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General knowledge of pipe and pipe fittings

Apr 20, 2018

I. pipeline system overview:

In order to deliver liquid or gas, it is necessary to use a variety of pipes. In addition to pipes with straight pipes, the pipes must be used for various pipe fittings.

When the fork is divided, three or four are used, and the flange is used when the joint is connected to the joint. For the purpose of opening the medium, various valves are also used, for heat expansion, cold contraction, or frequent vibration to the pipe system.

The expansion joint is also called the compensator (various forms). In addition, there are various joints connected with all kinds of instruments and meters in the pipeline. The flow medium in the pipeline is different, the corresponding pipe or pipe

It is also necessary to make changes that conform to the technical requirements to ensure the stability and normal adaptability of the pipeline. We are accustomed to the piping system in addition to straight pipe accident other accessories collectively referred to as pipe fittings.

Two. Metal material common sense

Metal materials are the most widely used materials in our daily life and industry. It is mainly divided into steel, iron, alloy and nonferrous metals, and steel is the most widely used material. In steel

The main component is iron, and the rest is the alloy element and the impurity produced during the production. It is because of the different kinds of alloying elements added that different quantities can form a class.

Steel of different materials and different uses. For example, ordinary carbon steel, stainless steel, alloy steel and so on, in these added elements, carbon often plays a very important role.

Common chemical elements in 2.1 steel

A relatively large percentage of iron and steel (Fe) are commonly found in various steels. Besides these, they usually contain several common elements and are also alloying elements in steel.

C (carbon) Si (silicon) Mn (manganese) P (phosphorus) S (sulfur) Cr (chromium) Ni (nickel) Mo (MO) Ti (TI) V (vanadium) and other common elements.

Under normal circumstances, P and S are phosphorus and sulphur as impurities in the production process. The lower the content, the higher the quality of steel.

The division of 2.2 steel:

According to the amount and amount of alloying elements added in the steel, we can simply divide the steel into several categories: carbon steel, stainless steel and alloy steel.

(1) carbon steel: the alloy element is only CSiMnPS five, and then it can be divided into common carbon steel according to the different content of PHP (its requirement is not more than zero point zero four percent) of high carbon steel (its requirement is not more than zero point zero four percent).

Phosphorus content does not exceed its own zero point zero three percent) two common types of carbon steel: Universal carbon steel (Q215A.Q235BF) excellent carbon steel (20. 45. 16MN) and so on.

The strength and toughness of the steel are generally not corrosion-resistant, but because of its low cost, the steel has the highest utilization rate.

(2) alloy steel: in addition to carbon steel containing 5 elements in vitro, the addition of more than ten percent CrMoV and other elements, the common alloy steel is 15CrMo12Cr1MoV1Cr5Mo and so on. Compared with carbon steel,

The strength of the alloy steel is higher, and the heat resistance of the alloy is also improved, but its corrosion resistance is poor. Therefore, the alloy steel is usually used in high temperature and high pressure occasions, such as steel for boiler, which has low corrosion degree.

Power plant thermal steam transportation and so on, the use cost is at medium level.

(3) stainless steel: usually on the basis of carbon steel, a higher proportion of Cr.Ni and other alloys is added, and the content can reach more than twenty percent. Common stainless steel species are: 304304L321316

316L1Cr18Ni9Ti and so on. The first few steel numbers are represented by Japanese and American steel numbers. The last one (1Cr18Ni9Ti) represents the domestic steel numbers. The digital representation of steel

For example, to illustrate the relationship between several stainless steel ingredients: as a general understanding and to facilitate the memory of a beginner, we can think of it (but not very accurate).

Thirty four basic types of steel, only (C less than zero point zero eight percent), Cr (less than eighteen percent), Ni (less than nine percent)

304L ultra low carbon C 304 (C content less than zero point zero five percent) is also called 304L

321304Ti (the content of not more than zero point five percent)

316304Mo (the content of not more than two point five percent)

316L ultra low carbon C 316 (the carbon content of not more than zero point zero five percent) is also called 316L

The strength and toughness index of stainless steel is the best of all kinds of steel. The most special kind of stainless steel is a point of gray corrosion resistance. It is necessary to use stainless steel to achieve its technical re demand in the chemical paper and paper, and so on.