304 Stainless Steel Compression Fitting Female Straight Coupling — Leak-Free, Multi-Size
Chasing a slow leak at a tubing junction is one of the most frustrating problems in any fluid or pneumatic system. Plumbers, HVAC technicians, instrumentation engineers, and serious DIYers who work with stainless tubing need a 304 stainless steel compression fitting that creates a reliable, vibration-resistant seal the first time — without special tools or thread sealant on the compression end.
Each piece is a female straight coupling compression connector machined from 304 stainless steel. The female threaded end accepts standard NPT fractional sizes — 1/8" (≈3.2 mm), 1/4" (≈6.35 mm), 3/8" (≈9.5 mm), 1/2" (≈12.7 mm) — or metric M20×1.5 thread, while the compression end accommodates tubing outer diameters of 6 mm (≈1/4"), 8 mm (≈5/16"), 10 mm (≈3/8"), 12 mm (≈1/2"), 14 mm (≈9/16"), or 16 mm (≈5/8"). Available in quantities of 1, 3, 5, or 10 pieces per order.
Typical applications include connecting stainless tubing to valve bodies or manifold ports in pneumatic control panels, joining water supply lines to equipment inlets in food and beverage processing, and building custom instrumentation tubing runs where a straight in-line stainless steel compression coupling is the cleanest solution.
🔗 Compatibility: Female threaded end fits NPT ports (1/8", 1/4", 3/8", 1/2") and M20×1.5 metric ports. Compression end accepts tubing OD of 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, or 16 mm. Select the variant that matches both your port thread and your tubing outer diameter.
⚠️ Verify both dimensions before ordering. The size designation on each variant shows thread size × tubing OD (e.g., "1/4 × 8mm" means a 1/4" female thread port with an 8 mm OD tube insert). Ordering the wrong insert depth is the most common sizing mistake — measure your tubing OD with calipers before selecting.
✅ Key Features of These 304 Stainless Steel Compression Fittings
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🔩Ferrule Compression Seal — The compression mechanism bites into the tubing OD to create a mechanically locked, leak-resistant joint without thread sealant on the tube end — ideal for stainless steel compression fitting pneumatic and hydraulic applications.
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🛡️304 Stainless Steel Body — Resists rust, moisture, and mild chemical exposure, making these couplings suitable for water, food-grade fluid, and outdoor instrumentation line applications where carbon steel fittings would corrode.
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📐Dual-Standard Thread Options — Available in both NPT fractional inch (1/8" through 1/2") and M20×1.5 metric thread, covering the most common port standards found in North American and internationally sourced equipment.
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📏Six Insert Depth Choices — Tubing OD options from 6 mm to 16 mm in 2 mm increments let you match the fitting precisely to your tubing without reducers or adapters, keeping your female straight coupling installation clean and compact.
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⚙️Straight In-Line Design — The female straight coupling geometry maintains a direct flow path with no bends, minimizing pressure drop across the connection — important in flow-sensitive pneumatic and fluid control systems.
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📦Flexible Pack Quantities — Order 1, 3, 5, or 10 pieces to suit single-point repairs or multi-connection panel builds, with per-unit cost decreasing at higher quantities.
📐 Technical Specifications — 304 Stainless Steel Compression Fitting Female Straight Coupling
| Material |
304 Stainless Steel |
| Fitting Type |
Female Straight Coupling Compression Connector |
| Thread End Options |
1/8" NPT, 1/4" NPT, 3/8" NPT, 1/2" NPT, M20×1.5 (metric) |
| Tubing OD (Insert Depth) Options |
6 mm (≈1/4"), 8 mm (≈5/16"), 10 mm (≈3/8"), 12 mm (≈1/2"), 14 mm (≈9/16"), 16 mm (≈5/8") |
| Seal Type |
Ferrule compression (no sealant required on tube end) |
| Finish |
Natural 304 stainless (mill finish) |
| Pressure Rating |
Contact us to confirm — varies by size and tubing wall thickness |
| Temperature Range |
Generally suitable for -20°F to 800°F (-29°C to 427°C) — confirm for your application |
| Compatible Thread Standards |
NPT (ANSI/ASME B1.20.1) and M20×1.5 metric |
| Quantity per Order |
1 Pcs / 3 Pcs / 5 Pcs / 10 Pcs (select above) |
| Country of Origin |
See variant options |
❓ Frequently Asked Questions
How do I choose the right compression fitting size for my tubing?
Match the thread size to your female port (e.g., 1/4" NPT or M20×1.5) and the insert depth to your tubing outer diameter. For example, a "1/4 × 6mm" fitting is generally used with 6 mm OD tubing inserted into a 1/4" female threaded port. Measure your tubing OD with calipers and check your port thread markings before selecting a variant.
How strong is a 304 stainless steel compression fitting connection?
304 stainless steel compression fittings are typically rated for moderate to high working pressures depending on tubing size and wall thickness. The ferrule-based compression mechanism creates a mechanically strong, vibration-resistant seal. Always verify the pressure rating against your system specifications for critical or high-pressure applications.
Can these compression fittings be used outdoors or in wet environments?
Yes. 304 stainless steel offers solid resistance to atmospheric corrosion, moisture, and many mild chemicals, making these fittings generally suitable for outdoor plumbing, irrigation systems, and food-grade fluid lines. For highly aggressive chloride or acidic environments — such as coastal saltwater exposure — 316 stainless steel is typically recommended instead.
What thread standards are used — NPT or metric?
These fittings are available in both fractional inch NPT sizes (1/8", 1/4", 3/8", 1/2") and metric thread (M20×1.5). The insert depth dimension (6 mm through 16 mm) refers to the tubing outer diameter that inserts into the compression end. Select the variant that matches both your port thread standard and your tubing OD — these are two separate dimensions.
Do I need thread sealant with these fittings?
For the threaded female port connection, applying PTFE thread tape or pipe thread sealant is generally recommended to ensure a leak-free seal in pressurized liquid or gas systems. The compression end seals mechanically via the ferrule and does not require additional sealant on the tube itself.
What is a female straight coupling compression fitting used for?
A female straight coupling compression fitting connects a length of tubing (inserted into the compression end) to a female-threaded port on a valve, manifold, or equipment body. It is commonly used in pneumatic control panels, hydraulic lines, water supply connections, and instrumentation tubing runs where a straight, in-line connection is needed without welding or flaring.
Can I reuse these compression fittings after disassembly?
Stainless steel compression fittings can generally be disassembled and reassembled a limited number of times. However, once a ferrule has been fully compressed onto tubing, it is typically deformed to that specific tube and may not seal as reliably on a different tube. For critical applications, using a new ferrule after disassembly is recommended.
🛒 Select your size and quantity above, then add to cart — ships from our US warehouse.
