Improve the life of titanium pipe fittings and become a major academic problem in the field of pipeline design technology.
Elbow extrusion process is in the mid and late eighties by Japan introduced into China's steel elbow production of a new technology. Because the process can achieve continuous production, and the production of elbow wall thickness uniformity, so it quickly replaced the traditional process. Northwest Nonferrous Metals Research Institute in the early nineties took the lead in this new technology successfully developed a seamless titanium elbow pushed. Successively developed a seamless titanium tee, seamless reducer and other seamless titanium pipe fittings products, seamless pipe fittings, the large diameter of up to Φ219, and reached the ASTMB363-95 standard requirements.
Push titanium elbow processing is a seamless titanium pipe as a billet, in the push extruder using a pipe diameter smaller than the finished caliber of the billet push extrusion molding, forming die is fixed in the host machine does not move, there is an active thrust to promote the billet from the right to the left, the billet in the forming die, subject to heating and protection, forming process billet is subjected to expansion, the forming process of the force analysis shows that the size of the force in different parts of the process is Different, but are two-way pressure, a tensile, that is, axial pressure, radial pressure, circumferential tension. Throughout the deformation process, the diameter gradually becomes larger, bending, length shortening but the thickness is basically unchanged. Experimental results with the network method confirmed that the deformation of the elbow forming mainly occurs in the lower part. Uniform grid drawn on the blank, moulding can be observed in the back of the elbow forming the square grid changes are not significant, to the belly of the more serious deformation, the grid in the periphery is elongated, axial compression, while the total area of the grid remains unchanged, indicating that there is no significant change in the direction of the thickness.
Titanium fittings standard appeared early in the U.S. aerospace standards, chemical industry titanium fittings in the international can find the only standard is ASTMB3635 it is also a titanium standard parts of international trade often follow the document, ASTMB363 was established in 1961, the first modification in 1978, and then many times (such as 83 years, 87 years) the recent version is 1995, so that the standard is more complete! The most recent version is 1995, which makes the standard more perfect.
China in 1994 by the Northwest Nonferrous Metals Research Institute developed a standard Q/XB1507-94 "titanium butt-welding seamless pipe fittings". Warmly welcomed by the design department, the standard on behalf of China's titanium pipe fittings standardisation of the start. Is China's titanium pipe fittings production, distribution, design, construction of the main reference documents.
In order to make the standard can better guide the standardised production of titanium pipe fittings, design selection, procurement and distribution, installation and construction, China's Petroleum and Chemical Industry Bureau on July 13, 1999 released the "titanium butt-welding seamless pipe fittings" industry standard, this standard drafted by the Northwest Nonferrous Metals Research Institute, the standard number HG/T3651-1999, has been implemented on June 1, 2000 onwards. The standard size tolerance of the fittings and the U.S. standard ANSIB16.9-1986 "forged steel butt-welded fittings" and China's standard GB12459-90 "steel butt-welded seamless fittings" and so on, fittings requirements and finished fittings and fittings material properties and surface quality of fittings and the U.S. Materials Testing Institute standard ASTMB363-95 "seamless and seam titanium and titanium alloy butt-welded fittings" and so on. Equivalent.
