Industrial piping systems are often exposed to operating conditions that exceed the practical limits of conventional elastomeric connections.
High-temperature steam, thermal fluids, hot gases, and pressurized process media can impose simultaneous thermal, mechanical, and pressure loads on flexible piping components.
When operating temperatures move beyond the suitable range of rubber, a metal bellows hose with stainless steel reinforcement provides a fundamentally different solution.
When rubber reaches its temperature limit, engineered metal flexibility becomes the next line of defense.
Elastomeric expansion joints offer excellent flexibility and vibration isolation in water and moderate-temperature applications.
However, their temperature capability is material-dependent.
Many conventional rubber compounds are not suitable for sustained service at temperatures above approximately 120°C, although the actual limit varies significantly with elastomer type, pressure, medium, reinforcement, and operating conditions.
At excessive temperatures, elastomers can experience:
Accelerated aging
Hardening or softening
Loss of elasticity
Compression-set deterioration
Cracking
Reduced fatigue resistance
Progressive loss of sealing performance
For high-temperature services such as steam, thermal oil, and hot process gases, metallic flexible elements are therefore often more appropriate.
Stainless steel bellows hoses can be engineered for a much wider temperature range, with selected configurations capable of service from approximately -196°C to +400°C or beyond, depending on material, construction, pressure, end fittings, and application conditions.
A corrugated metal tube provides excellent flexibility, but internal pressure generates circumferential and longitudinal forces within the hose assembly.
Without suitable pressure reinforcement, the bellows may experience excessive axial movement or deformation.
This is where the stainless steel braid becomes critical.
The external braided sleeve acts as a pressure-restraining reinforcement layer, helping control pressure-induced hose elongation and stabilizing the corrugated tube during operation.
Depending on the hose diameter, bellows construction, braid configuration, material, and end fittings, B-NAI assemblies can be designed for working pressures up to 40 bar or higher.
The exact pressure rating must always be established from the complete hose assembly rather than the bellows or braid alone.
B-NAI metal braided hoses combine a flexible corrugated stainless steel bellows with a high-density stainless steel braided sleeve.
The result is a flexible pressure-containing assembly capable of handling thermal movement, equipment vibration, installation displacement, and demanding industrial service conditions.
Corrugated Metal Bellows
Provides the primary fluid containment and flexible movement capability.
Stainless Steel Braided Sleeve
Restrains pressure-induced elongation and provides mechanical reinforcement.
End Fittings
Transfer mechanical loads into the connected piping or equipment.
Precision Welded Connections
Provide controlled and reliable joints between the bellows, braid collars, and end fittings.
B-NAI metal hoses use precision-formed stainless steel corrugated tubes designed to combine flexibility with structural stability.
Hydroforming provides controlled corrugation geometry and consistent manufacturing quality across the bellows profile.
The corrugated structure allows the hose to flex repeatedly while accommodating:
Axial compression
Axial extension
Lateral movement
Angular deflection
Mechanical vibration
Thermal movement
The bellows geometry is engineered to distribute deformation across multiple convolutions rather than concentrating movement at a single point.
This is particularly important in applications involving repeated thermal cycles or continuous mechanical vibration.
The stainless steel braid is manufactured from multiple strands of high-strength stainless steel wire woven into a dense mesh structure.
Its primary functions include:
Restricting pressure-induced axial elongation
Stabilizing the bellows during operation
Increasing assembly pressure capability
Providing additional mechanical protection
Transferring pressure reaction forces toward the end fittings
The braid is not the primary fluid containment barrier.
The corrugated bellows contains the medium; the braided sleeve provides pressure restraint.
This distinction is essential when engineering a metal hose for high-pressure service.
A flexible hose is only as effective as its connection to the surrounding piping.
B-NAI metal braided hoses can be configured with different end connections according to the installation requirements.
Typical options include:
Carbon steel or stainless steel flanges can be configured for easier bolt-hole alignment and equipment connection.
Suitable for smaller-diameter equipment connections where a compact threaded interface is required.
Designed for permanent welded connections in industrial process piping.
Special flange dimensions, materials, and connection configurations can be developed according to project requirements.
The objective is simple: make the flexible hose fit the actual system — not force the system to fit a standard hose.
Metal hoses operating under thermal cycling and pressure require controlled manufacturing processes.
B-NAI production can incorporate precision TIG / argon-arc welding for critical metal joints, together with controlled cleaning and degreasing procedures.
For selected applications, components can be processed without conventional acid pickling where the specified manufacturing and surface-finish requirements call for an alternative cleaning process.
Key manufacturing controls may include:
Bellows dimensional inspection
Corrugation consistency
Weld quality inspection
Braid coverage inspection
End-fitting dimensional verification
Cleaning and degreasing
Pressure testing
Final assembly inspection
The exact inspection and testing program can be adapted to the project specification.
| Requirement | Rubber Expansion Joint | B-NAI Metal Braided Hose |
|---|---|---|
| High-temperature service | Application-dependent | Well suited |
| Steam service | Generally limited | Excellent potential |
| Thermal fluid | Application-dependent | Suitable with correct material |
| Vibration isolation | Excellent | Excellent |
| Axial movement | Available | Available |
| Lateral flexibility | Available | Available |
| Pressure restraint | Fabric reinforcement | Stainless steel braid |
| Corrosion resistance | Elastomer-dependent | Stainless-steel construction |
| Cryogenic service | Generally unsuitable | Selected configurations available |
| Compact routing | Good | Excellent |
| End fitting options | Mainly flanged | Flanged / threaded / welded |
| High-temperature cycling | Limited by elastomer | Strong potential with proper design |
The two products serve different operating envelopes.
Rubber provides high elasticity and damping. Metal provides high-temperature and high-pressure capability.
Selecting the correct flexible connection starts with the actual operating conditions.
B-NAI metal braided hoses are designed for industrial systems where conventional rubber flexible connections may not provide sufficient temperature capability.
Used around steam equipment, turbine auxiliary systems, boiler piping, and thermal expansion interfaces where high temperature and pressure are major design factors.
Suitable for selected process-fluid connections, loading manifolds, thermal-fluid lines, and equipment interfaces.
Applied where thermal cycling, equipment vibration, and piping movement occur simultaneously.
Used in selected hot-gas and exhaust applications where metallic flexibility is required.
Suitable for hot-oil and other thermal-fluid piping when the bellows material, braid, fittings, and sealing components are selected for the actual operating temperature.
| Parameter | Typical B-NAI Configuration |
|---|---|
| Product Type | Flexible Metal Hose with Braided Sleeve |
| Bellows Material | Stainless Steel 304 / 316 / Application-Specific Alloy |
| Braid Material | Stainless Steel 304 / 316 |
| Primary Pressure Boundary | Corrugated Metal Bellows |
| Reinforcement | High-Density Stainless Steel Wire Braid |
| Typical Pressure Range | Application-specific; selected designs up to 40 bar or higher |
| Temperature Range | Application-specific; selected configurations approximately -196°C to +400°C or beyond |
| End Connections | Flanged / Threaded / Weld Ends |
| Main Functions | Thermal Movement + Vibration + Flexible Connection |
| Manufacturing | Hydroforming / Precision Welding / Controlled Cleaning |
| Testing | Pressure / Dimensional / Weld & Assembly Inspection, as specified |
Important: Actual allowable pressure and temperature are determined by the complete assembly, including bellows material, diameter, wall thickness, braid construction, end fittings, welding method, movement cycle, and operating medium.
B-NAI metal braided hoses are designed as complete assemblies rather than treating the bellows, braid, and fittings as independent components.
Stainless steel and application-specific alloys can be selected according to temperature, medium, corrosion environment, and pressure requirements.
The woven braid provides controlled pressure restraint while preserving the flexibility of the bellows.
Flanged, threaded, welded, and customized end connections allow the hose to integrate with different equipment and piping systems.
Diameter, bellows construction, braid layers, end fittings, and overall length can be selected according to the actual installation.
Rubber expansion joints remain highly effective in water, HVAC, and moderate-temperature systems.
But every flexible connection has an operating envelope.
When temperature, pressure, and thermal cycling move beyond the practical range of elastomers, continuing to use rubber simply because it is flexible can create an unnecessary engineering limitation.
A stainless steel corrugated bellows provides flexibility through its geometry.
A stainless steel braid provides pressure restraint.
Together, they create a flexible metal connection engineered for demanding thermal and pressure conditions.
The right flexible connection is not the softest one.
It is the one designed for the actual operating environment.
To select the appropriate metal hose assembly, please provide:
Nominal Diameter (DN)
Hose Length
Operating Pressure
Operating Temperature
Fluid / Medium
Required Movement
Number of Flex Cycles
Flange Standard
End Connection Type
Bellows Material
Braid Material
Installation Orientation
Quantity
B-NAI can provide application-specific metal braided hose assemblies for steam, power generation, petrochemical processing, thermal-fluid systems, boiler equipment, and industrial process piping.
When elastomers reach their practical limits, engineered metal flexibility takes over.
B-NAI — Flexible Piping Solutions for Demanding Industrial Applications.
