Brief introduction of several common standards for high temperature and high pressure fasteners

Generally, we analyze bolt fracture from the following four aspects: First, the quality of bolts Second, the pre tightening torque of bolts Third, the strength of the bolt Fourth, the fatigue strength of bolts

Fastener is a kind of mechanical part which is widely used for fastening connection. It is widely used in various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemicals, instruments and supplies. It is the most widely used mechanical foundation. It is characterized by a wide variety of specifications, different performance uses, and standardization, seriation, generalization of the degree is also very high. Therefore, some people also call a kind of fastener with existing national standards as standard fastener, or referred to as standard fastener for short.

The steel structure enclosure system includes roofing system, wall system, lighting belt, edging and flooding, gutter and thermal insulation cotton. The enclosure system is one of the most important components of the light steel structure, which determines the ornamental appearance of the building, the waterproof and thermal insulation effect of the building. As an auxiliary fastener, self-drilling self-tapping screws play a vital role in the performance, quality and life of the overall building. It is not optimistic that as such an important basic component, our attention and research are far behind the attention and research on the main components of the building. The most prominent point is the neglect of the performance of fasteners and the main components of the building envelope system. match.

As a key functional part, high-strength fasteners play an important role in the function realization and safe operation of mechanical products. The correct use of high-strength fasteners is a link that cannot be ignored in the design and manufacture of mechanical products. At present, there is no unified method for the use of high-strength fasteners, and the practices of different industries and units are different. Therefore, it is necessary to communicate with each other and develop a scientific method of use to guide the design, manufacture, assembly and maintenance of products. Ensure the safe and stable operation of machinery. After researching and testing high-strength fasteners, this article summarizes the general use methods of high-strength fasteners from the aspects of characteristics, application, selection and assembly. Fasteners have a wide variety of specifications, large usage, and a wide range of applications. They are the most common type of standard parts in mechanical products. The reasonable selection of fasteners has also become an important part of the product design process. The correct use of the product directly affects the product's functional realization and safe operation. Compared with general fasteners, the use requirements of high-strength fasteners in product design, manufacturing, assembly, inspection and maintenance are very different. They also play a more critical role in the operation of equipment. Under the situation of diversified development such as large-scale, automation, and intelligence, high-strength fasteners are increasingly used as key functional parts, especially in critical occasions and important parts. At present, in the selection and use of high-strength fasteners, there are still various opinions and insufficient understanding, and it is necessary to do further research. This article mainly discusses the use of high-strength fasteners for mechanical products, and will not discuss the use of high-strength fasteners to replace general fasteners.

One of the fastening challenges that the rail transit industry needs to address is how to avoid bolt loosening due to dynamic vibration. In the connection of threaded fasteners, various types of alternating loads may be received under actual application conditions, and the partial failure of the threaded connection is usually caused by its own looseness and fatigue damage. Therefore, how to choose suitable anti-loosening products and rigorous anti-loosening designs for customers in the rail transit industry is one of the important tasks in the design of screwed fastening connections.

Stainless steel is a type of steel. Steel refers to those containing less than 2% carbon (C), which is called steel, and more than 2% is iron. Adding chromium (Cr), nickel (Ni), manganese (Mn), silicon (Si), titanium (Ti), molybdenum (Mo) and other alloy elements during the smelting process of the steel improves the performance of the steel and makes the steel corrosion resistant (Ie no rust) is what we often say about stainless steel.

alloy steel In addition to iron and carbon, other alloy elements are added to the steel, which is called alloy steel. An iron-carbon alloy formed by adding an appropriate amount of one or more alloying elements to an ordinary carbon steel. According to the different added elements, and adopt appropriate processing technology, can obtain high strength, high toughness, wear resistance, corrosion resistance, low temperature resistance, high temperature resistance, non-magnetic and other special properties.