High density, high corrosion resistance, high elasticity, low damping, non-magnetic and high and low temperature performance, known as "space metal", "marine metal", widely used in aerospace, desalination, ship , Chemical, automotive, power and many other national economic and national defense construction. Due to the low yield of seamless pipe, long production cycle and high cost, the production process of pure titanium pipe is short, the production cost is low, the production efficiency is high, and the development of thin-walled pipe becomes a trend of pipe production. In Japan, Europe, the United States, titanium and titanium alloy thin-walled seamless pipe is gradually replaced by titanium pipe, used in coastal power plants and nuclear power plants in the condenser and condenser, not only improve the heat exchange efficiency, but also improve the condenser And the life of the condenser unit, significant economic benefits.
Titanium tube welding must ensure the following issues:
(1) the welding area of the metal at 250 ℃ above the active gas N, 0, H and harmful impurities such as C, Fe, Mn and other pollution.
(2) can not form coarse grain structure.
(3) can not produce a large welding residual stress and residual deformation. Therefore, the welding process to be in accordance with the scheduled construction sequence, in strict accordance with the process of quality management standards, the implementation of the whole process of quality control. So that people, machines, materials, France, the factors are in a well-controlled state, which in a reasonable period of time to ensure the quality of titanium tube welding.
Titanium pipe burst pressure of 61.76MPa, titanium welded pipe longitudinal weld there is a small crack, the tube of water from the weld burst out. Seamless titanium tube: burst pressure of 68.10MPa, pipe pressure test plug connection at the junction of a larger crack, the pipe from the pipe and plug the Department of blasting out, seamless tube itself did not damage. Titanium tube heat exchangers, condensers, condensers, etc. in the course of the process due to shell-induced fluid induced vibration, causing different fluid vortex, chattering, elastic excitation and acoustic resonance, the combination of these oscillations to form a violent vibration , Resulting in the tube constantly hit the baffle, resulting in the pipe by the edge of the baffle cutting through the pipe and tube plate at the junction was pulled to the occurrence of leakage and so on. Therefore, the fatigue test of titanium tube and titanium seamless pipe is carried out, and the fatigue times of titanium pipe and titanium seamless pipe under the same conditions are calculated to determine whether the titanium alloy pipe is used instead of titanium seamless pipe.
(1) welding titanium tube expansion of the same: the same expansion of the pressure of the case, the welding titanium tube pulling force than the seamless titanium tube pulling force 2.5-3.1MPa, welding titanium tube expansion and expansion after the combination of tooling More closely, inflated closed better.
(2) welding titanium tube can withstand the pressure vessel within the definition of the maximum design pressure of 35MPa, holding pressure 3min without leakage.
(3) Titanium and titanium seamless tubes at a frequency of 30.
Welding titanium tube roller up the principle and process and no titanium tube is the same. However, the presence of beads requires consideration of additional factors in order to determine the best and stable roll up process. Among these factors, the most important is the metallurgical quality of the pipe and the surface state. For example, pipes that wish to be in an annealed state rather than a welded state must be used to avoid excessive protrusion of the bead for the tight fit of the tube design. It has been shown that the air annealed head has a flared flare Of the bonding strength than in the bright annealing or bright stress to eliminate the state of the expansion of the pipe to be better. On the other hand, the rough tube surface or tube sheet surface can improve the mechanical strength, but the sealing is poor. The surface finish of titanium tube plate made by precision machining or machining plus hinge plate hole is 0.75-1.5-101, and the finish level of finish of pipe head has reached the same level, so that the strength and sealing can achieve the best fit.
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