Flexible Stainless Steel Tube Brazing with Brass Welding Wire | Low Deformation & Cost-Effective Solution

1. Process Overview

Flexible stainless steel corrugated tubes are widely used in HVAC, industrial gas systems, plumbing and mechanical

equipment connections. Thanks to their thin-wall and flexible corrugated structure, they absorb vibration and fit complex

installation layouts.

However, traditional fusion welding and TIG welding easily cause common defects including tube burn-through, corrugation

collapse, loss of flexibility and joint leakage, due to excessive heat input.

Our professional brass brazing process solves these problems perfectly. Using dedicated brass welding wire for flexible

stainless steel, we adopt low-temperature capillary brazing instead of high-temperature fusion welding. The process does not

melt the stainless steel base material, preserves the original flexibility of the tube, and delivers strong, leak-proof joints with excellent consistency and cost efficiency.

2. Core Advantages

Our optimized brazing process is specially developed for thin-wall flexible stainless tubes, with four key technical and

commercial benefits:

• No Deformation, Full Flexibility Retention

Brazing is performed at a low temperature, far below the melting point of stainless steel. Heat is strictly limited to the sleeve

joint area without heating the corrugated flexible section. This completely avoids softening, collapsing or structural damage,

ensuring the tubes retain full bending and vibration compensation performance

after welding.

• Superior Sealing Performance

We control precise assembly clearance to enable full capillary penetration of the brazing material. The filler metal uniformly

fills the entire joint gap to form a dense, void-free brazed fillet. No porosity, no cold joints, and zero leakage risk for long-term operation.

• Excellent Cost Advantage Under High Copper Price Conditions

With continuous high copper and silver material prices worldwide, traditional silver brazing greatly increases production

costs and compresses profit margins. Our dedicated brass welding wire provides stable and reliable joint quality equivalent to

standard silver brazing in normal working conditions, while reducing welding material costs by 30%–60%. It is the most

cost-effective mass production solution for the current high raw material price environment.

• High Stability & High Yield Rate

We implement a standardized full-process workflow including surface polishing, precise flux application, controlled heating

and professional post-wash treatment. The optimized low-heat welding method eliminates burn-through and deformation issues.

The finished product yield rate stably reaches over 99%.

3. Practical Project Case

Project Background

A professional HVAC equipment manufacturer produces flexible stainless steel piping systems for commercial central air

conditioning. The product adopts 0.3–0.5 mm thin-wall 304 stainless corrugated tubes, which require vibration resistance,

displacement tolerance and zero leakage during long-term service.

The customer’s original silver brazing and fusion welding processes suffered from high defect rates (over 30% rework) due

to tube deformation and micro-leakage. Meanwhile, rising copper and silver raw material prices further raised production costs,

creating an urgent need for a stable, low-cost and mass-producible welding solution.

Customized Solution

We delivered a customized brass brazing process for mass production of thin-wall flexible tubes:

• Material Matching: Adopted flexible stainless steel dedicated brass welding wire together with professional stainless steel

brazing flux to ensure stable flow, effective anti-oxidation and dense joint formation.

• Standard Sleeve Joint Design: Controlled insertion depth and precise assembly clearance to guarantee optimal capillary

brazing effect and consistent joint strength.

• Precision Localized Heating: Heat was only applied to the stainless steel sleeve area, keeping the corrugated flexible

section completely unaffected. Short-time constant-temperature heating avoided local overheating and tube deformation.

• Professional Post-Welding Treatment: Natural cooling prevented thermal cracking. Residual flux was thoroughly cleaned

with high-temperature water to avoid later corrosion and extend service life.

Project Result

In this batch production of more than 3,200 flexible stainless steel tubes, zero burn-through, zero deformation and

zero flexibility loss were recorded. All finished products passed strict air and hydraulic pressure tests: stable at 0.8 MPa for 30 minutes  with no pressure drop or leakage, fully meeting commercial HVAC long-term operation standards.

After adopting our process, the customer’s rework rate dropped from 30% to below 0.5%, and overall production efficiency

increased by 40%. Benefiting from our cost-optimized brazing solution, the customer achieved substantial cost savings in welding

materials and rework losses under high copper price conditions, greatly improving product profitability and market

competitiveness. The solution has become the customer’s standard mass production process.

4. Application Scope

This brass brazing solution is ideal for all types of thin-wall flexible stainless steel corrugated tubes, widely applied in HVAC

water systems, low-pressure industrial gas pipelines, mechanical equipment flexible connections, kitchen and bathroom

plumbing, and automation equipment buffer pipelines.

For high-pressure, strong corrosion and high-frequency vibration working conditions, we provide upgraded silver brazing

solutions to meet customized high-standard requirements.

5. Our Service

We have rich experience in dissimilar metal brazing and thin-wall flexible tube welding. We support sample testing, small-

batch trial production and large-scale mass customization. Strict standardized process control ensures stable quality and reliable

consistency. Test reports and pressure test data can be provided upon request.

Contact us for professional process consultation, custom solutions and bulk cooperation!