Stainless Steel Compression Fittings — Straight & Reducing Connectors, Φ3mm–Φ25mm

Measure the outer diameter (OD) of your tubing with calipers — do not use the inner diameter or nominal size. The bore size listed (e.g., Φ6mm) is the tube OD the fitting accepts. For reducing connectors (e.g., Φ10mm–Φ6mm), the first number is the larger-end tube OD and the second is the smaller-end tube OD. As a reference: a 1/4" tube is typically ≈6.35mm OD, a 3/8" tube is typically ≈9.5mm OD, and a 1/2" tube is typically ≈12.7mm OD.

Straight connectors are available in matching bore sizes from Φ3mm through Φ25mm (approximately 1/8" to 1"). Reducing connectors cover common step-down combinations including Φ6×4mm, Φ8×6mm, Φ10×6mm, Φ10×8mm, Φ12×6mm, Φ12×8mm, Φ12×10mm, Φ14×12mm, Φ16×12mm, and Φ16×14mm. Select your bore size from the dropdown above.

Stainless steel compression fittings are generally rated for working pressures up to 150–300 PSI depending on tube size and wall thickness — typically stronger than brass or plastic alternatives. They maintain their rated strength across a wide temperature range. If you need exact pressure ratings for a specific bore size, contact us before ordering.

Yes. Stainless steel offers significantly better corrosion resistance than carbon steel or brass in most outdoor, marine-adjacent, and humid environments. For highly aggressive chemical exposure (strong acids, chlorides at high concentration), contact us to confirm material compatibility before ordering.

These compression fittings are generally compatible with rigid and semi-rigid tubing including copper, stainless steel, aluminum, and nylon tubing. They are not typically recommended for very soft or thin-walled plastic tubing without a support insert sleeve. Always match the fitting bore to your tube's outer diameter.

Compression fittings create a mechanical seal by compressing a ferrule against the tube — no sealant is needed for the tube connection itself. However, if the fitting body threads into a port or adapter, applying PTFE tape to those external threads is generally recommended to prevent leaks at that threaded joint.

Each listing offers 1 pc, 2 pcs, or 5 pcs options. Select your preferred quantity from the Amount option above. Multi-piece packs offer a lower per-unit cost and are useful for projects requiring multiple connection points or for keeping spares on hand.

Compression fittings can generally be disassembled and reassembled a limited number of times. In most cases, the ferrule deforms slightly during initial installation and may not re-seal as reliably on a different tube. For critical pressure applications, replacing the ferrule or the full fitting after disassembly is recommended.