At present at home and abroad has been used in a structure of pipe connection, that is, the bayonet pipe joint connection method. In 1983, the national bureau of standards issued the universal standard for card and socket connection. There are many types of sleeve connection, such as squeeze type, expansion type, self-support type, bite type, etc. According to the standards issued by the national bureau of standards, the clamp-sleeve connection in China belongs to squeeze type and bite type, and its structure consists of three parts: the connector body, clamp-sleeve and nut. One of the key components is the sleeve - a metal ring with a cutting edge (the sleeve for indoor hot water heating is rubber).
Through the research on the domestic bayonet type pipe joint, it is found that the domestic bayonet type pipe joint has the following defects.
青海快31。 The bayonet pipe joint is out of date
China's current standard of sleeve type pipe joint is still the standard implemented more than ten years ago. Foreign bayonet tube joint has been updated many times, but our domestic bayonet tube joint always stays at a certain standard, far behind the development level of foreign bayonet tube joint.
2. There are still defects in terms of domestic standards
Although the standard of the sleeve pipe connector in China is relatively old and backward, but compared with the domestic standard, there are still problems below the standard, there are shortcomings, such as incomplete connector series, lower pressure level, can not cope with a variety of complex high-pressure occasions。
3. Lack of international diameter changing joint
At present, there is no international tapered joint in the domestic bayon-sleeve pipe joint. Although there are tapered joints with standard diameters, there are some problems in the materials, heat treatment and other aspects of such joints, which lead to the structure not being able to withstand high pressure. For the same reason, type B gusset hose couplings (used in conjunction with bayonet couplings) cannot be used in filling stations.
4. A high proportion of unqualified products
In the international standard, there are high requirements for the manufacturing accuracy, heat treatment hardness of cutting edge, hardness and roundness of steel pipe。 Coupled with the lack of experience and other reasons of the domestic manufacturers of bayonet type pipe joints, leading to a high proportion of unqualified products, making the bayonet type pipe joints in the use of the process of leakage, pulling and other conditions。
5. The assembly quality of bayonet pipe joint is unstable
The assembly process of bayonet tube joint is complicated, which requires the high level and experience of the assembler, especially the pre-installation of bayonet tube joint. At present, there are few professional preassembly machines in China, and most of them rely on manual preassembly of bayonet pipe joints, which is of low working efficiency, and the assembly quality is affected by workers' technical level and professional quality, so the assembly quality is not stable.