Titanium has the characteristics of low density, high strength, corrosion resistance, and easy formation of droplet condensation on the surface. Since the 1980s, it has gradually been used to manufacture key components such as heat transfer tubes for power station condensers. The matching tube sheet is also replaced by the titanium steel composite tube sheet from the original 25~35mm thick pure titanium sheet, which saves rare metals and reduces manufacturing costs.
Titanium-steel clad tube sheet is a bimetal clad sheet made of carbon steel as the base layer and industrial pure titanium as the cladding layer by explosion, rolling, and other methods. The base layer of the titanium steel clad plate mainly meets the strength and stiffness requirements of the welded structure design, while the cladding layer meets the requirements of special properties such as corrosion resistance.
1. Causes of defects in titanium steel composite tube sheet
The titanium-steel clad plate produced by the explosive composite method has both the corrosion resistance of titanium and the strength and plasticity of ordinary steel plates as structural parts. It is particularly important that the cost is greatly reduced, so it is widely used in various chemical reaction vessels. , heat exchanger materials, and anti-corrosion fields. A large number of titanium-steel composite plates are used to manufacture tube sheets of steam turbine condensers. Due to a large number of holes in a single tube sheet (up to more than 20,000), the number of tube sheets that can be drilled and reamed at one time on a CNC drilling machine is limited. At present, there are still some tube sheet holes processed according to the process of CNC machine tool scribing + radial drilling machine drilling and reaming. Since the radial drilling machine is manually operated, the processing quality of the pipe hole is greatly affected by human factors; some operators damage the titanium surface during the feeding or lifting of the radial drilling machine, resulting in the lack of meat in the titanium layer, which makes the quality of subsequent expanded and welded pipes is difficult to guarantee.
2. The possible impact of defects
The welding of the pipe hole is to seal the pipe mouth to prevent leakage. Defects such as pits, flanging, and oxidation appear at the weld. Since the welding of the tube and the tube sheet is self-fusion welding without filler wire, the weld is completely filled by the extension of the molten titanium tube. Therefore, the weld metal first fills the gap of the titanium layer during welding, resulting in the appearance of the weld. pits. At the same time, due to the lack of meat in the titanium layer of the tube sheet, after the tube is expanded, it is easy to have a gap where the tube mouth is not in place, and a large amount of air remains in this gap and cannot be discharged. During welding, the arc deviates from the titanium tube and the influence of residual air, so the titanium tube flanging and weld oxidation.
The tube sheet with a lack of flesh in the titanium layer cannot be used. The lack of flesh in the titanium layer will seriously affect the expansion and welding quality of the tube sheet and reduce the overall quality of the steam turbine condenser. Therefore, the titanium-steel composite tube sheet must be eliminated by repairing the titanium layer. Defects. At this time, we can repair the defects by welding.
If you are looking for a professional titanium steel clad tube sheet manufacturer, Baoji Taicheng Clad Metal Materials Co., Ltd is your best choice. Our company has many years of operating and sales experience in the industry. Whether it is product quality or pre-sales and after-sales service, we can guarantee the best. Looking forward to working with you!
