Germany is the first country in the world to introduce high-strength fasteners. Since 1953, the Karlsruhe Institute of the Institute has led a special study on high-strength fasteners, and in 1956 completed the interim regulations for the calculation, construction and assembly of high-strength bolted joints. High-strength fasteners of the German DIN standard for decades have not only been widely used in Germany (currently Germany uses 50% of high-strength fasteners) and are recognized in Europe and around the world. There are many similarities between this standard and the US standard; for example, the bolts are divided into 80kg class and 100kg class: the pre-tensioning force of the bolt is not like that of the United States, and it is considered that it is not necessary to exceed the yield point, but the axial force and the shear force are controlled. It can be within 90% of the yield limit. At the same time, special design standards have been developed that are not restricted by past rivet connections. In 1963, the above standards were revised, and then the bolt fastening force, the effective section calculation method, and the fastener standard were further improved and revised. However, Germany still pursues the global standard and its long-term interests, and is still committed to the DIN standard to close to international standards and vigorously implement the ISO standard. It is also because of Germany's strong industrial and technological strengths that its high-strength fasteners have always been among the best in the world in terms of variety and quality. The combination of anti-corrosion and anti-rust technology TMS (special rust) series introduced by Germany in recent years and the combination of “ATVTOP†coatings have improved the corrosion resistance of high-strength fasteners to 11-15 years. And the coating process achieves a high standard of zero pollution and no pollution! This further expands the range of applications for high-strength fasteners. In addition, Germany's increasingly sophisticated R&D-production-distribution (procurement)-service system further enhances the competitiveness of German fastener products (especially high-strength products). For example, the NORMA.GROUP Group, the world's largest designer and manufacturer of pipe fittings and fasteners, is the world's largest supplier of automotive companies (the world's largest in the world). It is reported that the company has In 2005, he entered China to form Norma (China) Co., Ltd., and his eyes fixed on the demand for high-strength fasteners and other products in China's huge automobile market. The operation of this one-stop multinational group will inevitably have a huge impact on the parts manufacturing enterprises. Some people of insight in the world say: "In the near future, it is not the automakers that dominate the parts factories, but zero. The component factory dominates the development of the automotive industry." Refrigerant R1270 Gas,R1270 Replace R502,R1270 Cool Gas Beijing Starget Chemicals Co., Ltd. , http://www.bjrefrigerant.com