Improving the life of titanium pipe fittings has become a major academic problem in the field of pipeline design technology.
The elbow-pushing process is a new technology for the production of steel elbows introduced by Japan in the middle and late 1980s. Because the process can achieve continuous production and produce elbows with uniform wall thickness, it quickly replaced the traditional process. Northwest Institute of Nonferrous Metals took the lead in successfully developing this new technology in the early 1990s to develop a push seamless titanium elbow. We have successively developed seamless titanium pipe fittings such as seamless titanium tees, seamless reducers, etc. The largest diameter of seamless pipe fittings can reach Φ219 and meet the requirements of ASTM B363-95 standard.
The processing of the pushed titanium elbow is based on the seamless titanium tube as the billet, and the billet with a diameter smaller than the finished product is used to push and extrude the billet on the push extruder. The forming die is fixed on the main machine and there is a movable thrust to push the tube. The billet advances from the right to the left. The billet is heated and protected when forming the mold. The tube blank is expanded during the forming process. The analysis of the force during the forming process shows that the stress on different parts is different, but they are all Two-way compression, and one-way tension, that is, axial compression, radial compression, and circumferential tension.
During the whole deformation process, the diameter gradually increases, bends, and the length shortens while the thickness remains basically unchanged. The experimental results using the network method confirm that the deformation of the elbow during forming mainly occurs in the lower part. Draw a uniform grid on the blank. It can be observed that the grid changes little when forming the back of the elbow. When the deformation of the abdomen becomes more serious, the grid is elongated around and compressed in the axial direction, while the total area of the grid remains unchanged. , indicating that there is no significant change in the thickness direction.
Standards and specifications for titanium pipe fittings in our country
Titanium pipe fittings standards first appeared in American aerospace standards. The only international standard for titanium pipe fittings in the chemical industry is ASTMB3635, which is also a document often followed in the international trade of titanium standard parts. ASTMB363 was established in 1961, and the first revision was In 1978, it was revised many times later (such as in 1983, 1987). The most recent version was in 1995, which made the standard relatively complete.
In 1994, my country formulated the standard Q/XB1507-94 "Titanium Butt Welding Seamless Pipe Fittings" by the Northwest Institute of Nonferrous Metals. It has been warmly welcomed by the design department, and this standard represents the start of the standardization of titanium pipe fittings in my country. It is the main reference document for the production, distribution, design, and construction of titanium pipe fittings in my country.
In order to make the standard better guide the standardized production, design, and selection, procurement and distribution, installation, and construction of titanium pipe fittings in my country, my country Petroleum and Chemical Industry Bureau issued the "Titanium Butt Welding Seamless Pipe Fittings" industry standard on July 13, 1999. Standard, this standard was drafted by Northwest Nonferrous Metals Research Institute, the standard number is HG/T3651-1999, and it has been implemented since June 1, 2000. The dimensional tolerances of pipe fittings stipulated in this standard are the same as the American Standard ANSIB16.9-1986 "Forged Steel Butt Welding Fittings" and the
Chinese standard GB12459-90 "Steel Butt Welding Seamless Pipe Fittings". The surface quality of the pipe fittings is equivalent to the American Society for Testing and Materials standard ASTMB363-95 "Seamless and Seamed Titanium and Titanium Alloy Butt Welding Pipe Fittings".
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