Distinctive Characteristics of Dong-A Corrugated Stainless Steel Tube

Dong-A keeps welding bead width of stainless steel tube less than 0.7mm, so that thickness of welding bead can stay the same as thickness of the parent material.

Also, we make the corrugated stainless steel tube with minimum Slip Band Martensite of the metal structures that happens during the corrugation forming under the optimum condition after locally applying heat treatment to the weld bead and heat affected area.

As the forming of the corrugated stainless steel tubes are conducted from external to internal (center line), the width of the valley area is inevitably thin. Then, the thinned area is mostly affected by the metal fatigue during vibration or vending expansion-contraction or banding, which creates crack corrosion and decreases its life span. Against this backdrop, while it applies the buckling forming (distortion forming) to supplement its weakness, corrugated tube is formed at the temperature condition to minimize cold work hardening of the austenite stainless steel. Hence, the corrugated tubes manufactured by Dong-A are the most advanced ones by minimizing the thickness change ratio of the peak and valley, and work hardening

As corrugated stainless steel generates huge amount of work hardening during the forming process, the degree of hardness is increased more than 50% and create the Slip band Martensite. Then, the physical disposition and anti-corrosiveness of stainless steel become weak, so that it is necessary to conduct Solution Heat Treatment except for special usage.

The existing solid solution heat treatment method has inevitably uneven heat treatment effects because the cooling water temperature may be changed due to the seasonal change, the variability in daily temperature, and the heat capacity of the treated materials.

The corrugated tubes manufactured by Dong-A is automatically controlled its cooling water temperature using the freezing machine, which maintains the set temperature evenly regardless of the external conditions and allows its stable heat treatment effects (standardizing the effects of heat treatment)

In case of welded joints, brazing welding of the fitting (of Dong-A’s stainless steel flexible joint) is done at the same time during the solution heat treatment for the flexible tube in the solution heat treatment furnace. As a result, it has new technology (NEP) to prevent corrosion by welding stresses. And in case of the screw connection method at the joint, it provides an excellent sealing effect and anti-corrosiveness by using the insulated and durable materials, with simple sealing structure

Dong-A is ready to meet customer’s demand of product with any specification in stainless steel, copper, aluminum, with our world top class technologies, facilities, and test devices conforming to the standards of Germany, U.S.A. and Japan.

We offer Coefficient measurement of hydrodynamic friction loss and the Moody Chart for Dong-A product.