products.

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Please feel free to contact us if you have any inquiries

QC Hydraulics, Your Premier Stainless Steel Hydraulic Fittings And Adapters manufacturer

QC Hydraulics is a leading manufacturer of stainless steel hydraulic hose fittings, hydraulic adapters, tube fittings and PTFE hose assembly for over 20 years. Our outstanding team, state of the art technology, strict quality control, strong production capacity as well as professional service, enable us enjoying a great reputation in domestic and overseas.

Our products are widely recognized by those global hydraulic & industrial wholesalers/distributors and OEMs in the fields of hydraulic, pneumatic, oil & gas, chemical, marine and shipbuilding etc. Besides, we are also doing OEM service for several of worldwide big brand manufacturers of hydraulic fittings, which greatly reduce their production costs, and help them win more market share.

Now QC Hydraulics become more and more popular in high quality market overseas. We always meet even exceed customer’s expectations. QC Hydraulics is a reliable and trusted supplier of wholesalers, distributors and brand manufacturers of hose and fittings.

  • State of The Art Facilities

  • Over 20 years’ Manufacturing Experience

  • Highly strict Quality Control & Inspection

  • Annual production capacity Over 4.5 million of fittings

Why Choose Us

State of The Art Facilities

We utilize state-of-the-art facilities and equipment to produce industry leading, quality stainless steel hydraulic fittings. Each facility supervisor has over 10 years of experience in the industry. Manufacturing, sales & technical support, warehouse, shipping, and quality control-have specific objectives that contribute to our overall goal of 100% customer’s satisfaction.

Zero Quality Issues

When you buy QC Hydraulics’ products, you are buying precision and reliability.In the hydraulic industry, where extreme pressures prevail, precision and accuracy are paramount. Our Quality Control Department follows strict Quality Assurance Program procedures that make certain our products meet your quality requirements. Besides, 3.1 material certificate available for each shipment to ensure you receive 100% right materials from us.

100% On-Time Delivery

With QC Hydraulics, you’ll have one less thing to worry about. We have maintained a 99.99% on-time delivery rate for 3 years in a row. That kind of consistency doesn’t just happen, we make it happen. Besides, we have the commonly used raw materials and accessories in stock that enable us make a very quick delivery time for the urgent orders.

Professional Service

As a professional manufacturer, our engineering department can provide technical service. Like new products designing, CAD drawings and technical advice. Our overseas sales department are 100% well trained with strong industry & product knowledge and service awareness, who can make a quick response within 24 hours to greatly improve the communication efficiency.

Frequently Asked Questions

We manufacture a wide range of stainless steel hydraulic adapters, including:

JIC, ORFS, NPT, NPTF, BSP, BSPT, SAE, and Metric thread types

Straight, 45° & 90° elbows, tees, crosses, reducers, and plugs

Interchangeable with Parker and Eaton standard adapters

Our adapters are designed to meet SAE, ISO, DIN, and JIS standards.

Yes, we provide standard bulk packaging as well as custom packaging options based on customer requirements. Our standard packaging includes:

Plastic caps and plugs to protect threads and sealing surfaces

Individual polybags for small-sized adapters

Heavy-duty cartons with reinforced packing for safe transportation

For distributors and wholesalers, we can also provide private labeling and custom branding.

We manufacture adapters using high-quality stainless steel:

AISI 304 (1.4301)

AISI 316L (1.4404)

AISI 316Ti (1.4571)

These materials provide superior corrosion resistance, making them ideal for high-pressure and harsh environments

Yes, we do both hydrostatic pressure and nitrogen gas pressure test. Testing reports are avaliable.

Yes, we offer custom manufacturing services for hydraulic adapters based on customer drawings, specifications, or samples. Our engineering team can assist with design modifications, thread compatibility, and performance optimization to meet specific application requirements.

Our standard MOQ is 200 pieces per item, but for larger sizes (above 1 inch), we can accept 100 or even 50 pieces. We are flexible with initial orders to help customers test our quality

Yes, we provide EN 10204 3.1 material certificates for all shipments. Our stainless steel raw materials meet ASTM A276 and ASTM A182 standards, ensuring compliance with industry regulations.

Stainless Steel Only: Unlike many suppliers who offer both carbon steel and stainless steel, we focus exclusively on stainless steel, ensuring better precision and quality.

Advanced Manufacturing: We use high-precision CNC machining and strict quality control measures.

Guaranteed Quality: 100% pressure-tested, dimensionally accurate, and ISO 9001 certified.

On-Time Delivery: Reliable lead times and stock management ensure prompt shipments.

Interchangeability: Compatible with leading global brands like Parker and Eaton.

Send us a message if you have any questions or request a quote.

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