Research On The Replacement Of Seamless Titanium Tubes With Welded Titanium Tubes
Aug 13, 2025
Titanium has the characteristics of low density, high specific strength, corrosion resistance, high elasticity, low damping, non-magnetic and good high and low temperature performance. It is known as "space metal" and "ocean metal" and is widely used in many national economic and national defense construction fields such as aerospace, seawater desalination, shipbuilding, chemical industry, automobile, electricity, etc. Due to the low yield rate, long production cycle and high cost of seamless tubes, and the short production process, low production cost and high production efficiency of pure titanium welded tubes, vigorously developing thin-walled welded tubes has become a trend in today's tube production. In Japan, Europe and the United States, titanium and titanium alloy thin-walled seamless tubes are gradually being replaced by titanium welded tubes and are used in condensers and condensers in coastal power stations and nuclear power plants, which not only improves the heat exchange efficiency, but also increases the service life of condenser and condenser units, with significant economic benefits.
When welding titanium tubes, it must be ensured that:
(1) The metal in the welding area is not contaminated by active gases N, O, H and harmful impurity elements C, Fe, Mn, etc. above 250℃.
(2) Coarse grain structure cannot be formed.
(3) Large welding residual stress and residual deformation cannot be generated. Therefore, the welding process must be carried out according to the predetermined construction sequence and strictly in accordance with the process quality management standards, and quality control must be implemented throughout the process. All factors, including people, machines, materials, and methods, are under good control, thereby ensuring the welding quality of the titanium tube within a reasonable construction period.
The bursting pressure of the titanium welded tube is 61.76MPa. A small crack appeared at the longitudinal weld of the titanium welded tube, and the water in the tube burst out from the weld. Seamless titanium tube: The bursting pressure is 68.10MPa. A large crack appeared at the connection of the tube with the plug during the pressure test. The water in the tube burst out from the connection between the tube and the plug, and the seamless tube itself was not damaged. During the use of titanium tube heat exchangers, condensers, and steam condensers, the vibrations induced by the shell-side fluid cause vortexes, buffeting, elastic excitation, and acoustic resonance of different fluids. These oscillations combine to form violent vibrations, which cause the tubes to continuously hit the baffles, resulting in the tubes being cut and penetrated by the baffle edges, and the connection between the tube and the tube sheet being torn and leaking. Therefore, fatigue vibration tests were conducted on titanium welded tubes and titanium seamless tubes, and the fatigue times of titanium welded tubes and titanium seamless tubes under the same conditions were counted to determine whether replacing titanium seamless tubes with titanium welded tubes would affect the service life of the equipment.
(1) Expansion properties of welded titanium tubes: Under the same expansion pressure, the pull-off force of welded titanium tubes is 2.5-3.1MPa greater than that of seamless titanium tubes. After expansion, the welded titanium tubes are more tightly combined with the expansion tooling, and the expansion sealing is better.
(2) Welded titanium tubes can withstand the maximum design pressure of 35MPa within the defined range of pressure vessels and maintain pressure for 3 minutes without leakage.
(3) Titanium welded pipes and titanium seamless pipes at a frequency of 30.
The principles and processes for rolling titanium pipes are the same as those for seamless titanium pipes. However, the presence of weld beads requires consideration of additional factors in order to determine the best and most stable rolling process. Among these factors, the most important are the metallurgical quality and surface condition of the pipe. For example, it is desirable to use pipes in the annealed state rather than the welded state. For tight-fit connections in tube-sheet designs, excessively protruding filler beads must be avoided. It has been proven that the bonding strength of air-annealed expanded pipes with polished heads is better than that of pipes expanded in the bright annealed or bright stress-relief annealed state. On the other hand, a rough tube surface or tube-sheet surface can improve mechanical strength, but poor sealing. The surface finish of titanium tube-sheet holes manufactured by precision machining or machining plus reaming tube-sheet holes is 0.75-1.5-101, and the finish of the tube-sheet polished ring is also at the same level, so that strength and sealing can be optimally matched.
The company boasts leading domestic titanium processing production lines, including:
German-imported precision titanium tube production line (annual production capacity: 30,000 tons);
Japanese-technology titanium foil rolling line (thinnest to 6μm);
Fully automated titanium rod continuous extrusion line;
Intelligent titanium plate and strip finishing mill;
The MES system enables digital control and management of the entire production process, achieving product dimensional accuracy of ±0.01μm.
