Compression tube fittings
Compression tube fittings provide a reliable, flareless method of joining stainless steel tubing without welding or soldering. Each fitting is built on a two-ferrule (front and back ferrule) design housed in a body and secured with a nut. When the nut is tightened, the ferrules compress and grip the tube outer diameter, forming a leak-tight metal-to-metal seal that accommodates tolerances in tube OD, wall thickness, and material hardness. This design allows for easy installation, tool-free disassembly and remaking of joints, and dependable performance under high pressure, vibration, and thermal cycling, making the fittings suitable for instrumentation, process, and utility tubing systems across marine and industrial installations.
Description
Compression tube fittings provide a reliable, flareless method of joining stainless steel tubing without welding or soldering. Each fitting is built on a two-ferrule (front and back ferrule) design housed in a body and secured with a nut. When the nut is tightened, the ferrules compress and grip the tube outer diameter, forming a leak-tight metal-to-metal seal that accommodates tolerances in tube OD, wall thickness, and material hardness. This design allows for easy installation, tool-free disassembly and remaking of joints, and dependable performance under high pressure, vibration, and thermal cycling, making the fittings suitable for instrumentation, process, and utility tubing systems across marine and industrial installations.
Features
Two-ferrule (double ferrule) design compensates for tube OD, wall thickness and hardness variation
No tube flaring required prior to installation
Leak-tight metal-to-metal seal under pressure, vibration and thermal cycling
Tool-free disassembly and remake without loss of sealing integrity
Wide size range covering fractional and metric tubing
Available in tube unions, male/female connectors, bulkhead unions, tees, elbows, reducers, nuts, ferrules and plugs
Constructed from corrosion-resistant stainless steel bar stock and forged material
Compatible with standard and hydraulic swaging installation tools
Suitable for hazardous, high-pressure and cryogenic service conditions
Heat-code traceability for material certification and quality assurance
Specifications
| Product Type | Compression Tube Fittings (Two-Ferrule / Double Ferrule Design) |
| Construction | Body, front ferrule, back ferrule, and nut (four-piece assembly) |
| Material | Stainless Steel (typically 316 / 316L SS) |
| Fitting Range | Tube unions, male connectors, female connectors, bulkhead unions, tees, elbows, reducers, nuts, ferrules and plugs |
| Tube Size Range | 1/16" to 2" O.D. (metric equivalents available, 2 mm to 38 mm O.D.) |
| End Connections | Tube-to-tube, tube-to-male pipe (NPT/BSP), tube-to-female pipe, bulkhead-mounted |
| Sealing Method | Metal-to-metal, two-ferrule compression seal (no flaring required) |
| Applicable Standards | ASTM A276 / ASTM A479 / ASME SA479 (bar stock), ASTM A182 / ASME SA182 (forged fittings), ASTM F1387 (dimensional/performance) |
| Assembly | Field-installable with standard or hydraulic swaging tools; remake-capable |
Technical Specifications
| Parameter | Specification |
|---|---|
| Fitting System | Two-ferrule (double ferrule) compression design |
| Body, front ferrule, back ferrule, nut | Components |
| Material Grade | 316 / 316L Stainless Steel (other alloys available on request) |
| Bar Stock Standard | ASTM A276, ASTM A479, ASME SA479, JIS G4303 |
| Forged Fitting Standard | ASTM A182, ASME SA182, JIS G3214 |
| Tube OD Range | 1/16" – 2" (2 mm – 38 mm) |
| Pressure Rating | Rated to maximum working pressure of the connecting tubing |
| Suitable for cryogenic through high-temperature service (application-dependent) | Temperature Range |
| Tube-to-tube, male NPT/BSP, female NPT/BSP, bulkhead | End Connection Types |
| Front ferrule forms primary seal at body; back ferrule grips and anchors tubing | Sealing Principle |
| Disassembly | Nut can be backed off and remade without damaging seal integrity |
| Heat-code traceable material certification available | Traceability |
Applications
Available Configurations
Tube Unions
Straight connections joining two lengths of tube of the same or different outer diameters, used to extend or connect tubing runs.
Male / Female Connectors
Adapters joining tubing to male or female NPT/BSP threaded ports on valves, instruments, and equipment.
Bulkhead Unions
Fittings designed to pass tubing through a panel or bulkhead while maintaining a leak-tight seal on both sides.
Tees and Elbows
Branch and directional fittings used to split or redirect tubing runs within a system.
Reducers
Fittings connecting tubing of two different outer diameters within the same line.
Nuts, Ferrules and Plugs
Individual components and spares, including front/back ferrule sets, nuts, and port plugs, for fitting assembly, maintenance, and replacement.
Benefits
Typical System Components
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